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Welcome to the Delaware Risk Assessment Calculator (DERAC). The DERAC is based on the Risk Assessment Information (RAIS)
The purpose of this calculator is to assist risk assessors involved in Department of Natural Resources and Environmental Control (DNREC) projects in decision-making at hazardous waste sites and to determine whether levels of contamination found at the site may warrant further investigation or site cleanup, or whether no further investigation or action may be required.
The risk values presented on this site are chemical-specific values for individual contaminants in air, water, soil and biota that may warrant further investigation or site cleanup.
It should be noted that the risks in this calculator are based upon human health risk and do not address potential ecological risk. Some sites in sensitive ecological settings may also need to be evaluated for potential ecological risk. EPA's guidance "Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessment" contains an eight step process for using benchmarks for ecological effects in the remedy selection process. Additionaly, the Delaware Hazardous Substance Cleanup Act (HSCA) provides ecological risk assessment guidance in its document, "Guidance for Ecological Risk Assessments under HSCA". Ecological Screening Benchmarks can be found in the RAIS Ecological Benchmark Tool.
The excess lifetime cancer risk (ELCR) and hazard quotient (HQ) equations require many chemical-specific parameters including toxicity values and chemical properties. This section describes the calculations and the sources of the chemical-specific inputs.
2.1 Calculating ELCR and HQ
This portion of the risk assessment process is generally referred to as "Risk Characterization". This step incorporates the outcome of the previous activities and calculates the risk or hazard resulting from potential exposure to chemicals via the pathways and routes of exposure determined appropriate for the source area.
The basic equations for calculating excess lifetime carcinogenic risk are:
Oral Risk = DI × SF
or,
Inhalation Risk = DI × IUR
or,
Dermal Risk = DI × (SF/GIABS)
where:
Risk = a unitless probability of an individual developing carcinogenic over a lifetime.
DI = daily intake (mg/kg-day) or µg/m3. DI can be either chronic (CDI) or subchronic (SDI).
SF = slope factor, expressed in (mg/kg-day)-1.
IUR = inhalation unit risk factor, expressed in (µg/m3)-1.
GIABS = Gastro-Intestinal Absorption Factor; which is chemical specific and unitlessThe basic equations for calculating systemic toxicity (i.e., non-carcinogenic hazard) are:
Oral HQ = DI/RfD
or,
Inhalation HQ = DI/RfC
or,
Dermal HQ = DI/(RfD × GIABS)
where:
HQ = Hazard Quotient or The ratio of exposure to the estimated daily exposure level at which no adverse health effects are likely to occur.
DI = daily intake for the toxicant, expressed in [mg/kg-day] or [mg/m3]. DI can be either chronic (CDI) or subchronic (SDI).
RfD = oral reference dose for the toxicant, expressed in mg/kg-day.
RfC = inhalation reference concentration for the toxicant, expressed in mg/m3.
GIABS = Gastro-Intestinal Absorption Factor; which is chemical specific and unitlessThe risk results are color coded to identify risk ranges and potential contaminants of concern. The colors and the associated risk ranges are presented in the tables below.
Hazard Index or Quotient Hazard Range HQ or HI < 0.1 HQ or HI > 0.1 HQ or HI > 1 Color Code No shading Purple Blue
Excess Lifetime Cancer Risk Risk Range Risk < 0.000001 Risk > 0.000001 Risk > 0.0001 Risk > 0.01 Color Code No shading Yellow Red Black 2.2 One-hit Rule Equation
The linear risk equations, listed in section 2.1 General Considerations, are valid only at low risk levels (below estimated risks of 0.01). For sites where chemical intakes might be high (estimated risks above 0.01, an alternate calculation should be used. The one-hit equation, which is consistent with the linear low-dose model, should be used instead (RAGS, part A, ch. 8). The results presented on the DERAC use this rule. In the following instances, one-hit rule is used independently in our risk output tables:
- Risk from a single exposure route for a single chemical.
- Summation of single chemical risk (without one-hit rule applied to single chemical results) for multiple exposure routes (right of each row).
- Summation of risk (without one-hit rule applied to single chemical results) from a single exposure route for multiple chemicals (bottom of each column).
- Summation of total risk (without one-hit rule applied to single chemical results or summations listed above) from multiple chemicals across multiple exposure routes (bottom right hand cell).
2.3 Exposure Assumptions
Risks are based on default exposure parameters and factors that represent Reasonable Maximum Exposure (RME) conditions for long-term/chronic exposures and are based on the methods outlined in EPA’s Risk Assessment Guidance for Superfund, Part B Manual (1991) and Soil Screening Guidance documents (1996 and 2002).
Site-specific information may warrant modifying the default parameters in the equations and calculating site-specific risks. In completing such calculations, the user should answer some fundamental questions about the site. For example, information is needed on the contaminants detected at the site, the land use, impacted media and the likely pathways for human exposure.
Whether these generic risks or site-specific risks are used, it is important to clearly demonstrate the equations and exposure parameters used in deriving risks at a site. A discussion of the assumptions used in the risk calculations should be included in the decision document for the site.
2.4 Toxicity Values
In 2003, EPA's Superfund program revised its hierarchy of human health toxicity values, providing three tiers of toxicity values in a memo (pdf). Three tier 3 sources were identified in that guidance, but it was acknowledged that additional tier 3 sources may exist. The 2003 guidance did not attempt to rank or put the identified tier 3 sources into a hierarchy of their own. However, when developing the PRG and risk calculators, DNREC needed to establish a hierarchy among the tier 3 sources. The toxicity values used as “defaults” in the DERAC are consistent with the 2003 guidance. Chronic and subchronic toxicity values from the following sources, in the order in which they are presented below, are used as the defaults in the DERAC calculator.
- EPA's Integrated Risk Information System (IRIS).
- The Provisional Peer Reviewed Toxicity Values (PPRTVs) derived by EPA's Superfund Health Risk Technical Support Center (STSC) for the EPA Superfund program. PPRTVs are archived (removed) when an IRIS profile is released, even if the IRIS profile indicates a toxicity value could not be derived. PPRTVs will retain subchronic values if IRIS releases a profile without subchronic values.
- EPA's Office of Pesticide Programs (OPP) Human Health Benchmarks for Pesticides (HHBPs). In 2016 IRIS archived 51 chemical assessments for pesticides. For these 51 pesticides IRIS has instead recommended the use of the toxicity values presented in the HHBP table. These include RfDs (also referred to as chronic PADs) and OSFs (referred to as cancer quantification values). In 2016, OPP listed 363 pesticides in the HHBP table. Only the 51 archived by IRIS are used in the RSL calculations.
- The Agency for Toxic Substances and Disease Registry (ATSDR) minimal risk levels (MRLs). An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse non-cancer health effects over a specified duration of exposure. These substance specific estimates, which are intended to serve as screening levels, are used by ATSDR health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites.
- The California Environmental Protection Agency Office of Environmental Health Hazard Assessment (OEHHA) provides toxicity values for the State of California. The OEHHA Toxicity Criteria Database website should be monitored for any updates to the toxicity values.
In the Fall 2009, this new source of toxicity values used was added: screening toxicity values in an appendix to certain PPRTV assessments. While we have less confidence in a screening toxicity value than in a PPRTV, we put these ahead of HEAST toxicity values because these appendix screening toxicity values are more recent and use current EPA methodologies in the derivation, and because the PPRTV appendix screening toxicity values also receive external peer review. To alert users when these values are used, the key presents an "X" (for Appendix) rather than a "P" (for PPRTV). The following is taken from a PPRTV appendix and states the intended usage of appendix screening levels.
"However, information is available for this chemical, which although insufficient to support derivation of a provisional toxicity value, under current guidelines, may be of limited use to risk assessors. In such cases, the Superfund Health Risk Technical Support Center summarizes available information in an appendix and develops a "screening value." Appendices receive the same level of internal and external scientific peer review as the PPRTV documents to ensure their appropriateness within the limitations detailed in the document. Users of screening toxicity values in an appendix to a PPRTV assessment should understand that there is considerably more uncertainty associated with the derivation of an appendix screening toxicity value than for a value presented in the body of the assessment. Questions or concerns about the appropriate use of screening values should be directed to the Superfund Health Risk Technical Support Center."
- The EPA Superfund program's Health Effects Assessment Summary Table. Values in HEAST are archived (removed) when an IRIS profile or a PPRTV paper is released, even if the PPRTV paper indicates a toxicity value could not be derived.
The Agency for Toxic Substances and Disease Registry (ATSDR) minimal risk levels (Draft MRLs).
Values are withdrawn from IRIS or archived from PPRTV or HEAST. The archived values are no longer present on the EPA source websites.
When using toxicity values other than tier 1, users are encouraged to carefully review the basis for the value, and to document its use in decision documentation on a site.
Please contact a DNREC risk assessor for help with chemicals that lack toxicity values in the sources outlined above.
2.4.1 Reference Doses
The current, or recently completed, EPA toxicity assessments used in the DERAC (IRIS and PPRTVs) define a reference dose, or RfD, as an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark dose, or using categorical regression, with uncertainty factors generally applied to reflect limitations of the data used. RfDs are generally the toxicity value used most often in evaluating Noncarcinogenic health effects at Superfund sites. Various types of RfDs are available depending on the exposure route (oral or inhalation), the critical effect (developmental or other), and the length of exposure being evaluated (chronic or subchronic). Some of the risks in this calculator also use Agency for Toxic Substances and Disease Registry (ATSDR) chronic oral minimal risk levels (MRLs) as oral chronic RfDs. Screening toxicity values in an appendix to certain PPRTV assessments were added to the hierarchy in the fall of 2009. The HEAST RfDs used in these risks were based upon then current EPA toxicity methodologies, but did not use the more recent benchmark dose or categorical regression methodologies.
2.4.1.1 Chronic Oral Reference Doses
Chronic oral RfDs are specifically developed to be protective for long-term exposure to a compound. As a guideline for Superfund program risk assessments, chronic oral RfDs generally should be used to evaluate the potential non-carcinogenic effects associated with exposure periods greater than 7 years (approximately 10 percent of a human lifetime). However, this is not a bright line. Note, that ATSDR defines chronic exposure as greater than 1 year for use of their values. The calculator requires the user to select between chronic and subchronic toxicity values.
2.4.1.2 Subchronic Oral Reference Doses
Subchronic oral RfDs are specifically developed to be protective for short-term exposure to a compound. As a guideline for Superfund program risk assessments, subchronic oral RfDs should generally be used to evaluate the potential non-carcinogenic effects of exposure periods between two weeks and seven years. However, this is not a bright line. Note, that ATSDR defines subchronic exposure as less than 1 year for use of their values. The calculator requires the user to select between chronic and subchronic toxicity values.
2.4.2 Reference Concentrations
The current, or recently completed, EPA toxicity assessments used in the DERAC (IRIS and PPRTV assessments) define a reference concentration (RfC) as an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark concentration, or using categorical regression with uncertainty factors generally applied to reflect limitations of the data used. Various types of RfCs are available depending on the exposure route (oral or inhalation), the critical effect (developmental or other), and the length of exposure being evaluated (chronic or subchronic). These also use ATSDR chronic inhalation MRLs as chronic RfCs, intermediate inhalation MRLs as subchronic RfCs and California Environmental Protection Agency (chronic) Reference Exposure Levels (RELs) as chronic RfCs. These may also use some RfCs from EPA's HEAST tables.
2.4.2.1 Chronic Inhalation Reference Concentrations
The chronic inhalation reference concentration is generally used for continuous or near continuous inhalation exposures that occur for 7 years or more. However, this is not a bright line, and ATSDR chronic MRLs are based on exposures longer than 1 year. EPA chronic inhalation reference concentrations are expressed in units of (mg/m3). Cal EPA RELs are presented in ug/m3 and have been converted to mg/m3. Some ATSDR inhalation MRLs are derived in parts per million (ppm) and some in mg/m3. The calculator requires the user to select between chronic and subchronic toxicity values.
2.4.2.2 Subchronic Inhalation Reference Concentrations
The subchronic inhalation reference concentration is generally used for exposures that are between 2 weeks and 7 years. However, this is not a bright line, and ATSDR subchronic MRLs are based on exposures less than 1 year. EPA subchronic inhalation reference concentrations are expressed in units of (mg/m3). Cal EPA RELs are presented in ug/m3 and have been converted to mg/m3. Some ATSDR intermediate inhalation MRLs are derived in parts per million (ppm) and some in mg/m3. The calculator requires the user to select between chronic and subchronic toxicity values.
2.4.3 Slope Factors
A slope factor and the accompanying weight-of-evidence determination are the toxicity data most commonly used to evaluate potential human carcinogenic risks. Generally, the slope factor is a plausible upper-bound estimate of the probability of a response per unit intake of a chemical over a lifetime. The slope factor is used in risk assessments to estimate an upper-bound lifetime probability of an individual developing carcinogenic as a result of exposure to a particular level of a potential carcinogen. Slope factors should always be accompanied by the weight-of-evidence classification to indicate the strength of the evidence that the agent is a human carcinogen.
Oral slope factors are toxicity values for evaluating the probability of an individual developing carcinogenic from oral exposure to contaminant levels over a lifetime. Oral slope factors are expressed in units of (mg/kg-day)-1. When available, oral slope factors from EPA's IRIS or PPRTV assessments are used. The ATSDR does not derive carcinogenic toxicity values (e.g. slope factors or inhalation unit risks). Some oral slope factors used in the DERAC were derived by the California Environmental Protection Agency, whose methodologies are quite similar to those used by EPA's IRIS and PPRTV assessments. Screening toxicity values in an appendix to certain PPRTV assessments were added to the hierarchy in the fall of 2009. When oral slope factors are not available in IRIS then PPRTVs, Cal EPA assessments, PPRTV appendices or values from HEAST are used.
2.4.4 Inhalation Unit Risk
The IUR is defined as the upper-bound excess lifetime carcinogenic risk estimated to result from continuous exposure to an agent at a concentration of 1 µg/m3 in air. Inhalation unit risk toxicity values are expressed in units of (µg/m3)-1.
When available, inhalation unit risk values from EPA's IRIS or PPRTV assessments are used. The ATSDR does not derive carcinogenic toxicity values (e.g. slope factors or inhalation unit risks). Some inhalation unit risk values used in the DERAC were derived by the California Environmental Protection Agency, whose methodologies are quite similar to those used by EPA's IRIS and PPRTV assessments. Screening toxicity values in an appendix to certain PPRTV assessments were added to the hierarchy in the fall of 2009. When inhalation unit risk values are not available in IRIS then PPRTVs, Cal EPA assessments, PPRTV appendices or values from HEAST are used.
2.4.5 Toxicity Equivalence Factors
Some chemicals are members of the same family and exhibit similar toxicological properties; however, they differ in the degree of toxicity. Therefore, a toxicity equivalence factor (TEF) must first be applied to adjust the measured concentrations to a toxicity equivalent concentration.
The following table contains the various dioxin-like toxicity equivalency factors for Dioxins, Furans and dioxin-like PCBs (Van den Berg et al. 2006), which are the World Health Organization 2005 values. These TEFs are also presented in the May 2013 fact sheet, Use of Dioxin TEFs in Calculating Dioxin TEQs at CERCLA and RCRA Sites which references the 2010 EPA report, Recommended Toxicity Equivalence Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8Tetrachlorodibenzo-p-dioxin and Dioxin-Like Compounds
Dioxin Toxicity Equivalence Factors
Chlorinated dibenzo-p-dioxins
TEF
1 1 0.1 0.1 0.1 0.01 0.0003 Chlorinated dibenzofurans
TEF
0.1 0.03 0.3 0.1 0.1 0.1 0.1 0.01 0.01 0.0003 PCBs
TEF
IUPAC No. Structure Non-ortho 77 3,3',4,4'-TetraCB 0.0001 81 3,4,4',5-TetraCB 0.0003 126 3,3',4,4',5-PeCB 0.1 169 3,3',4,4',5,5'-HxCB 0.03 Mono-ortho 105 2,3,3',4,4'-PeCB 0.00003 114 2,3,4,4',5-PeCB 0.00003 118 2,3',4,4',5-PeCB 0.00003 123 2',3,4,4',5-PeCB 0.00003 156 2,3,3',4,4',5-HxCB 0.00003 157 2,3,3',4,4',5'-HxCB 0.00003 167 2,3',4,4',5,5'-HxCB 0.00003 189 2,3,3',4,4',5,5'-HpCB 0.00003 Di-ortho* 170 2,2',3,3',4,4',5-HpCB 0.0001 180 2,2',3,4,4',5,5'-HpCB 0.00001 * Di-ortho values come from Ahlborg, U.G., et al. (1994), which are the WHO 1994 values from Toxic equivalency factors for dioxin-like PCBs: Report on WHO-ECEH and IPCS consultation, December 1993 Chemosphere, Volume 28, Issue 6, March 1994, Pages 1049-1067.
2.4.6 Relative Potency Factors (RPFs)
Some chemicals are members of the same family and exhibit similar toxicological properties; however, they differ in the degree of toxicity. Therefore, a relative potency factor (RPF) must first be applied to adjust the oral slope factor or inhalation unit risk based on the realtive potency to the primary compound.
Carcinogenic polycyclic aromatic hydrocarbons
Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons (EPA/600/R-93/089, July 1993), recommends that a RPF be used to convert concentrations of carcinogenic polycyclic aromatic hydrocarbons (cPAHs) to an equivalent concentration of benzo(a)pyrene when assessing the cancer risks posed by these substances from oral exposures. These RPFs are based on the potency of each compound relative to that of benzo(a)pyrene. For the toxicity value database, these RPFs have been applied to the toxicity values. Although this is not in complete agreement with the direction in the aforementioned documents, this approach was used so that toxicity values could be generated for each cPAH. Additionally, it should be noted that computationally it makes little difference whether the RPFs are applied to the concentrations of cPAHs found in environmental samples or to the toxicity values as long as the RPFs are not applied to both. However, if the adjusted toxicity values are used, the user will need to sum the risks from all cPAHs as part of the risk assessment to derive a total risk from all cPAHs. A total risk from all cPAHs is what is derived when the RPFs are applied to the environmental concentrations of cPAHs and not to the toxicity values. These RPFs are not needed, and should not be used, with the Cal EPA toxicity values, nor should they be used when calculating non-cancer risk. See FAQ no. 42.
The IRIS Profile gives the following instructions for RPF application:
"It (BaP) also serves as an index chemical for deriving relative potency factors to estimate the carcinogenicity of other PAH congeners, such as in EPA's Relative Potency Factor approach for the assessment of the carcinogenicity of PAHs (U.S. EPA, 1993)."
and
"The inhalation unit risk for benzo[a]pyrene is derived with the intention that it will be paired with EPA's relative potency factors for the assessment of the carcinogenicity of PAH mixtures. In addition, regarding the assessment of early life exposures, because cancer risk values calculated for benzo[a]pyrene were derived from adult animal exposures, and because benzo[a]pyrene carcinogenicity occurs via a mutagenic mode of action, exposures that occur during development should include the application of ADAFs (see Section 2.5)."
The following table presents the RPFs for cPAHs recommended in Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons.
Relative Potency Factors for Carcinogenic Polycyclic Aromatic Hydrocarbons
Compound RPF Benzo(a)pyrene 1.0 Benz(a)anthracene 0.1 Benzo(b)fluoranthene 0.1 Benzo(k)fluoranthene 0.01 Chrysene 0.001 Dibenz(a,h)anthracene 1.0 Indeno(1,2,3-c,d)pyrene 0.1 2.5 Chemical-specific Parameters
Several chemical-specific parameters are needed to calculate DI. The hierarchies are generally applicable for organic and inorganic compounds.
2.5.1 Sources
Many sources are used to populate the database of chemical-specific parameters. Major sources are curated as individual data tables and designated by the name of the source (i.e.; PHYSPROP, EPI, CRC, etc.). Minor sources are curated together in an individual data table designated as "Other". The sources are briefly described below.
The major sources are:
The Physical Properties Database (PHYSPROPExit) was developed by Syracuse Research Corporation (SRC). The PhysProp database contains chemical structures, names and physical properties for over 41,000 chemicals. Physical properties collected from a wide variety of sources include experimental, extrapolated and estimated values.
The Estimation Programs Interface (EPI SuiteTM) was developed by the US Environmental Protection Agency's Office of Pollution Prevention and Toxics and SRC. These programs estimate various chemical-specific properties. The calculations for these SL tables use the experimental values for a property over the estimated values.
CRC Handbook of Chemistry and PhysicsExit. (Various Editions)
Perry's Chemical Engineers' Handbook (Various Editions).McGraw-Hill. Online version available hereExit. Green, Don W.; Perry, Robert H. (2008).
Lange's Handbook of Chemistry (Various Editions). Online version available hereExit. Speight, James G. (2005). McGraw-Hill.
Yaws' Handbook of Thermodynamic and Physical Properties of Chemical Compounds. Knovel, 2003.
EPA Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites (SSL) and Appendix A-C (39 pp, 681 K), "Chemical Properties and Regulatory/Human Health Benchmarks for SSL Calculations". Table C-1: Chemical-Specific Properties used in SSL Calculations and Table C-4: Metal Kd Values (L/kg) as a Function of pH.
Summary of Physical/Chemical and Environmental Parameters for PFAS : Subject to Interim Special Order by Consent No. 20-086-CWP/AP/GW/HW/DW/SW, paragraph 37(J)(3). Environmental Studies Report E21-0037. 3M, 2021
Baes, C.F. 1984. Oak Ridge National Laboratory. A Review and Analysis of Parameters for Assessing Transport of Environmentally Released Radionuclides through Agriculture. Values are also found in Superfund Chemical Data Matrix (SCDM).
U.S. EPA 2004. Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) Final. OSWER 9285.7-02EP. July 2004. Document (PDF) (186 pp, 4.2 MB) and website.
U.S. EPA 2015 Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. OSWER Publication 9200.2-154 and associated calculation spreadsheet (VISL).
Some of the more commonly used minor sources are:
The PubChem website published by the National Center for Biotechnology Information, U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD20894, USA.
The Hazardous Substance Data Bank (HSDB) website published by the U.S. National Library of Medicine 8600 Rockville Pike, Bethesda, MD 20894 National Institutes of Health, Health & Human Services.
CompTox Chemicals Dashboard website published by the US Environmental Protection Agency containing measured and predicted data for 883,000 chemicals.
The Agency for Toxic Substances & Disease Registry (ATSDR) Toxicological Profiles. Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341.
NIOSH Pocket Guide to Chemical Hazards (NPG), NIOSH Publication No. 97-140, February 2004.
WATER9 Version 2.0 is the Windows-based wastewater treatment model containing a database listing many organic compounds and procedures for obtaining reports of constituent fates, including air emissions and treatment effectiveness. This program supersedes WATER8, Chem9, and Chemdat8 WATER9.
CHEMFATE Database. CHEMFATE is part of the Environmental Fate Data Bases (EFDB) software developed by SRC under sponsorship of the U.S. Environmental Protection Agency. CHEMFATE contains physical property values, rate constants, and monitoring data for approximately 1700 chemicals.
The ARS Pesticide Properties Database: U.S. Department of Agriculture, Agricultural Research Service. 2009. Document (PDF) (393 pp, 775 K) and website.
Other sources for esoteric chemicals with sparsely published physicochemical parameters.
2.5.2 Hierarchy by Parameter
The hierarchies below present the major sources in order of selection. Minor sources are interspersed throughout the hierarchies in a collection called "Other". These hierarchies are generally representative of both organic and inorganic compounds. The 3M chemical properties for PFAS is the first source for all parameters for PFAS compounds.
- Organic Carbon Partition Coefficient (Koc) (L/kg). Not applicable for inorganics. Other; EPI estimated values; SSL, Yaws' estimated values; EPI experimental values; Yaws' Experimental values. The exception to this hierarchy are the nine ionizable organics identified in table 42 of Part 5 of the Soil Screening Guidance Technical Background Document (PDF) (28 pp, 523 K). Appendix L goes into detail on the derivation of these values. The table is reproduced below:
Compound Koc
pH=6.8FBenzoic acid 0.6 2-chlorophenol 388 2,4-dichlorophenol 147 2,4-dinitrophenol 0.01 pentachlorophenol (PCP) 592 2,3,4,5-tetrachlorophenol 4742 2,3,4,6-tetrachlorophenol 280 2,4,5-trichlorophenol 1597 2,4,6-trichlorophenol 381
Dermal Permeability Coefficient (Kp) (cm/hour). EPI estimated values; RAGS Part E estimated value.
Effective Predictive Domain (EPD). Calculated based on RAGS Part E criteria for MW and log Kow.
Fraction Absorbed (FA). RAGS Part E Exhibit B-3; Calculated. Calculated FA values less than zero are set to zero.
Molecular Weight (MW) (g/mole). PHYSPROP; EPI; CRC; Perry's; Lange's; Yaws'; Other.
Water Solubility (S) (mg/L at 25 °C, unless otherwise stated in the source). PHYSPROP experimental values; EPI experimental values; CRC; Yaws' experimental values; Perry's; Lange's; PHYSPROP estimated values; Yaws estimated values; EPI estimated values (WATERNT v.1.01, WSKOWWIN v1.42 respectively); Other.
Unitless Henry's Law Constant (H' at 25 °C, unless otherwise stated in the source.). PHYSPROP experimental values; EPI experimental values; Yaws' experimental values; CRC; PHYSPROP extrapolated values; PHYSPROP estimated values; EPI group-estimated values; EPI bond-estimated values; Other.
Henry's Law Constant (atm-m3/mole at 25 °C, unless otherwise stated in the source). PHYSPROP experimental values; EPI experimental values; Yaws' experimental values; CRC; PHYSPROP extrapolated values; PHYSPROP estimated values; EPI group-estimated values; EPI bond-estimated values; Other.
Diffusivity in Air (Dia) (cm2/s). WATER9 equations.
Diffusivity in Water (Diw) (cm2/s). WATER9 equations.
Fish Bioconcentration Factor (BCF) (L/kg). EPI experimental values; EPI estimated values; Other.
Soil-Water Partition Coefficient (Kd) (cm3/g). SSL; BAES; Other.
Density (g/cm3). CRC; Perry's; Lange's; Other.
Melting Point (MP °C). PHYSPROP experimental values; EPI experimental values; CRC; Perry's; Lange's; Yaws' freezing point; EPI estimated values; Other.
log Octanol-Water Partition Coefficient (logKow). PHYSPROP experimental values, EPI experimental values; CRC; Yaws experimental values; PHYSPROP extrapolated; PHYSPROP estimated; EPI estimated values; Yaws estimated values; Other.
Vapor Pressure (VP). PHYSPROP experimental values, EPI experimental values; CRC; PHYSPROP extrapolated values; PHYSPROP estimated values; EPI estimated values; Other.
Critical Temperature (Tc °K). CRC; Yaws' Experimental; Yaws' Estimated; VISL; Other.
Enthalpy of vaporization at the normal boiling point (cal/mol). CRC; VISL; Yaws' extrapolated; Yaws' Estimated.
Lower Explosive Limit (LEL). CRC; Yaws' experimental; Yaws' extrapolated; Yaws' estimated; VISL
Soil to milk transfer factor-wet (Bvwet (kg (soil) / kg (fresh mass)). Bvwet is determined by the following equation 7.9 x 10-9 Kow, taken from McKone (1994).
Soil to milk transfer factor-dry (Bvdry (day (soil) / kg (dry mass)). Bvdry values were derived from Bvwet, assuming that dry mass is 20% of the fresh mass.
Soil to beef transfer factor-wet (Bvwet (kg (soil) / kg (fresh mass)). Bvwet is determined by the following equation 2.5 x 10-9 Kow, taken from McKone (1994).
Soil to beef transfer factor-dry (Bvdry (day (soil) / kg (dry mass)). Bvdry values were derived from Bvwet, assuming that dry mass is 20% of the fresh mass.
Soil to plant transfer factor-wet (Bvwet (kg (soil) / kg (fresh mass)). Bvwet is determined by the following equation 7.7 x Kow-0.58, taken from McKone (1994).
Soil to plant transfer factor-dry (Bvdry (kg (soil) / kg (dry mass)). Bvdry values were derived from Bvwet, assuming that dry mass is 20% of the fresh mass.
2.6 Maximum Contaminant Levels (MCLs)
The Safe Drinking Water Act (SDWA) was originally passed by Congress in 1974 to protect public health by regulating the nation's public drinking water supply. SDWA authorizes the United States Environmental Protection Agency (US EPA) to set national health based standards for drinking water to protect against both naturally-occurring and man-made contaminants that may be found in drinking water.
US EPA sets national standards for drinking water based on sound science to protect against health risks, considering available technology and costs. These National Primary Drinking Water Regulations set enforceable maximum contaminant levels (MCLs) for particular contaminants in drinking water or required ways to treat water to remove contaminants. The MCLs are published here.
US EPA sets primary drinking water standards through a three-step process: First, US EPA identifies contaminants that may adversely af fect public health and occur in drinking water with a frequency and at levels that pose a threat to public health. Second, US EPA determines a maximum contaminant level goal (MCLG) for contaminants it decides to regulate. This goal is the level of a contaminant in drinking water below which there is no known or expected risk to health. Third, US EPA specifies a MCL, the maximum permissible level of a contaminant in drinking water which is delivered to any user of a public water system. These levels are enforceable standards, and are set as close to the goals as feasible.
The State of Delaware provides MCLs in its administrative code, "Title 16 - Department of Health and Social Services - Division of Public Health - Health Systems Protection (HSP)", regulation.
2.7 EPA Office of Water (OW) Health Advisories (HAs)
The Health Advisories Program, sponsored by the EPA OW, publishes concentrations of drinking water contaminants at drinking water specific risk level concentration for cancer (10-4 cancer Risk) and concentrations of drinking water contaminants at which noncancer adverse health effects are not anticipated to occur over specific exposure durations - one-day, ten-day, and Lifetime. The one-day and ten-day HAs are for a 10 kg child and the Lifetime HA is for a 70 kg adult. The daily drinking water consumption for the 10 kg child and 70 kg adult are assumed to be 1 L/day and 2 L/day, respectively. The Lifetime HA for the drinking water contaminant is calculated from its associated drinking water equivalent level (DWEL), obtained from its RfD, and incorporates a drinking water Relative Source Contribution (RSC) factor of contaminant-specific data or a default of 20% of total exposure from all sources. MCLs and MCLGs for some regulated drinking water contaminants are also published.
HAs serve as the informal technical guidance for unregulated drinking water contaminants to assist Federal, State and local officials, and managers of public or community water systems in protecting public health as needed. They are not to be construed as legally enforceable Federal standards. EPA's OW has provided MCL, MCLGs, RfDs, One-Day HAs, Ten-day HAs, DWELs, and Lifetime HAs. Drinking Water Specific Risk Level Concentration for cancer (10-4 Cancer Risk), and Cancer Descriptors in the DWSHA tables. HAs are intended to protect against noncancer effects. The 10-4 Cancer Risk level provides information concerning cancer effects. The MCL values for specific drinking water contaminants must be used for regulated contaminants in public drinking water systems.
HAs for ten-day and 10-4 cancer risk are provided in the calculator output for ease of performing data screens. The HAs are not calculated with the same water intake rate, body weight, target cancer risk, use of prorating exposure, at times toxicity values, or use of relative source contribution as are used.
In default mode the risk DERAC produces generic risk results with site concentrations based on default exposure parameters. In site-specific mode, the DERAC allows for site-specific exposure parameters to be used with site concentrations. These risk results can be used for:
Risks are provided for multiple exposure pathways and for chemicals with both carcinogenic and non-carcinogenic effects. site-specific risks corresponding to an HQ less than 1 and ELCR less than 10-6 are generally acceptable. Caution is recommended to ensure that cumulative carcinogenic risk for all actual and potential carcinogenic contaminants found at the site do not have a residual (after site cleanup, or when it has been determined that no site cleanup is required) carcinogenic risk exceeding 10-5.
3.1 Developing a Conceptual Site Model
The DNREC provides guidance on conducting human health risk assessments in, "Guidance for Human Health Risk Assessments (HHRA) under the Hazardous Substance Cleanup Act (HSCA)". This guidance should be consulted to ensure all procedures required by DNREC are considered.
When calculating risk at a site, the exposure pathways of concern and site conditions should match those used in developing CDIs here. (Note, however, that future uses may not match current uses. Future uses are potential site uses that may occur in the future. Future uses should be considered as well as current uses. RAGS Part A, Chapter 6, provides guidance on selecting future-use receptors.) Thus, it is necessary to develop a conceptual site model (CSM) to identify likely contaminant source areas, exposure pathways, and potential receptors. This information can be used to determine the applicability of risks at the site and the need for additional information. The final CSM diagram represents linkages among contaminant sources, release mechanisms, exposure pathways, and routes and receptors based on historical information. It summarizes the understanding of the contamination problem. A separate CSM for ecological receptors can be useful. Part 2 and Attachment A of the Soil Screening Guidance for Superfund: Users Guide (EPA 1996) contains the steps for developing a CSM.
Below is a CSM of the quantified pathways addressed in the DERAC.
As a final check, the CSM should address the following questions:
- Are there potential ecological concerns?
- Is there potential for land use other than those used in the risk calculations (i.e., residential and commercial/industrial)?
- Are there other likely human exposure pathways that were not considered in development of the risks?
- Are there unusual site conditions (e.g. large areas of contamination, high fugitive dust levels, potential for indoor air contamination)?
The risks may need to be adjusted to reflect the answers to these questions.
3.3 Potential Problems
As with any risk based screening tool, the potential exists for misapplication. In most cases, this results from not understanding the intended use of the risks. In order to prevent misuse of the risks, the following should be avoided:
- Applying risks to a site without adequately developing a conceptual site model that identifies relevant exposure pathways and exposure scenarios.
- Not considering the effects from the presence of multiple contaminants, where appropriate.
- Use of the risks or cleanup levels without adequate consideration of the other NCP remedy selection criteria on CERCLA sites.
- Use of outdated risks (as more recent toxicity values may exist).
- Not considering the effects of additivity when screening multiple chemicals.
- Applying inappropriate target risks or changing a carcinogenic target risk without considering its effect on non-carcinogenic, or vice versa.
- Not performing additional screening for pathways not included in these risks (e.g. vapor intrusion).
The chronic daily intake (CDI) equations consider human exposure to individual contaminants in air, water, soil, sediment and biota. The technical discussion is aimed at producing risk results. The following text presents the land use equations and their exposure routes. Tables 1 through 27 in Section 6 present the definitions of the variables and their default values. Any alternative values or assumptions used in developing risks on a site should be presented with supporting rationale in the decision documents.
The CDI equations have evolved over time and are a combination of the following guidance documents:
4.1 Resident
4.1.1 Resident Soil
This receptor spends most, if not all, of the day at home. The activities for this receptor involve typical home making chores (cooking, cleaning and laundering) as well as outdoor activities. The resident is assumed to be exposed to contaminants via the following pathways: incidental ingestion of soil, dermal contact with soil, inhalation of volatiles and fugitive dust. Adults and children exhibit different ingestion rates for soil. For example, the child resident is assumed to ingest 200 mg per day while the adult ingests 100 mg per day. To account for changes in intake as the receptor ages, age adjusted intake equations were developed.
4.1.1.1 Noncarcinogenic for Child
The residential soil CDI equations, presented here for child exposures, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.2 Noncarcinogenic for Adult
The residential soil CDI equations, presented here for adult exposures, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.3 Noncarcinogenic Age-adjusted
The residential soil CDI equations, presented here for age-adjusted exposures, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.4 Carcinogenic
The residential soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.5 Mutagenic
The residential soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.6 Vinyl Chloride - Carcinogenic
The residential soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.7 Trichloroethylene - Carcinogenic and Mutagenic
The residential soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal contact with soil.
4.1.1.8 Supporting Equations for Resident Soil
Child Supporting Equations.
Adult Supporting Equations.
Age-adjusted Supporting Equations.
4.1.2 Resident Tapwater
This receptor is exposed to chemicals in water that are delivered into a residence from sources such as groundwater or surface water. Ingestion of drinking water is an appropriate pathway for all chemicals. The inhalation exposure route is only calculated for volatile compounds. Activities such as showering, laundering, and dish washing contribute to contaminants in the air for inhalation. Dermal contact with tapwater is also considered for analytes determined to be within the effective predictive domain as described in Section 4.11.8.
4.1.2.1 Noncarcinogenic for Child
The tapwater CDI equations, presented here for child exposures, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.2 Noncarcinogenic for Adult
The tapwater CDI equations, presented here for adult exposures, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.3 Noncarcinogenic for Age-adjusted
The tapwater CDI equations, presented here for age-adjusted exposures, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.4 Carcinogenic
The tapwater CDI equations, presented here, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.5 Mutagenic
The tapwater CDI equations, presented here, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.6 Vinyl Chloride - Carcinogenic
The tapwater CDI equations, presented here, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.7 Trichloroethylene - Carcinogenic and Mutagenic
The tapwater CDI equations, presented here, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.1.2.8 Supporting Equations for Tapwater
Child Supporting Equations.
Adult Supporting Equations.
Age-adjusted Supporting Equations.
4.1.3 Resident Air
This receptor spends most, if not all, of the day at home. The activities for this receptor involve typical home making chores (cooking, cleaning and laundering) as well as outdoor activities. The resident is assumed to be exposed to contaminants via the following pathway: inhalation of ambient air. This land use has no assumptions of how contaminants get into the air.
4.1.3.1 Noncarcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.1.3.2 Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.1.3.3 Mutagenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation
4.1.3.4 Vinyl Chloride - Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.1.3.5 Trichloroethylene - Carcinogenic and Mutagenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.1.4 Consumption of Fish
4.1.4.1 Concentration in Fish
The fish CDI represents the concentration, in the fish, that can be consumed. Note: the consumption rate for fish is not age adjusted for this land use. Also, the SL calculated for fish is not for surface water or soil but is for fish tissue.
4.1.4.1.1 Noncarcinogenic
The ingestion of fish equation, presented here, contains the following exposure route:
consumption of fish.
4.1.4.1.2 Carcinogenic
The ingestion of fish equation, presented here, contains the following exposure route:
consumption of fish.
4.1.4.2 Concentration in Surface Water
This fish CDI represents the concentration, in the surface water that is protective off consumers eating fish. Note: the consumption rate for fish is not age adjusted for this land use.
4.1.4.2.1 Noncarcinogenic
The ingestion of fish equation, presented here, contains the following exposure route:
consumption of fish.
4.1.4.2.2 Carcinogenic
The ingestion of fish equation, presented here, contains the following exposure route:
consumption of fish.
Note: the consumption rate for fish is not age adjusted for this land use.
4.1.5 Soil to Groundwater
The soil to groundwater media uses the same water concentration determination equations for resident and indoor worker based on the respective soil concentration entered by the user for each land use. The graphical representation below illustrates the transport of contaminants from soil to groundwater for the resident land use. For more information about soil to groundwater, including equation images, please see section 4.9 of this user guide.
4.2 Composite Worker
4.2.1 Composite Worker Soil
This is a long-term receptor exposed during the work day who is a full-time employee working on-site and spends most of the workday conducting maintenance activities outdoors. The activities for this receptor (e.g., moderate digging, landscaping) typically involve on-site exposure to surface soils. The composite worker is expected to have an elevated soil ingestion rate (100 mg per day) and is assumed to be exposed to contaminants via the following pathways: incidental ingestion of soil, dermal contact with soil, inhalation of volatiles and fugitive dust. The composite worker combines the most protective exposure assumptions of the outdoor and indoor workers. The only difference between the outdoor worker and the composite worker is that the composite worker uses the more protective exposure frequency of 250 days/year from the indoor worker scenario.
4.2.1.1 Noncarcinogenic
The composite worker soil CDI equations, presented here, combine the most protective exposure parameters from the outdoor and indoor worker. The composite worker contains the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.2.1.2 Carcinogenic
The composite worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.2.2 Composite Worker Air
This is a long-term receptor exposed during the work day who is a full-time employee working on-site and spends most of the workday conducting maintenance activities indoors. The composite worker is assumed to be exposed to contaminants via the following pathway: inhalation of ambient air. The composite worker combines the most protective exposure assumptions of the outdoor and indoor workers. The only difference between the outdoor worker and the composite worker is that the composite worker uses the more protective exposure frequency of 250 days/year from the indoor worker scenario. This land use has no assumptions of how contaminants get into the air.
4.2.2.1 Noncarcinogenic
The composite worker ambient air CDI equation, presented here, combines the most protective parameters from the outdoor and indoor workers. The composite worker contains the following exposure route:
inhalation.
4.2.2.2 Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure routes:
inhalation.
4.3 Outdoor Worker
4.3.1 Outdoor Worker Soil
This is a long-term receptor exposed during the work day who is a full-time employee working on-site and spends most of the workday conducting maintenance activities outdoors. The activities for this receptor (e.g., moderate digging, landscaping) typically involve on-site exposure to surface soils. The outdoor worker is expected to have an elevated soil ingestion rate (100 mg per day) and is assumed to be exposed to contaminants via the following pathways: incidental ingestion of soil, dermal contact with soil, inhalation of volatiles and fugitive dust. The outdoor worker receives more exposure than the indoor worker under commercial/industrial conditions.
4.3.1.1 Noncarcinogenic
The outdoor worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.3.1.2 Carcinogenic
The outdoor worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.3.2 Outdoor Worker Air
This is a long-term receptor exposed during the work day who is a full-time employee working on-site and spends most of the workday conducting maintenance activities outdoors. The outdoor worker is assumed to be exposed to contaminants via the following pathway: inhalation of ambient air. This land use has no assumptions of how contaminants get into the air.
4.3.2.1 Noncarcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.3.2.2 Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.4 Indoor Worker
4.4.1 Indoor Worker Soil
This receptor spends most, if not all, of the workday indoors. Thus, an indoor worker has no direct dermal contact with outdoor soils. This worker may, however, be exposed to contaminants through ingestion of contaminated soils that have been incorporated into indoor dust and inhalation of volatiles and particulates from outside soils. CDIs calculated for this receptor are expected to be protective of both workers engaged in low intensity activities such as office work and those engaged in more strenuous activity (e.g., factory or warehouse workers).
4.4.1.1 Noncarcinogenic
The indoor worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil and
inhalation of particulates emitted from soil.
4.4.1.2 Carcinogenic
The indoor worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil and
inhalation of particulates emitted from soil.
4.4.2 Indoor Worker Air
This is a long-term receptor exposed during the work day who is a full-time employee working on-site and spends most of the workday conducting maintenance activities indoors. The indoor worker is assumed to be exposed to contaminants via the following pathway: inhalation of ambient air. This land use has no assumptions of how contaminants get into the air.
4.4.2.1 Noncarcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.4.2.2 Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure routes:
inhalation.
4.4.3 Indoor Worker Tapwater
This receptor is exposed to chemicals in water that are delivered into a commercial/industrial facility from sources such as groundwater or surface water. Ingestion of drinking water is an appropriate pathway for all chemicals. The inhalation exposure route is only calculated for volatile compounds. Activities such as showering, laundering, and dish washing contribute to contaminants in the air for inhalation. Dermal contact with tapwater is also considered for analytes determined to be within the effective predictive domain as described in Section 4.11.8.
4.4.3.1 Noncarcinogenic
The tapwater CDI equations, presented here, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.4.3.2 Carcinogenic
The tapwater CDI equations, presented here, contain the following exposure routes:
ingestion of water,
dermal contact with water, and
inhalation of volatiles.
4.4.4 Soil to Groundwater
The soil to groundwater media uses the same water concentration determination equations for resident and indoor worker based on the respective soil concentration entered by the user for each land use. The graphical representation below illustrates the transport of contaminants from soil to groundwater for the indoor worker land use. For more information about soil to groundwater, including equation images, please see section 4.9 of this user guide.
4.5 Construction Worker
4.5.1 Construction Worker Soil Exposure to Unpaved Road Traffic
The construction land use is described in the supplemental soil screening guidance. This land use is limited to an exposure duration of 1 year and is thus, subchronic. Other unique aspects of this scenario are that the particulate emission factor (PEF) is based on mechanical disturbance of the soil and a special volatilization factor (VF) equation is used. See Section 4.1.3 for further information on subchronic VFs and PEFs. The PEFs calculated in these scenarios may predict much higher air concentrations than the standard wind-driven PEFs; however, the inhalation screening level will likely be dominated by the VF in the case of a volatile contaminant. VFs are commonly 5 orders of magnitude more protective than PEFs. Additionally, the ingestion route typically is the driving factor in most risk calculations. Two types of mechanical soil disturbance are addressed: standard vehicle traffic and other than standard vehicle traffic (e.g. wind, grading, dozing, tilling and excavating). In general, the intake and contact rates are all greater than the outdoor worker. Exhibit 5-1 in the supplemental soil screening guidance presents the exposure parameters.
4.5.1.1 Noncarcinogenic
The construction worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.5.1.2 Carcinogenic
The construction worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.5.2 Construction Worker Soil Exposure to Other Construction Activities
This is a short-term receptor exposed during the work day working around vehicles suspending dust in the air. The activities for this receptor (e.g., trenching, excavating) typically involve on-site exposure to surface soils. The construction worker is expected to have an elevated soil ingestion rate (330 mg per day) and is assumed to be exposed to contaminants via the following pathways: incidental ingestion of soil, dermal contact with contaminants in soil, inhalation of volatiles and fugitive dust. The only difference between this construction worker and the one described in section 4.5.1 is that this construction worker uses a different PEF. The construction land use is described in the supplemental soil screening guidance. This land use is limited to an exposure duration of 1 year and is thus, subchronic. Other unique aspects of this scenario are that the PEF is based on mechanical disturbance of the soil. Two types of mechanical soil disturbance are addressed: standard vehicle traffic and other than standard vehicle traffic (e.g. wind, grading, dozing, tilling and excavating). In general, the intakes and contact rates are all greater than the outdoor worker. Exhibit 5-1 in the supplemental soil screening guidance presents the exposure parameters.
4.5.2.1 Noncarcinogenic
The construction worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.5.2.2 Carcinogenic
The construction worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.5.3 Construction Worker Air
This is a short-term receptor exposed during the work day during heavy construction activities outdoors. The activities for this receptor (e.g., trenching, excavating) typically involve on-site exposures to surface soils. The construction worker is assumed to be exposed to contaminants via the following pathways: inhalation of ambient air and external radiation from contaminants in ambient air. This land use has no assumptions of how contaminants get into the air.
4.5.3.1 Noncarcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.5.3.2 Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.6 Excavation Worker
4.6.1 Excavation Worker Soil
The excavation worker land use was developed for use at DOE ORO facilities to address short term exposures. Example situations for exposure would be utility line maintenance or installation. This land use is limited to an exposure duration of 1 year and is thus, subchronic. The PEF and VF used in this land use are the same ones used in the resident and composite worker land use scenarios. In general, the intake and contact rates are all greater than the outdoor worker.
4.6.1.1 Noncarcinogenic
The excavation worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.6.1.2 Carcinogenic
The excavation worker soil CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil,
inhalation of particulates emitted from soil, and
dermal exposure.
4.6.2 Excavation Worker Air
The excavation worker land use was developed for use at DOE ORO facilities to address short term exposures. This land use is limited to an exposure duration of 1 year and is thus, subchronic. In general, the intake and contact rates are all greater than the outdoor worker.
4.6.2.1 Noncarcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.6.2.2 Carcinogenic
The Ambient air CDI equation, presented here, contains the following exposure route:
inhalation.
4.7 Recreator
4.7.1 Recreator Soil/Sediment
This receptor spends time outside involved in recreational activities. The recreator is assumed to be exposed to contaminants via the following pathways: incidental ingestion of soil, dermal contact with contaminants in soil, and inhalation of volatiles and fugitive dust.
4.7.1.1 Noncarcinogenic for Child
The recreational soil/sediment CDI equations, presented here for child exposures, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.2 Noncarcinogenic for Adult
The recreational soil/sediment CDI equations, presented here for adult exposures, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.3 Noncarcinogenic for Age-adjusted
The recreational soil/sediment CDI equations, presented here for age-adjusted exposures, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.4 Carcinogenic
The recreational soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.5 Mutagenic
The recreational soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.6 Vinyl Chloride - Carcinogenic
The recreational soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.7 Trichloroethylene - Carcinogenic and Mutagenic
The recreational soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.7.1.8 Supporting Equations for Recreational Soil/Sediment
Child Supporting Equations.
Adult Supporting Equations.
Age-adjusted Supporting Equations.
4.7.2 Recreator Surface Water
This receptor is exposed to chemicals that are present in surface water. Ingestion of water and dermal contact with water are appropriate pathways. Dermal contact with surface water is only considered for analytes determined to be within the effective predictive domain as described in Section 4.11.8. Inhalation is not considered due to dilution from mixing with outdoor air.
4.7.2.1 Noncarcinogenic Child
The surface water CDI equations, presented here for child exposures, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.2 Noncarcinogenic Adult
The surface water CDI equations, presented here for adult exposures, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.3 Noncarcinogenic Age-adjusted
The surface water CDI equations, presented here for age-adjusted exposures, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.4 Carcinogenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.5 Mutagenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.6 Vinyl Chloride - Carcinogenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.7 Trichloroethylene - Carcinogenic and Mutagenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of water and
dermal contact with water.
4.7.2.8 Supporting Equations for Recreation Surface Water
Child Supporting Equations.
Adult Supporting Equations.
Age-adjusted Supporting Equations.
4.8 Farmer
4.8.1 Farmer Direct Consumption of Agricultural Products
The farmer scenario should be considered an extension of the resident scenario and evaluate consumption of farm products for a subsistence farmer. Like the resident, the farmer assumes the receptor will be exposed via the consumption of home grown produce (100% of fruit and vegetables are from the farm). In addition to produce, 100% of consumption of the following are also considered to be from the farm: beef and milk. All feed (100%) for farm products is considered to have been grown on contaminated portions of the site. For these farm products, risk-based CDIs are provided for the farm product itself (vegetables, beef, and milk). Also like the resident, age-adjusted intake equations were developed for all of the consumption equations to account for changes in intake as the receptor ages.
4.8.1.1 Concentration in Produce
4.8.1.1.1 Noncarcinogenic
The ingestion of produce equation, presented here, contains the following exposure route:
consumption of produce.
4.8.1.1.2 Carcinogenic
The ingestion of produce equation, presented here, contains the following exposure route:
consumption of produce.
4.8.1.2 Concentration in Dairy
4.8.1.2.1 Noncarcinogenic
The ingestion of dairy equation, presented here, contains the following exposure route:
consumption of dairy.
4.8.1.2.2 Carcinogenic
The ingestion of dairy equation, presented here, contains the following exposure route:
consumption of dairy.
4.8.1.3 Concentration in Beef
4.8.1.3.1 Noncarcinogenic
The ingestion of beef equation, presented here, contains the following exposure route:
consumption of beef.
4.8.1.3.2 Carcinogenic
The ingestion of beef equation, presented here, contains the following exposure route:
consumption of beef.
4.8.2 Farmer Direct Consumption of Agricultural Products - Back-calculated to Water
4.8.2.1 Back-calculated Concentration in Water Only - Produce
4.8.2.1.1 Noncarcinogenic
consumption of produce.
4.8.2.1.2 Carcinogenic
consumption of produce.
4.8.2.2 Back-calculated Concentration in Water Only - Dairy
4.8.2.2.1 Noncarcinogenic
consumption of dairy.
4.8.2.2.2 Carcinogenic
consumption of dairy.
4.8.2.3 Back-calculated Concentration in Water Only - Beef
4.8.2.3.1 Noncarcinogenic
consumption of beef.
4.8.2.3.2 Carcinogenic
consumption of beef.
4.8.3 Farmer Direct Consumption of Agricultural Products - Back-calculated to Soil
4.8.3.1 Back-calculated Concentration in Soil Only - Produce
4.8.3.1.1 Noncarcinogenic
consumption of produce.
4.8.3.1.2 Carcinogenic
consumption of produce.
4.8.3.2 Back-calculated Concentration in Soil Only - Dairy
4.8.3.2.1 Noncarcinogenic
consumption of dairy.
4.8.3.2.2 Carcinogenic
consumption of dairy.
4.8.3.3 Back-calculated Concentration in Soil Only - Beef
4.8.3.3.1 Noncarcinogenic
consumption of beef.
4.8.3.3.2 Carcinogenic
consumption of beef.
4.9 Soil to Groundwater
The soil migration to groundwater risk scenario is used to determine risk from groundwater exposure based on concentration in soil. Migration of contaminants from soil to groundwater can be envisioned as a two-stage process: (1) release of contaminant from soil to soil leachate and (2) transport of the contaminant through the underlying soil and aquifer to a receptor well. The soil to groundwater scenario considers both of these fate and transport mechanisms. The groundwater concentration is determined using a known concentration in soil, chemical specific Kd, and a dilution attenuation factor to obtain a risk or hazard. The soil to groundwater media option is included in both resident and indoor worker land use scenarios as they both model tapwater risks.
The risks and hazards determined in the soil migration to groundwater scenario are all based on three phases (vapor, soil and water).
Kds are from the Soil Screening Guidance Exhibit C-4. According to Appendix C,
"Exhibit C-4 provides pH-specific soil-water partition coefficients (Kd) for metals. Site-specific soil pH measurements can be used to select appropriate Kd values for these metals. Where site-specific soil pH values are not available, values corresponding to a pH of 6.8 should be used."If a metal is not listed in Exhibit C-4, Kds were taken from Baes, C. F. 1984. Kds for organic componds are calculated from Koc and the fraction of organic carbon in the soil (foc). Kds for metals are listed below.
Chemical CAS Reference Aluminum 7429-90-5 Baes, C.F. 1984 Antimony (metallic) 7440-36-0 SSG 9355.4-23 July 1996 Arsenic, Inorganic 7440-38-2 SSG 9355.4-23 July 1996 Barium 7440-39-3 SSG 9355.4-23 July 1996 Beryllium and compounds 7440-41-7 SSG 9355.4-23 July 1996 Boron and Borates Only 7440-42-8 Baes, C.F. 1984 Bromate 15541-45-4 Baes, C.F. 1984 Cadmium (Diet) 7440-43-9 SSG 9355.4-23 July 1996 Cadmium (Water) 7440-43-9 SSG 9355.4-23 July 1996 Chlorine 7782-50-5 Baes, C.F. 1984 Chromium (III) (Insoluble Salts) 16065-83-1 SSG 9355.4-23 July 1996 Chromium Salts 0-00-3 Baes, C.F. 1984 Chromium VI (chromic acid mists) 18540-29-9 SSG 9355.4-23 July 1996 Chromium VI (particulates) 18540-29-9 SSG 9355.4-23 July 1996 Chromium, Total (1:6 ratio Cr VI: Cr III) 7440-47-3 SSG 9355.4-23 July 1996 Cobalt 7440-48-4 Baes, C.F. 1984 Copper 7440-50-8 Baes, C.F. 1984 Cyanide (CN-) 57-12-5 SSG 9355.4-23 July 1996 Fluoride 16984-48-8 Surrogate Value from Fluorine (Soluble Fluoride) Fluorine (Soluble Fluoride) 7782-41-4 Baes, C.F. 1984 Hydrogen Cyanide (HCN) 74-90-8 Surrogate value from Cyanide Iron 7439-89-6 Baes, C.F. 1984 Lead and Compounds 7439-92-1 Baes, C.F. 1984 Lithium 7439-93-2 Baes, C.F. 1984 Magnesium 7439-95-4 Baes, C.F. 1984 Manganese (Diet) 7439-96-5 Baes, C.F. 1984 Manganese (Water) 7439-96-5 Baes, C.F. 1984 Mercury (elemental) 7439-97-6 SSG 9355.4-23 July 1996 Mercury, Inorganic Salts 0-01-7 SSG 9355.4-23 July 1996 Molybdenum 7439-98-7 Baes, C.F. 1984 Nickel Soluble Salts 7440-02-0 SSG 9355.4-23 July 1996 Phosphorus, White 7723-14-0 Baes, C.F. 1984 Selenium 7782-49-2 SSG 9355.4-23 July 1996 Silver 7440-22-4 SSG 9355.4-23 July 1996 Sodium 7440-23-5 Baes, C.F. 1984 Sodium Fluoride 7681-49-4 Surrogate Value from Fluorine (Soluble Fluoride) Strontium, Stable 7440-24-6 Baes, C.F. 1984 Thallium (Soluble Salts) 7440-28-0 SSG 9355.4-23 July 1996 Thorium 0-23-2 Baes, C.F. 1984 Tin 7440-31-5 Baes, C.F. 1984 Titanium 7440-32-6 Baes, C.F. 1984 Uranium (Soluble Salts) 0-23-8 Baes, C.F. 1984 Vanadium and Compounds 0-06-6 SSG 9355.4-23 July 1996 Vanadium, Metallic 7440-62-2 SSG 9355.4-23 July 1996 Zinc (Metallic) 7440-66-6 SSG 9355.4-23 July 1996 Zirconium 7440-67-7 Baes, C.F. 1984 Because Kds vary greatly by soil type, it is highly recommended that site-specific Kds be determined and used to calculate grounwater concentration.
The more protective of the carcinogenic and noncarcinogenic groundwater concentration is selected to calculate the risk/hazard.
4.9.1 Noncarcinogenic Tapwater Equations for SSLs
The groundwater concentration calculated using method 1 are used to calculate the tapwater chronic daily intake equations, presented in Section 4.1.3 for volatiles and non-volatiles. If the contaminant is a volatile, ingestion, dermal and inhalation exposure routes are considered. If the contaminant is not a volatile, only ingestion and dermal are considered.
4.9.2 Carcinogenic Tapwater Equations for SSLs
The groundwater concentration calculated using method 2 are used to calculate the tapwater chronic daily intake equations, presented in Section 4.1.3 for volatiles and non-volatiles. Sections 4.1.3.5, 4.1.3.6, and 4.1.3.7 present the mutagenic, vinyl chloride, and trichloroethylene equations, respectively. If the contaminant is a volatile, then ingestion, dermal, and inhalation exposure routes are considered. If the contaminant is not a volatile, only ingestion and dermal are considered.
4.9.3 Indoor Worker Noncarcinogenic Tapwater Equations for SSLs
The tapwater equations, presented in Section 4.4.3, are used to calculate the noncarcinogenic risk for volatiles and non-volatiles. If the contaminant is a volatile, ingestion, dermal and inhalation exposure routes are considered. If the contaminant is not a volatile, only ingestion and dermal are considered.
4.9.4 Indoor Worker Carcinogenic Tapwater Equations for SSLs
The tapwater equations, presented in Section 4.4.3, are used to calculate the carcinogenic risk for volatiles and non-volatiles. If the contaminant is a volatile, then ingestion, dermal, and inhalation exposure routes are considered. If the contaminant is not a volatile, only ingestion and dermal are considered.
4.9.5 Method 1: Concentration in Groundwater from Concentration in Soil
Method 1 employs a partitioning equation for migration to groundwater and defaults are provided. This method is used for the default soil to groundwater output in the calculator.
method 1 - partitioning
4.9.6 Method 2: Concentration in Groundwater from Concentration in Soil
Method 2 employs a mass-limit equation for migration to groundwater and site-specific information is required. This method can be used in the site-specific calculator portion of this website.
method 2 - mass loading
4.9.7 Determination of the Dilution Attenuation Factor
The default risk/hazard values are based on a dilution attenuation factor of 1. If one wishes to use the calculator to calculate risks or hazards using the SSL guidance for a source up to 0.5 acres, then a dilution attenuation factor of 20 can be used. If all of the parameters needed to calculate a site-specific dilution attenuation factor are known, they may be entered.
dilution attenuation factor
4.10 Trespasser
The trespasser exposure scenario and assumptions should be used whenever there is a risk of an unauthorized person accessing the site for a limited period of time. Trespassers could be exposed to any surface water bodies, sediment, the top two feet of soil, and potentially combined shallow and deep soil if deep soil is brought to the surface from construction or excavation activities. Other routes of exposure would be on a site-specific basis and preapproved by DNREC-RS. The trespasser exposure scenario assumes an adolescent age of 6 to 16 years old. It is assumed the trespasser would be exposed to the shallow soil (or sediment) for 58 days per year (exposure frequency) and 3.9 hours per day (exposure time). These assumptions are derived from Table 16-1, Recommended Values for Activity Patterns - Time Outdoors (total), in EPA's Exposure Factors Handbook: 2011 Edition.
The traditional vinyl chloride equations are not appropriate for the trespasser scenario. As the trespasser is identified as a teenager, there is no child exposure. The traditional vinyl chloride equations include a non-prorated child exposure and a prorated lifetime exposure term. Both terms are required to address a lifetime exposure. Equations do not currently exist to address exposure for only the teenager.
DNREC-RS does not use DE RAC to calculate potential risk to vinyl chloride exposure for the trespasser scenario in soil, sediment, and surface water. If vinyl chloride is the primary driver, please contact RS on how to evaluate the trespasser exposure scenario for the potential risk to vinyl chloride in the soil, sediment, and surface water. Please refer to the Guidance for Human Health Risk Assessments Under HSCA for more specific information.
4.10.1 Trespasser Soil/Sediment
This receptor spends time outside on property that is contaminated. The trespasser is assumed to be exposed to contaminants via the following pathways: incidental ingestion of soil, dermal contact with contaminants in soil, and inhalation of volatiles and fugitive dust.
4.10.1.1 Noncarcinogenic for Teenager
The trespasser soil/sediment CDI equations, presented here for child exposures, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.10.1.2 Carcinogenic
The trespasser soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.10.1.3 Mutagenic
The trespasser soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.10.1.4 Trichloroethylene - Carcinogenic and Mutagenic
The trespasser soil/sediment CDI equations, presented here, contain the following exposure routes:
incidental ingestion of soil/sediment,
inhalation of particulates emitted from soil/sediment, and
dermal contact with soil/sediment.
4.10.2 Trespasser Surface Water
This receptor is exposed to chemicals that are present in surface water. Ingestion of water and dermal contact with water are appropriate pathways. Dermal contact with surface water is only considered for analytes determined to be within the effective predictive domain as described in Section 4.11.8. Inhalation is not considered due to dilution from mixing with outdoor air.
4.10.2.1 Noncarcinogenic for Teenager
The surface water CDI equations, presented here for child exposures, contain the following exposure routes:
ingestion of surface water,
dermal contact with surface water, and
4.10.2.2 Carcinogenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of surface water,
dermal contact with surface water, and
4.10.2.3 Mutagenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of surface water,
dermal contact with surface water, and
4.10.2.4 Trichloroethylene - Carcinogenic and Mutagenic
The surface water CDI equations, presented here, contain the following exposure routes:
ingestion of surface water,
dermal contact with surface water, and
4.11 Supporting Equations and Parameter Discussion
There are two inhalation variables in the above CDI equations that require further explanation: the particulate emission factor (PEF) and the volatilization factor (VF). Also there are supporting equations and practices presented for the dermal exposure to water route.
4.11.1 Particulate Emission Factor (PEF)
Inhalation of contaminants adsorbed to respirable particles (PM10) was assessed using a default PEF equal to 1.36 x 109m3/kg. This equation relates the contaminant concentration in soil with the concentration of respirable particles in the air due to fugitive dust emissions from contaminated soils. The generic PEF was derived using default values that correspond to a receptor point concentration of approximately 0.76 ug/m3. The relationship is derived by Cowherd (1985) for a rapid assessment procedure applicable to a typical hazardous waste site, where the surface contamination provides a relatively continuous and constant potential for emission over an extended period of time (e.g. years). This represents an annual average emission rate based on wind erosion that should be compared with chronic health criteria; it is not appropriate for evaluating the potential for more acute exposures. Definitions of the input variables are in Section 6.
With the exception of specific heavy metals, the PEF does not appear to significantly affect most soil screening levels. The equation forms the basis for deriving a generic PEF for the inhalation pathway. For more details regarding specific parameters used in the PEF model, refer to Soil Screening Guidance: Technical Background Document. The use of alternate values on a specific site should be justified and presented in an Administrative Record if considered in CERCLA remedy selection.
Note: the generic PEF evaluates wind-borne emissions and does not consider dust emissions from traffic or other forms of mechanical disturbance that could lead to greater emissions than assumed here.
4.11.2 Vehicle traffic-driven Particulate Emission Factor (PEFsc)
The equation to calculate the subchronic particulate emission factor (PEFsc) is significantly different from the residential and non-residential PEF equations. The PEFsc focuses exclusively on emissions from truck traffic on unpaved roads, which typically contribute the majority of dust emissions during construction. This equation requires estimates of parameters such as the number of days with at least 0.01 inches of rainfall, the mean vehicle weight, and the sum of fleet vehicle distance traveled during construction.
The number of days with at least 0.01 inches of rainfall can be estimated using Exhibit 5-2 in the supplemental soil screening guidance. Mean vehicle weight (W) can be estimated by assuming the numbers and weights of different types of vehicles. For example, assuming that the daily unpaved road traffic consists of 20 two-ton cars and 10 twenty-ton trucks, the mean vehicle weight would be:
W = [(20 cars x 2 tons/car) + (10 trucks x 20 tons/truck)]/30 vehicles = 8 tons
The sum of the fleet vehicle kilometers traveled during construction (∑ VKT) can be estimated based on the size of the area of surface soil contamination, assuming the configuration of the unpaved road, and the amount of vehicle traffic on the road. For example, if the area of surface soil contamination is 0.5 acres (or 2,024 m2), and one assumes that this area is configured as a square with the unpaved road segment dividing the square evenly, the road length would be equal to the square root of 2,024 m2, 45 m (or 0.045 km). Assuming that each vehicle travels the length of the road once per day, 5 days per week for a total of 6 months, the total fleet vehicle kilometers traveled would be:
∑ VKT = 30 vehicles x 0.045 km/day x (52 weeks/year ÷ 2) x 5 days/wk = 175.5 km
4.11.3 Other than vehicle traffic-driven Particulate Emission Factor (PEF'sc)
Other than emissions from unpaved road traffic, the construction worker may also be exposed to particulate matter emissions from wind erosion, excavation soil dumping, dozing, grading, and tilling or similar operations PEF'sc. These operations may occur separately or concurrently and the duration of each operation may be different. For these reasons, the total unit mass emitted from each operation is calculated separately and the sum is normalized over the entire area of contamination and over the entire time during which construction activities take place. Equation E-26 in the supplemental soil screening guidance was used.
4.11.4 Infinite Source Chronic Volatilization Factor (VFulim)
The soil-to-air VF is used to define the relationship between the concentration of the contaminant in soil and the flux of the volatilized contaminant to air. VF is calculated from the equation below using chemical-specific properties and either site-measured or default values for soil moisture, dry bulk density, and fraction of organic carbon in soil. The Soil Screening Guidance: User's Guide describes how to develop site measured values for these parameters.
VF is only calculated for volatile organic compounds (VOCs). VOCs, for the purpose of this guidance, are chemicals with a Henry's Law constant of 1 x 10-5 atm-m3/mole or greater and with a molecular weight of less than 200 g/mole.
Diffusivity in Water (cm2/s)
Diffusivity in water can be calculated from the chemical's molecular weight and density, using the following correlation equation based on WATER9 (U.S. EPA, 2001):
If density is not available, diffusivity in water can be calculated using the correlation equation based on U.S. EPA (1987). The value for diffusivity in water must be greater than zero. No maximum limit is enforced.
Diffusivity in Air (cm2/s).
Diffusivity in air can be calculated from the chemical's molecular weight and density, using the following correlation equation based on WATER9 (U.S. EPA, 2001). If density is not available, an alternate equation is provided.:
For dioxins, furans, and dioxin-like PCBs, diffusivity in air should always be calculated from the molecular weight using the Graham's Law correlation equation based on December 2003 NAS Review Draft Part I: Volume 3 (pg 4-38). In this equation, the unknown diffusivity is solved by correlation to the known diphenyl diffusivity of 0.068 cm2/s and MW of 154 g/mol.
4.11.5 Mass-limit Chronic Volatilization Factor (VFmlim)
This Equation presents a model for calculating mass-limit SSLs for the outdoor inhalation of volatiles. This model can be used only if the depth and area of contamination are known or can be estimated with confidence. This equation is presented in the Soil Screening Guidance: User's Guide and the Supplemental Soil Screening Guidance.
Use of infinite source models to estimate volatilization can violate mass balance considerations, especially for small sources. To address this concern, the Soil Screening Guidance includes a model for calculating a mass-limit SSL that provides a lower limit to the SSL when the area and depth (i.e., volume) of the source are known or can be estimated reliably.
A mass-limit SSL represents the level of contaminant in the subsurface that is still protective when the entire volume of contamination volatilizes over the 30-year exposure duration and the level of contaminant at the receptor does not exceed the health-based limit.
To use mass-limit SSLs, determine the area and depth of the source, calculate both standard and mass-limit SSLs, compare them for each chemical of concern and select the higher of the two values.
Note that the equation requires a site-specific determination of the average depth of contamination in the source. Step 3, in the SSG, provides guidance for conducting subsurface sampling to determine source depth. Where the actual average depth of contamination is uncertain, a conservative estimate should be used (e.g., the maximum possible depth in the unsaturated zone). At many sites, the average water table depth may be used unless there is reason to believe that contamination extends below the water table. In this case SSLs do not apply and further investigation of the source in question is needed.
4.11.6 Unlimited Source Subchronic Volatilization Factor for Construction Worker (VFulim-sc)
Equation 5-14 of the supplemental soil screening guidance is appropriate for calculating the soil-to-air volatilization factor (VFsc) that relates the concentration of a contaminant in soil to the concentration in air resulting from volatilization. The equation for the subchronic dispersion factor for volatiles, Q/Csa, is presented in Equation 5-15 of the supplemental soil screening guidance. Q/Csa was derived using EPA's SCREEN3 dispersion model for a hypothetical site under a wide range of meteorological conditions. Unlike the Q/C values for the other scenarios, the Q/Csa for the construction scenario's simple site-specific approach can be modified only to reflect different site sizes between 0.5 and 500 acres; it cannot be modified for climatic zone. Site managers conducting a detailed site-specific analysis for the construction scenario can develop a site-specific Q/C value by running the SCREEN3 model. Further details on the derivation of Q/Csa can be found in Appendix E of the supplemental soil screening guidance.
4.11.7 Mass-limit Subchronic Volatilization Factor for Construction Worker (VFmlim-sc)
Since the equations developed to calculate SSLs for the inhalation of volatiles outdoors assume an infinite source, they can violate mass-balance considerations, especially for small sources. To address this concern, a mass-limit SSL equation for this pathway may be used (Equation 5-17 of the supplemental soils screening guidance). This equation can be used only when the volume (i.e., area and depth) of the contaminated soil source is known or can be estimated with confidence. As discussed above, the simple site-specific approach for calculating construction scenario SSLs uses the same emission model for volatiles as that used in the residential and non-residential scenarios. However, the conservative nature of this model (i.e., it assumes all contamination is at the surface) makes it sufficiently protective of construction worker exposures to volatiles.
4.11.8 Dermal Contact with Water Supporting Equations
RAGS Part E stresses the determination of whether a chemical is within the effective predictive domain (EPD) for the determination of dermal permeability constant (Kp) applicability. The DERAC output provides determination of whether or not a chemical is within the EPD. The DERAC output also displays our determination of the fraction of the chemical that is ultimately absorbed (FA). FA depends strongly on the chemical's lipophilic characteristic and molecular weight as expressed in the B parameter and the lag time. RAGS Part E has determined that dermal exposures contributing less than 10% of oral exposures are insignificant. However, the DERAC presents dermal PRGs regardless of contribution percent.
Effective Predictive Domain (EPD) is an area on a X/Y plot that symbolizes 95% statistical confidence levels of a regression equation to accurately estimate a dermal permeability constant (Kp). Only if a chemical is within the EPD, will the dermal route be calculated. The EPD is determined by investigating the predictive power of a regression equation using MW and log Kow values for a compound. If the intersection of the values falls within the designated plotted area, the chemical is determined to be in the EPD and the dermal route is calculated. The boundaries of MW and log Kow for the regression equation are presented below. The EPD is depicted in RAGS Part E in Appendix A; Exhibit A-1.
Dermal permeability constant (Kp cm/hr) values are either from EPI Suite or RAGS Part E in the chemical parameter hierarchy. Values from both sources are estimated. Each source has a different estimation model. The RAGS Part E model requires a log Kow and a MW, and if both log Kow and MW are available, a Kp is calculated. The RAGS Part E model is taken from the spreadsheet that accompanies RAGS Part E documentation and is reproduced below.
Fraction absorbed water (FA) is described in RAGS Part E in Appendix A. The FA term should be applied to account for the loss of chemical due to the desquamation of the outer skin layer and a corresponding reduction in the absorbed dermal dose. To determine FA values for the RSLs, the following regression analysis was performed. This analysis builds on the RAGS Part E data.
The dimensionless value (B) is the ratio of the permeability coefficient of a compound through the stratum corneum relative to its permeability coefficient across the viable epidermis (ve).
t* = Time to reach steady-state (hours) = 2.4 τevent
τevent = Lag time per event (hours/event)
4.11.10 Henry's Law Constant and Vapor Pressure Determination at Temperature Other Than 25°C
In site-specific mode for land uses that utilize soil or soil to groundwater media, users are given the option to the change groundwater temperature from the default of 25°C to a site-specific value. Since the unitless Henry's Law Constant (H') is derived based on the partial pressure of a gas in equilibrium with a liquid and the equilibrium changes when temperature changes, H' is changed to reflect the equilibrium at the given temperature. The equation below illustrates how H' is derived when groundwater temperature is changed. An EPA Fact Sheet describing the process can be found at Henrys Law Constant Fact Sheet.
The equation below illustrates how vapor pressure is derived when groundwater-soil system temperature is changed.
When changing the groundwater-soil system temperature, the criteria that determines whether a chemical is volatile or not may also change. The Henry's Law constants and vapor pressures that are used in DERAC calculations are based on standard laboratory conditions of 25°C. When the groundwater-soil system temperature is changed, the Henry's Law constants and vapor pressures will change accordingly. A volatile chemical at 25°C may not be volatile at a lower temperature. Conversely, a nonvolatile may become volatile at temperatures above 25°C. When the groundwater-soil system temperature is changed the DERAC calculator will provide the user with recalculated Henry's Law constants and vapor pressures. These values can be compared to the volatility status requirements presented in section 4.11.4. The DERAC calculator does not automatically change the volatility status of a chemical to reflect the user's change of the groundwater-soil system temperature. In site-specific user-provided mode of the calculator, the user may change the volatility status of a chemical if deemed appropriate by the user's regional risk assessor. Changing the volatility status can impact the inclusion of dermal exposure to soil, inhalation of volatiles during household use of water, and the soil to groundwater Method 1 calculations. See section 4.11.4 and 4.9.5 for more information.
Most of the risks are readily derived by referring to the above equations. However, there are some cases for which the standard equations do not apply and/or external adjustments to the equations are not recommended. These special case chemicals are discussed below.
5.1 Cadmium
The equations for Cadmium are based on the oral RfD for water, which is slightly more conservative (by a factor of 2) than the RfD for food. However, reasonable arguments could be made for applying an RfD for food (instead of the oral RfD for water) for some media, such as soils.
5.2 Lead
DNREC-RS does not use DE RAC to calculate potential risk to lead exposure. Please refer to the Guidance for Human Health Risk Assessments Under HSCA for more specific information on how to calculate risk to lead exposure.
5.3 Manganese
The IRIS RfD (0.14 mg/kg-day) for manganese is from all sources, including diet. The author of the IRIS assessment for manganese recommended that the dietary contribution from the normal U.S. diet (an upper limit of 5 mg/day) be subtracted when evaluating non-food (e.g. drinking water or soil) exposures to manganese, leading to a RfD of 0.071 mg/kg-day for non-food items. The explanatory text in IRIS further recommends using a modifying factor of 3 when calculating risks associated with non-food sources due to a number of uncertainties that are discussed in the IRIS file for manganese, leading to a RfD of 0.024 mg/kg-day. For more information regarding the Manganese RfD, users are advised to contact the author of the IRIS assessment on Manganese.
5.4 Vanadium Compounds
The oral RfD toxicity value for Vanadium, used in this website, is derived from the IRIS oral RfD for Vanadium Pentoxide by factoring out the molecular weight (MW) of the oxide ion. Vanadium Pentoxide (V205) has a molecular weight of 181.88. The two atoms of Vanadium contribute 56% of the MW. Vanadium Pentoxide's oral RfD of 9E-03 mg/kg-day multiplied by 56% gives a Vanadium oral RfD of 5.04E-03 mg/kg-day.
5.5 Uranium
The "Uranium Soluble Salts" risk calculations use the ATSDR intermediate MRL of 2E-04 mg/kg-day instead of the IRIS oral RfD of 3E-03 mg/kg-day. This is a deviation from the typical toxicity hierarchy. " In December 2016, the EPA Office of Superfund Remediation and Technology Innovation (OSRTI) announced its determination that the ATSDR intermediate MRL generally reflects a better scientific basis for assessing the chronic health risks of soluble uranium than the RfD currently available in IRIS." The rationale for this determination is summarized in an accompanying memorandum, which recommends use of the ATSDR intermediate MRL for assessing chronic and subchronic human exposures at Superfund sites nationwide.
5.6 Chromium (VI)
It is recommended that valence-specific data for chromium be collected when chromium is likely to be an important contaminant at a site, and when hexavalent chromium (Cr (VI)) may exist. For Cr(VI), IRIS shows an air unit risk of 1.2E-2 per (µg/m3). While the exact ratio of Cr(VI) to Cr(III) in the data used to derive the IRIS air unit risk value is not known, it is likely that both Cr(VI) and Cr(III) were present. The risk calculated using the IRIS air unit risk assume that the Cr(VI) to Cr(III) ratio is 1:6. Because of various sources of uncertainty, this assumption may overestimate or underestimate the risk calculated. Users are invited to review the document "Toxicological Review of Hexavalent Chromium" in support of the summary information on Cr(VI) on IRIS to determine whether they believe this ratio applies to their projects and to consider consulting with the DNREC Remediation Section.
The default Cr(VI) specific value (assuming 100% Cr(VI)) is derived by multiplying the IRIS Cr(VI) value by 7. This is considered to be a health-protective assumption, and is also consistent with the State of California's interpretation of the Mancuso study that forms the basis of Cr(VI)'s estimated carcinogenic potency.
If you are working on a chromium site, you may want to contact the appropriate regulatory officials in your region to determine what their position is on this issue.
The Maximum Contaminant Level (MCL) of 100 µg/L for "Chromium (total)", from the EPA's MCL listing is applied to the "Chromium, Total" analyte on this website.
Tier 3 sources were used to derive the screening levels for Cr(VI).
The New Jersey Department of Environmental Protection (NJDEP) determined that Cr(VI) by ingestion is likely to be carcinogenic in humans. NJDEP derived an oral carcinogenic slope factor, based on carcinogenic bioassays conducted by the National Toxicology Program (http://www.state.nj.us/dep/dsr/chromium/soil-cleanup-derivation.pdf). The New Jersey assessment did not make a determination that Cr(VI) was mutagenic by mode of action for carcinogenesis.
EPA's Office of Pesticide Programs (OPP) made a determination that Cr(VI) has a mutagenic mode of action for carcinogenesis in all cells regardless of type, following administration via drinking water. OPP recommended that Age-Dependent Adjustment Factors (ADAFs) be applied when assessing carcinogenic risks from early-life exposure (< 16 years of age). This determination was reviewed by OPP's carcinogenic Assessment Review Committee and published in a peer review journal).
Therefore, in 2009 the Tier III NJDEP value was adopted and the OPP recommendation with respect to mutagenicity. More recently, in 2011, external peer reviewers provided input on the EPA's Office of Research and Development Integrated Risk Information System draft Toxicological Review of Hexavalent Chromium (http://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=221433). The majority of reviewers questioned the evidence used to support a mutagenic mode of action for carcinogenesis for Cr(VI). Furthermore, in 2011 California Environmental Protection Agency finalized its drinking water Public Health Goal for Cr(VI). CalEPA's Technical Support Document concluded in numerous studies that Cr(VI) is both genotoxic and mutagenic. (http://www.oehha.ca.gov/water/phg/072911Cr6PHG.html)
Therefore, the DERAC acknowledges that there is uncertainty associated with the assessment of hexavalent chromium. However, no updated consensus IRIS assessment (Tier I) has yet appeared, and chromium is still under review by the IRIS program. With respect to risk, the more health-protective approach of applying ADAFs for early life exposure via ingestion, dermal and inhalation was used to calculate screening levels for all exposure pathways. Application of ADAFs for all exposure pathways results in more health-protective screening levels.
5.7 Aminodinitrotoluenes
The IRIS oral RfD of 2E-03 mg/kg-day for 2,4-Dinitrotoluene is used as a surrogate for 2-Amino-4,6-Dinitrotoluene and 4-Amino-2,6-Dinitrotoluene.
5.8 PCBs and Aroclors
In the DERAC database there are three distinct types of PCBs: Aroclors, individual PCB congeners, and risk/persistence-based PCBs. The PCB congeners are evaluated as dioxin-like, using dioxin TEFs, as discussed in section 2.3. The risk/persistence-based PCB toxicity values come from the IRIS summary. In that summary, high, low, and lowest risk and persistence human oral slope factor tiers are given. Below is the DERAC interpretation of this information.
TIERS OF HUMAN ORAL SLOPE FACTORS FOR ENVIRONMENTAL PCBs Media High Low Lowest Food Yes No No Soil Yes No No Sediment Yes No No Tapwater No Yes No Surface Water No Yes No Air Yes Yes Yes The IRIS Profile offers various criteria for the assignment of Aroclors into risk/persistence tiers. When congeners with more than four chlorines comprise less than one-half of a percent of total PCBs, the lowest risk/persistence tier is appropriate. Aroclor 1016 has virtually no congeners with more than four chlorines and is assigned to the lowest risk/persistence tier (EPA 1996). (Chlorination data and other physicochemical parameters can be found in section 4 of the ATSDR Profile.) Most of the criteria for assignment to the high risk/persistence tier are met by the other Aroclors in the DERAC as they are typically assessed at environmental sites. In addition to the degree of chlorination, these criteria include: food chain exposure; sediment or soil ingestion; dust or aerosol inhalation; dermal exposure; presence of dioxin-like, tumor-promoting, or persistent congeners; and early-life exposure (all pathways and mixtures). These are default recommendations for purposes of determining risk. The table below provides the assignment of Aroclors to risk/persistence tiers for the DERAC.
TIERS OF HUMAN ORAL SLOPE FACTORS FOR ENVIRONMENTAL PCBs Aroclor High Low Lowest 1016 No No Yes 1221 Yes No No 1232 Yes No No 1242 Yes No No 1248 Yes No No 1254 Yes No No 1260 Yes No No Aroclor 5460 toxicity is determined in a PPRTV independently from the IRIS assessment.
If risk assessors believe that the form of PCB and the environmental route at a specific site warrant a different assignment of risk/persistence category, they may consult with regional risk assessors on site-specific cases.
5.9 Xylenes
The IRIS oral RfD of 2E-01 mg/kg-day for xylene, mixture is used as a surrogate for the 3 xylene congeners. The earlier RfD values for some xylene isomers were withdrawn from our electronic version of HEAST. Also, the IRIS inhalation RfC of 1E-01 mg/m3 for xylene, mixture is used as a surrogate for the 3 xylene congeners.
5.10 Arsenic
Arsenic screening levels for ingestion of soil are now calculated with the relative bioavailability factor (RBA) of 0.6. The RBA can be adjusted using the calculator in site-specific/user-provided mode the same way toxicity values can be changed. The RBA for soil ingestion is shown in the calculator output. The 2012 document, Compilation and Review of Data on Relative Bioavailability of Arsenic in Soil provides supporting information.
Absolute bioavailability can be thought of as the absorption fraction. Relative bioavailability accounts for differences in the bioavailability of a contaminant between the medium of exposure (e.g., soil) and the media associated with the toxicity value (e.g., the arsenic RfD and CSF are derived from drinking water studies). The 60% oral RBA for arsenic in soil is empirically-based. It represents an upper-bound estimate from numerous studies where the oral RBA of soil-borne arsenic in samples collected from across the U.S. was experimentally determined against the water-soluble form. This RBA does not apply to dermal exposures to arsenic in soil for which the absorbed dose is calculated using a dermal absorption fraction (ABSd) of 0.03 (Exhibit 3-4 of USEPA, 2004).
5.11 Total Petroleum Hydrocarbons (TPHs)
Traditionally, hydrocarbon-impacted soils at sites contaminated by releases of petroleum fuels have been managed based on their total petroleum hydrocarbon (TPH) content. TPH refers to the total mass of hydrocarbons present without identifying individual compounds. In practice, TPH is defined by the analytical method that is used to measure the hydrocarbon content in contaminated media. Since the hydrocarbon extraction efficiency is not identical for each method, the same sample analyzed by different TPH methods will produce different TPH concentrations.
The hazard and health risk assessments that are typically conducted to support risk management decisions at contaminated sites generally require some level of understanding of the hydrocarbon chemical composition present in the contaminated media. Traditional TPH measurement techniques, however, provide no specific information about the detected hydrocarbons. Because TPH is not a consistent entity, the assessment of health effects and development of toxicity values for mixtures of hydrocarbons are problematic. In fact, many risk assessors prefer to analyze and assess the individual chemical constituents rather than rely on TPH data; consult with the DNREC Remediation Section for site-specific recommendations. In cases where TPH data are used, more details about the provisional TPH toxicity values are provided below.
In 2009, the Superfund Health Risk Technical Support Center (NCEA-Cincinnati) published a document that provides the data, methods, and assumptions for deriving Provisional Peer-Reviewed Toxicity Values (PPRTVs) for six fractions of petroleum hydrocarbons. The six TPH fractions were assigned representative compounds for determination of toxicity values and chemical-specific parameters. In addition, there are nine accompanying derivation support documents for n-hexane, benzene, toluene, ethylbenzene, xylenes, commercial or practical grade hexane, midrange aliphatic hydrocarbon streams, white mineral oil, and high-flash aromatic naphtha.
The PPRTV (PDF) (60 pp, 678 K) paper was the principal source for the derivation of these values. The carbon ranges and representative compounds for the RfDs, RfCs, and chemical-specific parameters are listed in the table below. An average of the chemical-specific parameters for 2-methylnaphthalene and naphthalene was calculated for the medium aromatic fraction. This is because 2-methylnaphthalaene represents the RfD and naphthalene represents the RfC. The carbon ranges presented from an analytical laboratory may not exactly match the carbon ranges from the PPRTV assessment; the carbon ranges used are not intended to screen against DRO, GRO, ORO and RRO analysis.
TPH Fractions Number of Carbons Equivalent Carbon Number Index Representative Compound (RfD/RfC) Low aliphatic C5-C8 EC5-EC8 commercial hexane* Medium aliphatic C9-C18 EC>8-EC16 hydrocarbon streams** High aliphatic C19-C32 EC>16-EC35 white mineral oil Low aromatic C6-C8 EC6-EC<9 benzene Medium aromatic C9-C16 EC9-EC<22 2-methylnaphthalene/naphthalene High aromatic C17-C32 EC>22-EC35 fluoranthene *Both commercial hexane and n-hexane were considered, but commercial hexane was selected for the RfC as the value was derived more recently (2009 vs 2005) and is more protective (0.6 mg/m3 vs 0.7 mg/m3). The PPRTV paper recommends using this value, unless it is known that n-hexane accounts for >53% of the fraction. See p. 20 of the PPRTV.
**Since hydrocarbon streams was recommended in the PPRTV paper, n-nonane was selected to represent the chemical-specific parameters.
5.12 Mutagens
Some of the cancer causing analytes in this tool operate by a mutagenic mode of action for carcinogenesis. There is reason to surmise that some chemicals with a mutagenic mode of action, which would be expected to cause irreversible changes to DNA, would exhibit a greater effect in early-life versus later-life exposure. Cancer risk to children in the context of the U.S. Environmental Protection Agency's cancer guidelines (U.S. EPA, 2005 (PDF) (166 pp, 468 K)) includes both early-life exposures that may result in the occurrence of cancer during childhood and early-life exposures that may contribute to cancers later in life. In keeping with this guidance, separate cancer risk equations are presented for mutagens. The mutagen vinyl chloride has a unique set of equations. Consult Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens, EPA/630/R-03/003F, March 2005 (PDF) (126 pp, 1.78 MB) for further information.
The below table lists the chemicals considered to be carcinogenic by mutagenic mode of action for the purposes of the RSLs. Also provided in the table is a link to the source as to why the chemical is considered to be a mutagen.
Chemical CASRN Reference Acrylamide 79-06-1 IRIS Benz[a]anthracene 56-55-3 Benzo[a]pyrene* Benzidine 92-87-5 Supplemental Guidance Benzo[a]pyrene 50-32-8 Supplemental Guidance Benzo[b]fluoranthene 205-99-2 Benzo[a]pyrene* Benzo[k]fluoranthene 207-08-9 Benzo[a]pyrene* Chromium(VI) 18540-29-9 CalEPA and IRIS Chrysene 218-01-9 Benzo[a]pyrene* Coke Oven Emissions 8007-45-2 70 Federal Register 19992 Dibenz[a,h]anthracene 53-70-3 Supplemental Guidance Dibromo-3-chloropropane, 1,2- 96-12-8 PPRTV Dimethylbenz(a)anthracene, 7,12- 57-97-6 Supplemental Guidance Ethylene Oxide 75-21-8 IRIS Indeno[1,2,3-cd]pyrene 193-39-5 Benzo[a]pyrene* Methylcholanthrene, 3- 56-49-5 Supplemental Guidance Methylene Chloride 75-09-2 IRIS Methylene-bis(2-chloroaniline), 4,4'- 101-14-4 PPRTV Nitrosodiethylamine, N- 55-18-5 Supplemental Guidance Nitrosodimethylamine, N- 62-75-9 Supplemental Guidance Nitroso-N-ethylurea, N- 759-73-9 Supplemental Guidance Nitroso-N-methylurea, N- 684-93-5 Supplemental Guidance Safrole 94-59-7 Supplemental Guidance Trichloroethylene 79-01-6 IRIS Trichloropropane, 1,2,3- 96-18-4 IRIS Urethane 51-79-6 Supplemental Guidance Vinyl Chloride 75-01-4 Supplemental Guidance * Please see section 2.4.6 of this user guide regarding Relative Potency Factors (RPFs).
5.13 Trichloroethylene (TCE)
In order to make the calculator display the correct results for TCE, the standard carcinogenic and mutagen equations needed to be combined. Since TCE requires the use of different toxicity values for carcinogenic and mutagen equations, it was decided to make a toxicity value adjustment factor for carcinogenic (CAF) and mutagens (MAF). The adjustments were done for oral (o) and inhalation (i). These adjustment factors are used in the TCE equation images presented in section 4. The equations used are presented below. The adjustment factors are based on the adult-based toxicity values.
TCE adjustment factor derivations
5.14 Mercuric Chloride (and other Mercury salts)
The IRIS RfC for "Mercury (elemental)" is used as a surrogate for "Mercuric Chloride (and other Mercury salts)". Note, that the VF for "Mercury (elemental)" is not used as a surrogate for "Mercuric Chloride (and other Mercury salts)". The use of the surrogate RfC would appear to be a violation of the chemical risk toxicity hierarchy because Cal EPA offers a RfC for Mercuric Chloride. However, the actual form of mercury evaluated for the Cal EPA RfC was elemental mercury. Since IRIS already had an RfC for "Mercury (elemental)", it was decided to use the tier 1 source over a tier 3 source.
5.15 Cyanide (CN-)
The IRIS RfC for "Hydrogen Cyanide" is used as a surrogate for "Cyanide (CN-)".
5.16 Thallic Oxide and Thallium Selenite
The oral RfD for thallic oxide, used in this website, is derived from the PPRTV oral RfD for thallium sulfate by molecular weight (MW) adjustments and stoichiometric calculations. Thallic oxide (Tl203) has a MW of 456.765 and thallium sulfate (Tl2SO4) has a MW of 504.82. To derive the oral RfD of 2E-05 mg/kg-day for thallic oxide, the thallium sulfate RfD of 2E-05 mg/kg-day is multiplied by the MW of thallic oxide (456.765) divided by the MW of thallium sulfate (504.82). The oral RfD for thallium selenite, used in this website, is derived from the PPRTV oral RfD for thallium by molecular weight (MW) adjustments and stoichiometric calculations. Thallium selenite (TlSe) has a MW of 283.34 and thallium (Tl) has a MW of 204.38. To derive the oral RfD of 1E-05 mg/kg-day for thallium selenite, the thallium RfD of 1E-05 mg/kg-day is multiplied by the MW of thallium selenite (283.34) divided by the MW of thallium (204.38).
5.17 Lanthanum Salts
The oral chronic RfDs for lanthanum salts, used in this website, are derived from the PPRTV oral chronic RfD for lanthanum by molecular weight (MW) adjustments and stoichiometric calculations. Lanthanum chloride, anhydrous (LaCl3) has a MW of 245.27, and lanthanum (La) has a MW of 138.91. To derive the chronic oral RfD of 2.83E-05 mg/kg-day for lanthanum chloride, anhydrous, the lanthanum RfD of 5E-05 mg/kg-day is multiplied by the MW of lanthanum (138.91) divided by the MW of lanthanum chloride, anhydrous (245.27). To derive the chronic oral RfD of 1.87E-05 mg/kg-day for lanthanum chloride heptahydrate, the lanthanum RfD of 5E-05 mg/kg-day is multiplied by the MW of lanthanum (138.91) divided by the MW of lanthanum chloride heptahydrate (371.37). To derive the chronic oral RfD of 1.60E-05 mg/kg-day for lanthanum nitrate hexahydrate, the lanthanum RfD of 5E-05 mg/kg-day is multiplied by the MW of lanthanum (138.91) divided by the MW of lanthanum nitrate hexahydrate (433.01). To derive the chronic oral RfD of 2.08E-05 mg/kg-day for lanthanum acetate hydrate, the lanthanum RfD of 5E-05 mg/kg-day is multiplied by the MW of lanthanum (138.91) divided by the MW of lanthanum acetate hydrate (334.05).
5.18 MCLs for Trihalomethanes and Haloacetic Acids
The individual trihalomethanes (bromodichloromethane; bromoform; dibromochloromethane, chloroform) all have the MCL of 80 µg/L listed in the HSCA Reporting Level table. However, 80 µg/L is the MCL for Total Trihalomethanes. Some of the individual haloacetic acids (dichloroacetic acid, trichloroacetic acid, chloroacetic acid, bromoacetic acid, and dibromoacetic acid) all have the MCL of 60 µg/L listed in the HSCA Reporting Level table. However, 60 µg/L is the MCL for Total haloacetic acids.
5.19 Perchlorate
The tapwater screening level for Perchlorate is different from the preliminary remedial goal (PRG) of 15 µg/L calculated by the Office of Solid Waste and Emergency Response in its January 8, 2009, guidance (PDF) . As described in the OSWER memorandum, the Agency issued an Interim Drinking Water Health Advisory (Interim Health Advisory) for exposure to perchlorate of 15 µg/L in water. A health advisory provides technical guidance to federal, state, and other public health officials on health effects, analytical methods and treatment technologies associated with drinking water contamination. The Interim Health Advisory for perchlorate was developed using EPA's RfD of 7E-04 mg/kg-day and representative body weight, as well as 90th percentile drinking water and national food exposure data for pregnant women in order to protect the most sensitive population identified by the National Research Council (NRC) (i.e., the fetuses of pregnant women who might have hypothyroidism or iodide deficiency).
The NCP (40 CFR 300.430(e)(2)(A)(1)) provides that when establishing acceptable exposure levels for use as remediation goals (for a Superfund site), consideration must be given to concentration levels to which the human population, including sensitive subgroups, may be exposed without adverse effects over a lifetime or part of a lifetime, incorporating an adequate margin of safety. As a result of the publication of the Interim Health Advisory for perchlorate, OSWER recommends that where no federal or state applicable or relevant and appropriate (ARAR) requirements exist under federal or state laws, 15 µg/L (or 15 ppb) is recommended as the PRG for perchlorate when making CERCLA site-specific cleanup decisions where there is an actual or potential drinking water exposure pathway. However, where State regulations qualify as ARARs for perchlorate, the remediation goals established shall be developed considering the State regulations that qualify as ARARs, as well as other factors cited in the NCP (see 40 CFR 300.430(e)(2)(i)(ff)). Final remediation goals and remedy decisions are made in accordance with 40 CFR300.430 (e) and (f) and associated provisions.
Preliminary remediation goals are the starting points in the development of final cleanup levels at sites. As at all sites addressed under the NCP, these goals may be modified, depending on physical characteristics of a site, State laws and guidance, and other site-specific factors, such as additional exposure routes.
The tapwater screening level is based on EPA's RfD and using standard RSL equations.
5.20 Styrene-acrylonitrile trimer (SAN Trimer)
Styrene-acrylonitrile trimer (SAN Trimer) is a by-product of specific manufacturing processes for polymers of styrene and acrylonitrile and a mixture of isomers formed by the condensation of two moles of acrylonitrile and one mole of styrene and has a molecular weight of 210. The mixture is composed of two structural forms: 4-cyano-1,2,3,4-tetrahydro-a-methyl1-naphthaleneacetonitrile (THNA, CASRN 57964-39-3) and 4-cyano-1,2,3,4-tetrahydro-1-naphthalenepropionitrile (THNP, CASRN 57964-40-6). The THNA form consists of four stereoisomers: cis-R-THNA (CASRN 142759-38-4), cis-S-THNA (CASRN 142759-39-5), trans-R-THNA (CASRN 142759-37-3), and trans-S-THNA (CASRN 142759-40-8). The THNP form consists of two stereoisomers: cis-THNP (CASRN 142681-91-2) and trans-THNP (CASRN 142681-92-3). The NTP report provides details regarding the structure and toxicity study for the mixture.
The SAN Trimer mixture is analyzed in environmental media using gas chromatography that yields three peaks. The total concentration corresponds to the total area of the three peaks. The Regional Screening Levels provide RSLs based on the oral Reference Dose for the SAN Trimer derived from the toxicity study described above. The PPRTV RfD used to derive the RSLs is based on the SAN Trimer mixture. The SAN Trimer structural isomers are listed separately in the RSL calculator but are the same values for the individual isomers. To evaluate the non-cancer toxicity of the SAN Trimer, compare the total concentration calculated based on the total of the three peaks to the RSL for either isomer.
5.21 cis- and trans-Chlordane Surrogate
According to an April 7, 2021 memo from the Office of Research and Development,
"..technical chlordane can be considered a suitable surrogate for oral, noncancer screening-level assessments of cis- and trans-chlordane".
Beginning in May 2021 the RSLs will use these surrogates.
Table 1. Toxicity Values
Symbol Definition (units) Default Reference RfDo Chronic Oral Reference Dose (mg/kg-day) Contaminant-specific EPA Superfund hierarchy RfC Chronic Inhalation Reference Concentration (mg/m3) Contaminant-specific EPA Superfund hierarchy CSFo Chronic Oral Slope Factor (mg/kg-day)-1 Contaminant-specific EPA Superfund hierarchy IUR Chronic Inhalation Unit Risk (µg/m3)-1 Contaminant-specific EPA Superfund hierarchy Table 2. Miscellaneous Variables
Symbol Definition (units) Default Reference Csoil concentration of contaminant in soil (mg/kg) User-input Entered by user Cg-water concentration of contaminant in groundwater (ug/L) User-input Entered by user Cs-water concentration of contaminant in surface water (ug/L) User-input Entered by user Cair concentration of contaminant in air (ug/m3) User-input Entered by user Cfish concentration of contaminant in fish (mg/kg) User-input Entered by user Cproduce concentration of contaminant in produce (mg/kg) User-input Entered by user Cdairy concentration of contaminant in dairy (mg/kg) User-input Entered by user Cbeef concentration of contaminant in beef (mg/kg) User-input Entered by user TR target risk (unitless) 1 × 10-6 Determined in this calculator THQ target hazard quotient (unitless) 1 Determined in this calculator LT Lifetime (years) 70 U.S. EPA 1989 (pg. 6-22) K Andelman Volatilization Factor (L/m3) 0.5 U.S. EPA 1991b (pg. 20) Kp permeability constant (cm/hour) Chemical-specific t* Time to reach steady-state (hours) Chemical-specific U.S. EPA 2004 (Page 3-4) τevent Lag time per event (hours/event) Chemical-specific U.S. EPA 2004 (Page 3-4) B Dimensionless ratio of the permeability coefficient of a compound through the stratum corneum relative to its permeability coefficient across the viable epidermis (unitless) Chemical-specific U.S. EPA 2004 (Page 3-4) FA Fraction absorbed water (unitless) Chemical-specific U.S. EPA 2004 (Page 3-4) ABSd Fraction of contaminant absorbed dermally from soil (unitless) Chemical-specific U.S. EPA 2004 (Exhibit 3-4) GIABS Fraction of contaminant absorbed in gastrointestinal tract (unitless) Note: if the GIABS is >50% then it is set to 100% for the calculation of dermal toxicity values. Chemical-specific U.S. EPA 2004 (Exhibit 4-1) H' Dimensionless Henry's Law Constant Contaminant-specific hierarchy selection in Section 2.4.2 ▵Hv,b Enthalpy of vaporization at the normal boiling point (cal/mol) Contaminant-specific hierarchy selection in Section 2.4.2 ▵Hv,gw Enthalpy of vaporization at temperature of groundwater (cal/mol) Contaminant-specific Determined in this calculator Tw Groundwater Temperatures (Kelvin) Site-specific Site-specific Tc Critical Temperatures (Kelvin) Contaminant-specific hierarchy selection in Section 2.4.2 Tb Normal Boiling Point (Kelvin) Contaminant-specific hierarchy selection in Section 2.4.2 n If (Tb/Tc < 0.57)
If (Tb/Tc > 0.71)
If (0.57 < Tb/Tc ≤ 0.71)n = 0.3
n = 0.41
n = (0.74 x Tb/Tc - 0.116)U.S. EPA VISL 2014 Table 3. Resident Soil Land Use Equation Variables
Symbol Definition (units) Default Reference CDIres-sol-nc-ing Resident Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIres-sol-nc-der Resident Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIres-sol-nc-inh Resident Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIres-sol-ca-ing Resident Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIres-sol-ca-der Resident Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIres-sol-ca-inh Resident Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator CDIres-sol-mu-ing Resident Soil Mutagenic Ingestion (mg/kg-day) Mutagen-specific Determined in this calculator CDIres-sol-mu-der Resident Soil Mutagenic Dermal (mg/kg-day) Mutagen-specific Determined in this calculator CDIres-sol-mu-inh Resident Soil Mutagenic Inhalation (ug/m3) Mutagen-specific Determined in this calculator CDIres-soil-ca-vc-ing Resident Soil Carcinogenic Vinyl Chloride Ingestion (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIres-soil-ca-vc-der Resident Soil Carcinogenic Vinyl Chloride Dermal (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIres-soil-ca-vc-inh Resident Soil Carcinogenic Vinyl Chloride Inhalation (ug/m3) Vinyl Chloride-specific Determined in this calculator CDIres-soil-tce-ing Resident Soil Carcinogenic and Mutagenic Trichloroethylene Ingestion (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIres-soil-tce-der Resident Soil Carcinogenic and Mutagenic Trichloroethylene Dermal (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIres-soil-tce-inh Resident Soil Carcinogenic and Mutagenic Trichloroethylene Inhalation (ug/m3) Trichloroethylene-specific Determined in this calculator BWres-a Body Weight - adult (kg) 80 U.S. EPA 2014 (Attachment 1) BWres-c Body Weight - child (kg) 15 U.S. EPA 2014 (Attachment 1) BW0-2 Body Weight - 0-2 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW2-6 Body Weight - 2-6 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW6-16 Body Weight - 6-16 Years (kg) 80 U.S. EPA 2014 (Attachment 1) BW16-26 Body Weight - 16-26 Years (kg) 80 U.S. EPA 2014 (Attachment 1) EDres Exposure Duration - adult + child (years) 26 U.S. EPA 2014 (Attachment 1) EDres-a Exposure Duration - adult (years) 20 U.S. EPA 2014 (Attachment 1) EDres-c Exposure Duration - child (years) 6 U.S. EPA 2014 (Attachment 1) ED0-2 Exposure Duration - 0-2 Years (years) 2 U.S. EPA 2014 (Attachment 1) ED2-6 Exposure Duration - 2-6 Years (years) 4 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration - 6-16 Years (years) 10 U.S. EPA 2014 (Attachment 1) ED16-26 Exposure Duration - 16-26 Years (years) 10 U.S. EPA 2014 (Attachment 1) EFres Exposure Frequency - adult + child (days/year) 350 U.S. EPA 2014 (Attachment 1) EFres-a Exposure Frequency - adult (days/year) 350 U.S. EPA 2014 (Attachment 1) EFres-c Exposure Frequency - child (days/year) 350 U.S. EPA 2014 (Attachment 1) EF0-2 Exposure Frequency - 0-2 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) EF2-6 Exposure Frequency - 2-6 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) EF6-16 Exposure Frequency - 6-16 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) EF16-26 Exposure Frequency - 16-26 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) ETres-a Resident Exposure Time - adult (hours/day) 24 The whole day ETres-c Resident Exposure Time - child (hours/day) 24 The whole day ETres Resident Exposure Time (hours/day) 24 The whole day ET0-2 Exposure Time - age segment 0-2 (hours/day) 24 The whole day ET2-6 Exposure Time - age segment 2-6 (hours/day) 24 The whole day ET6-16 Exposure Time - age segment 6-16 (hours/day) 24 The whole day ET16-26 Exposure Time - age segment 16-26 (hours/day) 24 The whole day IRSres-c Ingestion Rate - Child (mg/day) 200 U.S. EPA 2014 (Attachment 1) IRSres-a Ingestion Rate - Adult (mg/day) 100 U.S. EPA 2014 (Attachment 1) IRS0-2 Ingestion Rate - 0-2 years (mg/day) 200 U.S. EPA 2014 (Attachment 1) IRS2-6 Ingestion Rate - 2-6 years (mg/day) 200 U.S. EPA 2014 (Attachment 1) IRS6-16 Ingestion Rate - 6-16 years (mg/day) 100 U.S. EPA 2014 (Attachment 1) IRS16-26 Ingestion Rate - 16-26 years (mg/day) 100 U.S. EPA 2014 (Attachment 1) IFSres-adj Ingestion Rate - Age-adjusted (mg/kg) 36,750 Calculated using the age-adjusted intake factors equation IFSMres-adj Mutagenic Ingestion Rate - Age-adjusted (mg/kg) 166,833 Calculated using the mutagenic age-adjusted intake factors equation AFres-c Adherence factor-child (mg/cm2) 0.2 U.S. EPA 2014 (Attachment 1) AFres-a Adherence factor-adult (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) AF0-2 Adherence factor 0-2 years (mg/cm2) 0.2 U.S. EPA 2014 (Attachment 1) AF2-6 Adherence factor 2-6 years (mg/cm2) 0.2 U.S. EPA 2014 (Attachment 1) AF6-16 Adherence factor 6-16 years (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) AF16-26 Adherence factor 16-26 years (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) DFSres-adj Dermal contact factor- age-adjusted (mg/kg) 103,390 Calculated using the age-adjusted intake factors equation DFSMres-adj Mutagenic dermal contact factor- age-adjusted (mg/kg) 428,260 Calculated using the mutagenic age-adjusted intake factors equation SAres-c Surface area - child (cm2) 2373 U.S. EPA 2014 (Attachment 1) SAres-a Surface area - adult (cm2) 6032 U.S. EPA 2014 (Attachment 1) SA0-2 Surface area 0-2 years (cm2) 2373 U.S. EPA 2014 (Attachment 1) SA2-6 Surface area 2-6 years (cm2) 2373 U.S. EPA 2014 (Attachment 1) SA6-16 Surface area 6-16 years (cm2) 6032 U.S. EPA 2014 (Attachment 1) SA16-26 Surface area 16-26 (cm2) 6032 U.S. EPA 2014 (Attachment 1) ATres Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATres-c Averaging time - child (days/year) 365 x EDres-c U.S. EPA 2014 (Attachment 1) ATres-a Averaging time - adult (days/year) 365 x EDres U.S. EPA 2014 (Attachment 1) Table 4. Composite Worker Soil Land Use Equation Variables
Symbol Definition (units) Default Reference CDIw-sol-nc-ing Composite Worker Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-sol-nc-der Composite Worker Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-sol-nc-inh Composite Worker Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific Determined in this calculator CDIw-sol-ca-ing Composite Worker Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-sol-ca-der Composite Worker Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-sol-ca-inh Composite Worker Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator BWw Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDw Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFw Exposure Frequency (days/year) 250 U.S. EPA 2014 (Attachment 1) ETw Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) IRSw Ingestion Rate (mg/day) 100 U.S. EPA 2014 (Attachment 1) AFw Adherence factor (mg/cm2) 0.12 U.S. EPA 2014 (Attachment 1) SAw Surface Area (cm2) 3527 U.S. EPA 2014 (Attachment 1) ATw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATw-a Averaging time - adult (days/year) 365 x EDw U.S. EPA 2014 (Attachment 1) Table 5. Outdoor Worker Soil Land Use Equation Variables
Symbol Definition (units) Default Reference CDIow-sol-nc-ing Outdoor Worker Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIow-sol-nc-der Outdoor Worker Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIow-sol-nc-inh Outdoor Worker Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific Determined in this calculator CDIow-sol-ca-ing Outdoor Worker Soil Carcinogenic Ingestion (mg/kgday) Contaminant-specific Determined in this calculator CDIow-sol-ca-der Outdoor Worker Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIow-sol-ca-inh Outdoor Worker Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator BWow Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDow Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFow Exposure Frequency (days/year) 225 U.S. EPA 2014 (Attachment 1) ETow Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) IRSow Ingestion Rate (mg/day) 100 U.S. EPA 2014 (Attachment 1) AFow Adherence factor (mg/cm2) 0.12 U.S. EPA 2014 (Attachment 1) SAow Surface area (cm2) 3527 U.S. EPA 2014 (Attachment 1) ATow Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATow-a Averaging time - adult (days/year) 365 x EDow U.S. EPA 2014 (Attachment 1) Table 6. Indoor Worker Soil Land Use Equation Variables
Symbol Definition (units) Default Reference CDIiw-nc-ing Indoor Worker Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIiw-nc-inh Indoor Worker Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific Determined in this calculator CDIiw-ca-ing Indoor Worker Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIiw-ca-inh Indoor Worker Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator BWiw Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDiw Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFiw Exposure Frequency (days/year) 250 U.S. EPA 2014 (Attachment 1) ETiw Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) IRSiw Soil Ingestion Rate (mg/day) 50 U.S. EPA 2014 (Attachment 1) ATiw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATiw-a Averaging time - adult (days/year) 365 x EDiw U.S. EPA 2014 (Attachment 1) Table 7. Construction Worker Soil Land Use Equation Variables
Symbol Definition (units) Default Reference CDIcw-sol-nc-ing Construction Worker Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIcw-sol-nc-der Construction Worker Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIcw-sol-nc-inh Construction Worker Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific Determined in this calculator CDIcw-sol-ca-ing Construction Worker Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIcw-sol-ca-der Construction Worker Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIcw-sol-ca-inh Construction Worker Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator BWcw Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDcw Exposure Duration (years) 1 U.S. EPA 2014 (Attachment 1) EWcw Exposure (weeks/year) 50 based on 50 weeks per year (reasonable work season) DWcw Exposure (days/week) 5 based on 5 days per week for 50 weeks EFcw Exposure Frequency (days/year) EW x DW based on 5 days per week for 50 weeks ETcw Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) IRScw Ingestion Rate (mg/day) 330 U.S. EPA 2002 (Exhibit 1-2) AFcw Adherence factor (mg/cm2) 0.3 U.S. EPA 2002 (Exhibit 1-2) SAcw Surface area (cm2) 3527 U.S. EPA 2014 (Attachment 1) ATcw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATcw-a Averaging time - adult (days/year) 365 x EDcw U.S. EPA 2014 (Attachment 1) Table 8. Excavation Worker Soil Land Use Equation Variables
Symbol Definition (units) Default Reference CDIew-sol-nc-ing Excavation Worker Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIew-sol-nc-der Excavation Worker Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIew-sol-nc-inh Excavation Worker Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific Determined in this calculator CDIew-sol-ca-ing Excavation Worker Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIew-sol-ca-der Excavation Worker Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIew-sol-ca-inh Excavation Worker Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator BWew Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDew Exposure Duration (years) 1 U.S. EPA 2014 (Attachment 1) EFew Exposure Frequency (days/year) 20 based on 5 days per week for 4 weeks ETew Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) IRSew Ingestion Rate (mg/day) 330 U.S. EPA 2002 (Exhibit 1-2) AFew Adherence factor (mg/cm2) 0.3 U.S. EPA 2002 (Exhibit 1-2) SAew Surface area (cm2) 3527 U.S. EPA 2014 (Attachment 1) ATew Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATew-a Averaging time - adult (days/year) 365 x EDew U.S. EPA 2014 (Attachment 1) Table 9. Recreator Soil/Sediment Land Use Equation Variables
Symbol Definition (units) Default Reference CDIrec-sol-nc-ing Recreation Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIrec-sol-nc-der Recreation Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIrec-sol-nc-inh Recreation Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIrec-sol-ca-ing Recreation Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIrec-sol-ca-der Recreation Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIrec-sol-ca-inh Recreation Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator CDIrec-sol-mu-ing Recreation Soil Mutagenic Ingestion (mg/kg-day) Mutagen-specific Determined in this calculator CDIrec-sol-mu-der Recreation Soil Mutagenic Dermal (mg/kg-day) Mutagen-specific Determined in this calculator CDIrec-sol-mu-inh Recreation Soil Mutagenic Inhalation (ug/m3) Mutagen-specific Determined in this calculator CDIrec-soil-ca-vc-ing Recreation Soil Carcinogenic Vinyl Chloride Ingestion (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIrec-soil-ca-vc-der Recreation Soil Carcinogenic Vinyl Chloride Dermal (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIrec-soil-ca-vc-inh Recreation Soil Carcinogenic Vinyl Chloride Inhalation (ug/m3) Vinyl Chloride-specific Determined in this calculator CDIrec-soil-tce-ing Recreation Soil Carcinogenic and Mutagenic Trichloroethylene Ingestion (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIrec-soil-tce-der Recreation Soil Carcinogenic and Mutagenic Trichloroethylene Dermal (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIrec-soil-tce-inh Recreation Soil Carcinogenic and Mutagenic Trichloroethylene Inhalation (ug/m3) Trichloroethylene-specific Determined in this calculator BWrec-a Body Weight - adult (kg) 80 U.S. EPA 2014 (Attachment 1) BWrec-c Body Weight - child (kg) 15 U.S. EPA 2014 (Attachment 1) BW0-2 Body Weight - 0-2 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW2-6 Body Weight - 2-6 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW6-16 Body Weight - 6-16 Years (kg) 80 U.S. EPA 2014 (Attachment 1) BW16-26 Body Weight - 16-26 Years (kg) 80 U.S. EPA 2014 (Attachment 1) EDrec Exposure Duration - adult + child (years) 26 U.S. EPA 2014 (Attachment 1) EDrec-a Exposure Duration - adult (years) 20 U.S. EPA 2014 (Attachment 1) EDres-c Exposure Duration - child (years) 6 U.S. EPA 2014 (Attachment 1) ED0-2 Exposure Duration - 0-2 Years (years) 2 U.S. EPA 2014 (Attachment 1) ED2-6 Exposure Duration - 2-6 Years (years) 4 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration - 6-16 Years (years) 10 U.S. EPA 2014 (Attachment 1) ED16-26 Exposure Duration - 16-26 Years (years) 10 U.S. EPA 2014 (Attachment 1) EFrec Exposure Frequency - adult + child (days/year) 75 Reasonable Estimate EFrec-a Exposure Frequency - adult (days/year) 75 Reasonable Estimate EFrec-c Exposure Frequency - child (days/year) 75 Reasonable Estimate EF0-2 Exposure Frequency - 0-2 Years (days/year) 75 Reasonable Estimate EF2-6 Exposure Frequency - 2-6 Years (days/year) 75 Reasonable Estimate EF6-16 Exposure Frequency - 6-16 Years (days/year) 75 Reasonable Estimate EF16-26 Exposure Frequency - 16-26 Years (days/year) 75 Reasonable Estimate ETrec Exposure Time (hours/day) 1 Reasonable Estimate ETrec-c Exposure time - child (hours/day) 1 Reasonable Estimate ETrec-a Exposure time - adult (hours/day) 1 Reasonable Estimate ET0-2 Exposure time 0-2 years (hours/day) 1 Reasonable Estimate ET2-6 Exposure time 2-6 years (hours/day) 1 Reasonable Estimate ET6-16 Exposure time 6-16 years (hours/day) 1 Reasonable Estimate ET16-26 Exposure time 16-26 years (hours/day) 1 Reasonable Estimate IRSrec-c Ingestion Rate - Child (mg/day) 200 U.S. EPA 2014 (Attachment 1) IRSrec-a Ingestion Rate - Adult (mg/day) 100 U.S. EPA 2014 (Attachment 1) IRS0-2 Ingestion Rate - 0-2 years (mg/day) 200 U.S. EPA 2014 (Attachment 1) IRS2-6 Ingestion Rate - 2-6 years (mg/day) 200 U.S. EPA 2014 (Attachment 1) IRS6-16 Ingestion Rate - 6-16 years (mg/day) 100 U.S. EPA 2014 (Attachment 1) IRS16-26 Ingestion Rate - 16-26 years (mg/day) 100 U.S. EPA 2014 (Attachment 1) IFSrec-adj Ingestion Rate - Age-adjusted (mg/kg) 7,875 Calculated using the age-adjusted intake factors equation IFSMrec-adj Mutagenic Ingestion Rate - Age-adjusted (mg/kg) 35,750 Calculated using the mutagenic age-adjusted intake factors equation AFrec-c Adherence factor-child (mg/cm2) 0.2 U.S. EPA 2014 (Attachment 1) AFrec-a Adherence factor-adult (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) AF0-2 Adherence factor 0-2 years (mg/cm2) 0.2 U.S. EPA 2014 (Attachment 1) AF2-6 Adherence factor 2-6 years (mg/cm2) 0.2 U.S. EPA 2014 (Attachment 1) AF6-16 Adherence factor 6-16 years (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) AF16-26 Adherence factor 16-26 years (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) DFSrec-adj Dermal contact factor- age-adjusted (mg/kg) 22,155 Calculated using the age-adjusted intake factors equation DFSMrec-adj Mutagenic dermal contact factor- age-adjusted (mg/kg) 91,770 Calculated using the mutagenic age-adjusted intake factors equation SArec-c Surface area - child (cm2) 2373 U.S. EPA 2014 (Attachment 1) SArec-a Surface area - adult (cm2) 6032 U.S. EPA 2014 (Attachment 1) SA0-2 Surface area 0-2 years (cm2) 2373 U.S. EPA 2014 (Attachment 1) SA2-6 Surface area 2-6 years (cm2) 2373 U.S. EPA 2014 (Attachment 1) SA6-16 Surface area 6-16 years (cm2) 6032 U.S. EPA 2014 (Attachment 1) SA16-26 Surface area 16-26 (cm2) 6032 U.S. EPA 2014 (Attachment 1) ATrec Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATrec-c Averaging time - child (days/year) 365 x EDrec-c U.S. EPA 2014 (Attachment 1) ATrec-a Averaging time - adult (days/year) 365 x EDrec U.S. EPA 2014 (Attachment 1) Table 10. Recreator Surface Water Land Use Equation Variables
Symbol Definition (units) Default Reference CDIrec-water-nc-ing Recreation Surface Water Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIrec-water-nc-der Recreation Surface Water Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIrec-water-ca-ing Recreation Surface Water Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIrec-water-ca-der Recreation Surface Water Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIrec_water-mu-ing Recreation Surface Water Mutagenic Ingestion (mg/kg-day) Mutagen-specific Determined in this calculator CDIrec_water-mu-der Recreation Surface Water Mutagenic Dermal (mg/kg-day) Mutagen-specific Determined in this calculator CDIrec_water-ca-vc-ing Recreation Surface Water Carcinogenic Vinyl Chloride Ingestion (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIrec_water-ca-vc-der Recreation Surface Water Carcinogenic Vinyl Chloride Dermal (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIrec_water-tce-ing Recreation Surface Water Carcinogenic and Mutagenic Trichloroethylene Ingestion (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIrec_water-tce-der Recreation Surface Water Carcinogenic and Mutagenic Trichloroethylene Dermal (mg/kg-day) Trichloroethylene-specific Determined in this calculator BWrec-a Body Weight - adult (kg) 80 U.S. EPA 2014 (Attachment 1) BWrec-c Body Weight - child (kg) 15 U.S. EPA 2014 (Attachment 1) BW0-2 Body Weight - 0-2 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW2-6 Body Weight - 2-6 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW6-16 Body Weight - 6-16 Years (kg) 80 U.S. EPA 2014 (Attachment 1) BW16-26 Body Weight - 16-26 Years (kg) 80 U.S. EPA 2014 (Attachment 1) EDrec-a Exposure Duration - adult (years) 20 U.S. EPA 2014 (Attachment 1) EDrec-c Exposure Duration - child (years) 6 U.S. EPA 2014 (Attachment 1) ED0-2 Exposure Duration - 0-2 Years (years) 2 U.S. EPA 2014 (Attachment 1) ED2-6 Exposure Duration - 2-6 Years (years) 4 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration - 6-16 Years (years) 10 U.S. EPA 2014 (Attachment 1) ED16-26 Exposure Duration - 16-26 Years (years) 10 U.S. EPA 2014 (Attachment 1) EFrec-a Exposure Frequency - adult (days/year) 45 Region 4 Bulletin EFrec-c Exposure Frequency - child (days/year) 45 Region 4 Bulletin EF0-2 Exposure Frequency - 0-2 Years (days/year) 45 Region 4 Bulletin EF2-6 Exposure Frequency - 2-6 Years (days/year) 45 Region 4 Bulletin EF6-16 Exposure Frequency - 6-16 Years (days/year) 45 Region 4 Bulletin EF16-26 Exposure Frequency - 16-26 Years (days/year) 45 Region 4 Bulletin ETevent-rec-c Exposure Time - child (hours/event) 1 Reasonable Estimate ETevent-rec-a Exposure Time - adult (hours/event) 1 Reasonable Estimate ETevent-rec(0-2) Exposure Time (hours/event) 1 Reasonable Estimate ETevent-rec(2-6) Exposure Time (hours/event) 1 Reasonable Estimate ETevent-rec(6-16) Exposure Time (hours/event) 1 Reasonable Estimate ETevent-rec(16-26) Exposure Time (hours/event) 1 Reasonable Estimate EVrec-c Events - child (events/day) 1 Reasonable Estimate EVrec-a Events - adult (events/day) 1 Reasonable Estimate EV0-2 Events (events/day) 1 Reasonable Estimate EV2-6 Events (events/day) 1 Reasonable Estimate EV6-16 Events (events/day) 1 Reasonable Estimate EV16-26 Events (events/day) 1 Reasonable Estimate IRWrec-c Ingestion Rate - Child (L/hour) 0.12 Table 3.5 in EFH 2011 IRWrec-a Ingestion Rate - Adult (L/hour) 0.11 Time weighted average was calculated based on the upper percentile from Table 3.7 of EFH 2019 IRW0-2 Ingestion Rate - 0-2 years (L/hour) 0.12 Table 3.5 in EFH 2011 IRW2-6 Ingestion Rate - 2-6 years (L/hour) 0.12 Table 3.5 in EFH 2011 IRW6-16 Ingestion Rate - 6-16 years (L/hour) 0.124 Time weighted average was calculated based on the upper percentile from Table 3.7 of EFH 2019 IRW16-26 Ingestion Rate - 16-26 years (L/hour) 0.0985 Time weighted average was calculated based on the upper percentile from Table 3.7 of EFH 2019 IFWrec-adj Ingestion Rate - Age-adjusted (L/kg) 3.4 Calculated using the age-adjusted intake factors equation IFWMrec-adj Mutagenic Ingestion Rate - Age-adjusted (L/kg) 14 Calculated using the mutagenic age-adjusted intake factors equation SAres-c Surface area - child (cm2) 6,365 U.S. EPA 2014 (Attachment 1) SAres-a Surface area - adult (cm2) 19,652 U.S. EPA 2014 (Attachment 1) SA0-2 Surface area 0-2 years (cm2) 6,365 U.S. EPA 2014 (Attachment 1) SA2-6 Surface area 2-6 years (cm2) 6,365 U.S. EPA 2014 (Attachment 1) SA6-16 Surface area 6-16 years (cm2) 19,652 U.S. EPA 2014 (Attachment 1) SA16-26 Surface area 16-26 (cm2) 19,652 U.S. EPA 2014 (Attachment 1) DFWrec-adj Dermal contact factor- age-adjusted (cm2-event/kg) 335,655 Calculated using the age-adjusted intake factors equation DFWMrec-adj Mutagenic dermal contact factor- age-adjusted (cm2-event/kg) 1,053,210 Calculated using the mutagenic age-adjusted intake factors equation ATrec Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATrec-c Averaging time (days/year) 365 x EDrec-c U.S. EPA 2014 (Attachment 1) ATrec-a Averaging time (days/year) 365 x EDrec-a U.S. EPA 2014 (Attachment 1) Table 11. Resident Tapwater Land Use Equation Variables
Symbol Definition (units) Default Reference CDIwater-nc-ing Resident Tapwater (Groundwater) Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIwater-nc-der Resident Tapwater (Groundwater) Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIwater-nc-inh Resident Tapwater (Groundwater) Noncarcinogenic Inhalation (mg/m3) Contaminant-specific
Child, Adult and Age-adjusted SpecificDetermined in this calculator CDIwater-ca-ing Recreation Tapwater (Groundwater) Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIwater-ca-der Resident Tapwater (Groundwater) Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIwater-ca-inh Resident Tapwater (Groundwater) Carcinogenic Inhalation (µm3) Contaminant-specific Determined in this calculator CDIwater-mu-ing Resident Tapwater (Groundwater) Mutagenic Ingestion (mg/kg-day) Mutagen-specific Determined in this calculator CDIwater-mu-der Resident Tapwater (Groundwater) Mutagenic Dermal (mg/kg-day) Mutagen-specific Determined in this calculator CDIwater-mu-inh Resident Tapwater (Groundwater) Mutagenic Inhalation (µm3) Mutagen-specific Determined in this calculator CDIwater-ca-vc-ing Resident Tapwater (Groundwater) Carcinogenic Vinyl Chloride Ingestion (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIwater-ca-vc-der Resident Tapwater (Groundwater) Carcinogenic Vinyl Chloride Dermal (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIwater-ca-vc-inh Resident Tapwater (Groundwater) Carcinogenic Vinyl Chloride Inhalation (µm3) Vinyl Chloride-specific Determined in this calculator CDIwater-tce-ing Resident Tapwater (Groundwater) Carcinogenic and Mutagenic Trichloroethylene Ingestion (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIwater-tce-der Resident Tapwater (Groundwater) Carcinogenic and Mutagenic Trichloroethylene Dermal (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIwater-tce-inh Resident Tapwater (Groundwater) Carcinogenic and Mutagenic Trichloroethylene Inhalation (µm3) Trichloroethylene-specific Determined in this calculator BWres-a Body Weight - adult (kg) 80 U.S. EPA 2014 (Attachment 1) BWres-c Body Weight - child (kg) 15 U.S. EPA 2014 (Attachment 1) BW0-2 Body Weight - 0-2 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW2-6 Body Weight - 2-6 Years (kg) 15 U.S. EPA 2014 (Attachment 1) BW6-16 Body Weight - 6-16 Years (kg) 80 U.S. EPA 2014 (Attachment 1) BW16-26 Body Weight - 16-26 Years (kg) 80 U.S. EPA 2014 (Attachment 1) EDres Exposure Duration - adult + child (years) 26 U.S. EPA 2014 (Attachment 1) EDres-a Exposure Duration - adult (years) 20 U.S. EPA 2014 (Attachment 1) EDres-c Exposure Duration - child (years) 6 U.S. EPA 2014 (Attachment 1) ED0-2 Exposure Duration - 0-2 Years (years) 2 U.S. EPA 2014 (Attachment 1) ED2-6 Exposure Duration - 2-6 Years (years) 4 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration - 6-16 Years (years) 10 U.S. EPA 2014 (Attachment 1) ED16-26 Exposure Duration - 16-26 Years (years) 10 U.S. EPA 2014 (Attachment 1) EFres Exposure Frequency - adult + child (days/year) 350 U.S. EPA 2014 (Attachment 1) EFres-a Exposure Frequency - adult (days/year) 350 U.S. EPA 2014 (Attachment 1) EFres-c Exposure Frequency - child (days/year) 350 U.S. EPA 2014 (Attachment 1) EF0-2 Exposure Frequency - 0-2 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) EF2-6 Exposure Frequency - 2-6 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) EF6-16 Exposure Frequency - 6-16 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) EF16-26 Exposure Frequency - 16-26 Years (days/year) 350 U.S. EPA 2014 (Attachment 1) ETres Exposure Time (hours/day) 24 The whole day ETevent-res-c Exposure Time - child (hours/event) 0.54 U.S. EPA 2014 (Attachment 1) ETevent-res-a Exposure Time - adult (hours/event) 0.71 U.S. EPA 2014 (Attachment 1) ETevent-res(0-2) Exposure Time (hours/event) 0.54 U.S. EPA 2014 (Attachment 1) ETevent-res(2-6) Exposure Time (hours/event) 0.54 U.S. EPA 2014 (Attachment 1) ETevent-res(6-16) Exposure Time (hours/event) 0.71 U.S. EPA 2014 (Attachment 1) ETevent-res(16-26) Exposure Time (hours/event) 0.71 U.S. EPA 2014 (Attachment 1) EVres-c Events - child (events/day) 1 U.S. EPA 2004 Exhibit 3-2 EVres-a Events - adult (events/day) 1 U.S. EPA 2004 Exhibit 3-2 EV0-2 Events (events/day) 1 U.S. EPA 2004 Exhibit 3-2 EV2-6 Events (events/day) 1 U.S. EPA 2004 Exhibit 3-2 EV6-16 Events (events/day) 1 U.S. EPA 2004 Exhibit 3-2 EV16-26 Events (events/day) 1 U.S. EPA 2004 Exhibit 3-2 IRWres-c Ingestion Rate - Child (L/day) 0.78 U.S. EPA 2014 (Attachment 1) IRWres-a Ingestion Rate - Adult (L/day) 2.5 U.S. EPA 2014 (Attachment 1) IRW0-2 Ingestion Rate - 0-2 years (L/day) 0.78 U.S. EPA 2014 (Attachment 1) IRW2-6 Ingestion Rate - 2-6 years (L/day) 0.78 U.S. EPA 2014 (Attachment 1) IRW6-16 Ingestion Rate - 6-16 years (L/day) 2.5 U.S. EPA 2014 (Attachment 1) IRW16-26 Ingestion Rate - 16-26 years (L/day) 2.5 U.S. EPA 2014 (Attachment 1) IFWres-adj Ingestion Rate - Age-adjusted (L/kg) 327.95 Calculated using the age-adjusted intake factors equation IFWMres-adj Mutagenic Ingestion Rate - Age-adjusted (L/kg) 1,019.9 Calculated using the mutagenic age-adjusted intake factors equation SAres-c Surface area - child (cm2) 6,365 U.S. EPA 2014 (Attachment 1) SAres-a Surface area - adult (cm2) 19,652 U.S. EPA 2014 (Attachment 1) SA0-2 Surface area 0-2 years (cm2) 6,365 U.S. EPA 2014 (Attachment 1) SA2-6 Surface area 2-6 years (cm2) 6,365 U.S. EPA 2014 (Attachment 1) SA6-16 Surface area 6-16 years (cm2) 19,652 U.S. EPA 2014 (Attachment 1) SA16-26 Surface area 16-26 (cm2) 19,652 U.S. EPA 2014 (Attachment 1) DFWres-adj Dermal contact factor- age-adjusted (L/kg) 2,610,650 Calculated using the age-adjusted intake factors equation DFWMres-adj Mutagenic dermal contact factor- age-adjusted (L/kg) 8,191,633 Calculated using the mutagenic age-adjusted intake factors equation ATres Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATres-c Averaging time - child (days/year) 365 x EDres-c U.S. EPA 2014 (Attachment 1) ATres-a Averaging time - adult (days/year) 365 x EDres U.S. EPA 2014 (Attachment 1) Table 12. Indoor Worker Tapwater Land Use Equation Variables
Symbol Definition (units) Default Reference CDIiw-water-nc-ing Indoor Worker Tapwater Air Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIiw-water-nc-der Indoor Worker Tapwater Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIiw-water-nc-inh Indoor Worker Tapwater Noncarcinogenic Inhalation (mg/m3) Contaminant-specific Determined in this calculator CDIiw-water-ca-ing Indoor Worker Tapwater Air Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIiw-water-ca-der Indoor Worker Tapwater Carcinogenic Dermal (µg/m3) Contaminant-specific Determined in this calculator CDIiw-water-ca-inh Indoor Worker Tapwater Carcinogenic Inhalation (µg/m3) Contaminant-specific Determined in this calculator BWiw Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDiw Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFiw Exposure Frequency (days/year) 250 U.S. EPA 2014 (Attachment 1) ETiw Exposure Time (hours/event) 8 U.S. EPA 2014 (Attachment 1) ETevent-iw Exposure Time Shower (hours/event) 0.71 U.S. EPA 2014 (Attachment 1) EViw Events (events/day) 1 U.S. EPA 2004 Exhibit 3-2 IRWiw Ingestion Rate (L/day) 1.25 U.S. EPA 2014 (FAQ 13) SAiw Surface area (cm2) 19,652 U.S. EPA 2014 (Attachment 1) ATiw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATiw-a Averaging time (days/year) 365 x EDiw U.S. EPA 2014 (Attachment 1) Table 13. Resident Air Land Use Equation Variables
Symbol Definition (units) Default Reference CDIres-air-nc Resident Air Noncarcinogenic (mg/m3) Contaminant-specific Determined in this calculator CDIres-air-ca Resident Air Carcinogenic (µg/m3) Contaminant-specific Determined in this calculator CDIres-air-mu Resident Air Mutagenic (µg/m3) Mutagen-specific Determined in this calculator CDIres-air-ca-vc Resident Air Carcinogenic Vinyl Chloride (µg/m3) Vinyl Chloride-specific Determined in this calculator CDIres-air-tce Resident Air Carcinogenic and Mutagenic Trichloroethylene (µg/m3) Trichloroethylene-specific Determined in this calculator EDres Exposure Duration (years) 26 U.S. EPA 2014 (Attachment 1) ED0-2 Exposure Duration 0-2 years (years) 2 U.S. EPA 2014 (Attachment 1) ED2-6 Exposure Duration 2-6 years (years) 4 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration 6-16 years (years) 10 U.S. EPA 2014 (Attachment 1) ED16-26 Exposure Duration 16-26 years (years) 10 U.S. EPA 2014 (Attachment 1) EFres Exposure Frequency (days/year) 350 U.S. EPA 2014 (Attachment 1) ETres Exposure Time (hours/day) 24 The whole day ATres Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATres-a Averaging time (days/year) 365 x EDres U.S. EPA 2014 (Attachment 1) Table 14. Composite Worker Air Land Use Equation Variables
Symbol Definition (units) Default Reference CDIw-air-nc Composite Worker Air Noncarcinogenic (mg/m3) Contaminant-specific Determined in this calculator CDIw-air-ca Composite Worker Air Carcinogenic (µg/m3) Contaminant-specific Determined in this calculator EDw Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFw Exposure Frequency (days/year) 250 U.S. EPA 2014 (Attachment 1) ETw Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) ATw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATw-a Averaging time (days/year) 365 x EDw U.S. EPA 2014 (Attachment 1) Table 15. Outdoor Worker Air Land Use Equation Variables
Symbol Definition (units) Default Reference CDIow-air-nc Outdoor Worker Air Noncarcinogenic (mg/m3) Contaminant-specific Determined in this calculator CDIow-air-ca Outdoor Worker Air Carcinogenic (µg/m3) Contaminant-specific Determined in this calculator EDow Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFow Exposure Frequency (days/year) 225 U.S. EPA 2014 (Attachment 1) ETow Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) ATow Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATow-a Averaging time (days/year) 365 x EDow U.S. EPA 2014 (Attachment 1) Table 16. Indoor Worker Air Land Use Equation Variables
Symbol Definition (units) Default Reference CDIiw-air-nc Indoor Worker Air Noncarcinogenic (mg/m3) Contaminant-specific Determined in this calculator CDIiw-air-ca Indoor Worker Air Carcinogenic (µg/m3) Contaminant-specific Determined in this calculator EDiw Exposure Duration (years) 25 U.S. EPA 2014 (Attachment 1) EFiw Exposure Frequency (days/year) 250 U.S. EPA 2014 (Attachment 1) ETi Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) ATiw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATiw-a Averaging time (days/year) 365 x EDiw U.S. EPA 2014 (Attachment 1) Table 17. Construction Worker Air Land Use Equation Variables
Symbol Definition (units) Default Reference CDIcw-air-nc Construction Worker Air Noncarcinogenic (mg/m3) Contaminant-specific Determined in this calculator CDIcw-air-ca Construction Worker Air Carcinogenic (µg/m3) Contaminant-specific Determined in this calculator EDcw Exposure Duration (years) 1 U.S. EPA 2014 (Attachment 1) EWcw Exposure (weeks/year) 50 based on 50 weeks per year (reasonable work season) DWcw Exposure (days/week) 5 based on 5 days per week for 50 weeks EFcw Exposure Frequency (days/year) EW x DW based on 5 days per week for 50 weeks ETcw Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) ATcw Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATcw-a Averaging time (days/year) 365 x EDcw U.S. EPA 2014 (Attachment 1) Table 18. Excavation Worker Air Land Use Equation Variables
Symbol Definition (units) Default Reference CDIcw-air-nc Excavation Worker Air Noncarcinogenic (mg/m3) Contaminant-specific Determined in this calculator CDIcw-air-ca Excavation Worker Air Carcinogenic (µg/m3) Contaminant-specific Determined in this calculator EDew Exposure Duration (years) 1 U.S. EPA 2014 (Attachment 1) EFew Exposure Frequency (days/year) 20 based on 5 days per week for 4 weeks ETew Exposure Time (hours/day) 8 U.S. EPA 2014 (Attachment 1) ATew Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATew-a Averaging time (days/year) 365 x EDew U.S. EPA 2014 (Attachment 1) Table 19. Resident Fish Land Use Equation Variables
Symbol Definition (units) Default Reference CDIres-fsh-nc-ing Resident Fish Noncarcinogenic (mg/kg-day) Contaminant-specific Determined in this calculator CDIres-fsh-ca-ing Resident Fish Carcinogenic (mg/kg-day) Contaminant-specific Determined in this calculator CDIres-fshw-nc-ing Resident Surface Water Fish Noncarcinogenic (mg/kg-day) Contaminant-specific Determined in this calculator CDIres-fshw-ca-ing Resident Surface Water Fish Carcinogenic (mg/kg-day) Contaminant-specific Determined in this calculator BWa Body Weight (kg) 80 U.S. EPA 2014 (Attachment 1) EDfish Exposure Duration (years) 26 U.S. EPA 2014 (Attachment 1) EFfish Exposure Frequency (days/year) 350 U.S. EPA 2014 (Attachment 1) IRFa Fish Ingestion Rate (g/day) 54 U.S. EPA 2014 (Attachment 1) ATres Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATres-a Averaging time (days/year) 365 x EDres U.S. EPA 2014 (Attachment 1) Table 20. Farmer Land Use Equation Variables
Symbol Definition (units) Default Reference CDIfar-prod-nc-ing Agriculture Produce Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIfar-prod-ca-ing Agriculture Produce Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-far-prod-nc-ing Agriculture Produce Noncarcinogenic Back-calculated Concentration in Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-far-prod-ca-ing Agriculture Produce Carcinogenic Back-calculated Concentration in Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIs-far-prod-nc-ing Agriculture Produce Noncarcinogenic Back-calculated Concentration in Soil Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIs-far-prod-ca-ing Agriculture Produce Carcinogenic Back-calculated Concentration in Soil Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIsw-far-prod-nc-ing Agriculture Produce Noncarcinogenic Back-calculated Concentration in Soil and Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIsw-far-prod-ca-ing Agriculture Produce Carcinogenic Back-calculated Concentration in Soil and Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIfar-dairy-nc-ing Agriculture Dairy Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIfar-dairy-ca-ing Agriculture Dairy Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-far-dairy-nc-ing Agriculture Dairy Noncarcinogenic Back-calculated Concentration in Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-far-dairy-ca-ing Agriculture Dairy Carcinogenic Back-calculated Concentration in Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIs-far-dairy-nc-ing Agriculture Dairy Noncarcinogenic Back-calculated Concentration in Soil Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIs-far-dairy-ca-ing Agriculture Dairy Carcinogenic Back-calculated Concentration in Soil Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIsw-far-dairy-nc-ing Agriculture Dairy Noncarcinogenic Back-calculated Concentration in Soil and Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIsw-far-dairy-ca-ing Agriculture Dairy Carcinogenic Back-calculated Concentration in Soil and Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIfar-beef-nc-ing Agriculture Beef Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIfar-beef-ca-ing Agriculture Beef Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-far-beef-nc-ing Agriculture Beef Noncarcinogenic Back-calculated Concentration in Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIw-far-beef-ca-ing Agriculture Beef Carcinogenic Back-calculated Concentration in Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIs-far-beef-nc-ing Agriculture Beef Noncarcinogenic Back-calculated Concentration in Soil Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIs-far-beef-ca-ing Agriculture Beef Carcinogenic Back-calculated Concentration in Soil Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIsw-far-beef-nc-ing Agriculture Beef Noncarcinogenic Back-calculated Concentration in Soil and Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDIsw-far-beef-ca-ing Agriculture Beef Carcinogenic Back-calculated Concentration in Soil and Water Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator BWfar-a Body Weight - adult (kg) 80 U.S. EPA 2014 (Attachment 1) BWfar-c Body Weight - child (kg) 15 U.S. EPA 2014 (Attachment 1) EDfar Exposure Duration - adult (years) 40 U.S. EPA 1991a (pg. 15) EDfar-c Exposure Duration - adult (years) 6 U.S. EPA 1991a (pg. 15) EDfar-a Exposure Duration - adult (years) 34 U.S. EPA 1991a (pg. 15) EFfar Exposure Frequency (days/year) 350 U.S. EPA 2014 (Attachment 1) ATfar Averaging Time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) ATfar-c Averaging Time (days/year) 365 x EDfar-c U.S. EPA 2014 (Attachment 1) IRFfar-c Produce Ingestion Rate - Fruit - Child (mg/day) 68.1×103 U.S. EPA EPA 2011 (Table 13-5). U.S. EPA 1998 (Table C-1-2) IRFfar-a Produce Ingestion Rate - Fruit - Adult (mg/day) 176.8×103 U.S. EPA 2011 (Table 13-5). U.S. EPA 1998 (Table C-1-2) IFFfar-adj Produce Ingestion Rate - Fruit - Age-adjusted (mg/kg) 35,833,000 Calculated using the aged adjusted intake factors equation IRVfar-c Produce Ingestion Rate - Vegetables - Child (mg/day) 41.7×103 U.S. EPA EPA 2011 (Table 13-10). U.S. EPA 1998 (Table C-1-2) IRVfar-a Produce Ingestion Rate - Vegetables - Adult (mg/day) 125.7×103 U.S. EPA EPA 2011 (Table 13-10). U.S. EPA 1998 (Table C-1-2) IFVfar-adj Produce Ingestion Rate - Vegetables - Age-adjusted (mg/kg) 24,535,875 Calculated using the aged adjusted intake factors equation IRDfar-c Dairy Ingestion Rate - Child (mg/day) 349.5×103 U.S. EPA 2011 (Table 13-25). U.S. EPA 1998 (Table C-1-3) IRDfar-a Dairy Ingestion Rate - Adult (mg/day) 445.6×103 U.S. EPA 2011 (Table 13-25). U.S. EPA 1998 (Table C-1-3) IFDfar-adj Dairy Ingestion Rate - Age-adjusted (mg/kg) 115,213,000 Calculated using the aged adjusted intake factors equation IRBfar-c Beef Ingestion Rate - Child (mg/day) 40.1×103 U.S. EPA 2011 (Table 13-33). U.S. EPA 1998 (Table C-1-3) IRBfar-a Beef Ingestion Rate - Adult (mg/day) 178×103 U.S. EPA 2011 (Table 13-33). U.S. EPA 1998 (Table C-1-3) IFBfar-adj Beef Ingestion Rate - Age-adjusted (mg/kg) 30,091,500 Calculated using the aged adjusted intake factors equation Irrrup root uptake from irrigation multiplier (L/kg) contaminant-specific Calculated Irrres resuspension from irrigation multiplier (L/kg) contaminant-specific Calculated Irrdep aerial deposition from irrigation multiplier (L/kg) contaminant-specific Calculated Rupp dry root uptake for pasture multiplier (unitless) =BVdry Rupv wet root uptake for vegetables multiplier (unitless) =BVwet Qp-beef Beef Fodder Intake Rate (kg/day) 11.77 U.S. EPA 2005 (pg. B-138), U.S. EPA 1997b. Qp-dairy Dairy Fodder Intake Rate (kg/day) 20.3 U.S. EPA 2005 (pg. B-145), U.S. EPA 1997b. Qw-dairy Dairy Water Intake Rate (kg/day) 92 U.S. EPA 1999a (pg 10-23). Qw-beef Beef Water Intake Rate (kg/day) 53 U.S. EPA 1999a (pg 10-23). Qs-dairy Dairy Soil Intake Rate (kg/day) 0.4 U.S. EPA 2005 (pg. B-146), U.S. EPA 1997b. Qs-beef Beef Soil Intake Rate (kg/day) 0.5 U.S. EPA 2005 (pg. B-139), U.S. EPA 1997b. fp-beef fraction of year animal is on site (unitless) 1 Maximum value used (100%) fp-dairy fraction of year animal is on site (unitless) 1 Maximum value used (100%) fs-beef fraction of animal's food is from site (unitless) 1 Maximum value used (100%) fs-dairy fraction of animal's food is from site (unitless) 1 Maximum value used (100%) TFdairy Dairy Transfer Factor (day/kg) Contaminant-specific hierarchy selection in Section 2.4.2 TFbeef Beef Transfer Factor (day/kg) Contaminant-specific hierarchy selection in Section 2.4.2 BCF Fish Bioconcentration Factor (L/kg) Contaminant-specific CFfar-produce Fraction of Produce Consumed that is Contaminated 1 U.S. EPA 1998 CFfar-dairy Fraction of Dairy Consumed that is Contaminated 1 U.S. EPA 1998 CFfar-beef Fraction of Beef Consumed that is Contaminated 1 U.S. EPA 1998 Ir Irrigation rate (L/m2-day) 3.62 Personal communication with agricultural extension agent F irrigation period (unitless) 0.25 (based on 3 months per year) Personnal communication with agricultural extension agent λB effective rate for removal (1/day) λi+ λHL NCRP 1989 λE decay for removal on produce (1/day) λi+ (0.693/tw) NCRP 1989 λHL soil leaching rate (1/day) 0.000027 NCRP 1989 λi decay (1/day) 0.693/TR- radionuclides, 0 - non-radionuclides NCRP 1989 tW weathering half -life (day) 10 NCRP 1989 TR half-life (days) Contaminant-specific MLFpasture Pasture plant mass loading factor (unitless) 0.25 Hinton, T. G. 1992 MLFproduce Produce plant mass loading factor (unitless) 0.26 x 0.052 = 0.0135 Hinton, 1992. U.S. EPA SSG 1996 table G-1. Dry weight to wet weight conversion equation from section 4.11.9. tb long term deposition and buildup (day) 10950 NCRP 1985 tv above ground exposure time (day) 60 NCRP 1985 If interception fraction (unitless) 0.42 Miller, C. W. 1980 Yv plant yield (wet) (kg/m2) 2 NCRP 1985 P area density for root zone (kg/m2) 240 Hoffman, F. O., R. H. Gardner, and K. F. Eckerman. 1982; Peterson, H. T., Jr. 1983; McKone, T. E. 1994 T translocation factor (unitless) 1 NCRP 1984 Res Soil resuspension multiplier = MLF (produce or pasture) Hinton, T.G. 1992 Table 21. Trespasser Soil/Sediment Land Use Equation Variables
Symbol Definition (units) Default Reference CDItre-sol-ingn Trespasser Soil Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific
TeenagerDetermined in this calculator CDItre-sol-dern Trespasser Soil Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific
TeenagerDetermined in this calculator CDItre-sol-inhn Trespasser Soil Noncarcinogenic Inhalation (mg/m3) Contaminant-specific
TeenagerDetermined in this calculator CDItre-sol-ingc Trespasser Soil Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDItre-sol-derc Trespasser Soil Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDItre-sol-inhc Trespasser Soil Carcinogenic Inhalation (ug/m3) Contaminant-specific Determined in this calculator CDItre-sol-ingmu Trespasser Soil Mutagenic Ingestion (mg/kg-day) Mutagen-specific Determined in this calculator CDItre-sol-dermu Trespasser Soil Mutagenic Dermal (mg/kg-day) Mutagen-specific Determined in this calculator CDItre-sol-inhmu Trespasser Soil Mutagenic Inhalation (ug/m3) Mutagen-specific Determined in this calculator CDItre-soil-ingvc Trespasser Soil Carcinogenic Vinyl Chloride Ingestion (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDItre-soil-dervc Trespasser Soil Carcinogenic Vinyl Chloride Dermal (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDItre-soil-inhvc Trespasser Soil Carcinogenic Vinyl Chloride Inhalation (ug/m3) Vinyl Chloride-specific Determined in this calculator CDItre-soil-ingtce Trespasser Soil Carcinogenic and Mutagenic Trichloroethylene Ingestion (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDItre-soil-dertce Trespasser Soil Carcinogenic and Mutagenic Trichloroethylene Dermal (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDItre-soil-inhtce Trespasser Soil Carcinogenic and Mutagenic Trichloroethylene Inhalation (ug/m3) Trichloroethylene-specific Determined in this calculator BWtre Body Weight - trespasser (kg) 80 U.S. EPA 2014 (Attachment 1) BW6-16 Body Weight - 6-16 Years (kg) 80 U.S. EPA 2014 (Attachment 1) EDtre Exposure Duration - trespasser (years) 10 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration - 6-16 Years (years) 10 U.S. EPA 2014 (Attachment 1) EFtre Exposure Frequency - trespasser (days/year) 58 Delaware Guidance EF6-16 Exposure Frequency - 6-16 Years (days/year) 58 Delaware Guidance ETtre Exposure Time (hours/day) 3.9 Delaware Guidance ET6-16 Exposure time 6-16 Years (hours/day) 3.9 Delaware Guidance IRStre Ingestion Rate - trespasser (mg/day) 100 U.S. EPA 2014 (Attachment 1) IRS6-16 Ingestion Rate - 6-16 Years (mg/day) 100 U.S. EPA 2014 (Attachment 1) AFtre Adherence factor - trespasser (mg/cm2) 0.7 U.S. EPA 2014 (Attachment 1) AF6-16 Adherence factor 6-16 years (mg/cm2) 0.07 U.S. EPA 2014 (Attachment 1) SAtre Surface area - trespasser (cm2) 6032 U.S. EPA 2014 (Attachment 1) SA6-16 Surface area 6-16 years (cm2) 6032 U.S. EPA 2014 (Attachment 1) ATtre Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) Table 22. Trespasser Surface Water Land Use Equation Variables
Symbol Definition (units) Default Reference CDItre-wat-ingn Trespasser Surface Water Noncarcinogenic Ingestion (mg/kg-day) Contaminant-specific
TrespasserDetermined in this calculator CDItre-wat-dern Trespasser Surface Water Noncarcinogenic Dermal (mg/kg-day) Contaminant-specific
TrespasserDetermined in this calculator CDItre-wat-ingc Trespasser Surface Water Carcinogenic Ingestion (mg/kg-day) Contaminant-specific Determined in this calculator CDItre-wat-derc Trespasser Surface Water Carcinogenic Dermal (mg/kg-day) Contaminant-specific Determined in this calculator CDIrec_wat-ingmu Trespasser Surface Water Mutagenic Ingestion (mg/kg-day) Mutagen-specific Determined in this calculator CDIrec_wat-dermu Trespasser Surface Water Mutagenic Dermal (mg/kg-day) Mutagen-specific Determined in this calculator CDIrec_wat-ingvc Trespasser Surface Water Carcinogenic Vinyl Chloride Ingestion (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIrec_wat-dervc Trespasser Surface Water Carcinogenic Vinyl Chloride Dermal (mg/kg-day) Vinyl Chloride-specific Determined in this calculator CDIrec_wat-ingtce Trespasser Surface Water Carcinogenic and Mutagenic Trichloroethylene Ingestion (mg/kg-day) Trichloroethylene-specific Determined in this calculator CDIrec_wat-dertce Trespasser Surface Water Carcinogenic and Mutagenic Trichloroethylene Dermal (mg/kg-day) Trichloroethylene-specific Determined in this calculator BWtre Body Weight - trespasser (kg) 80 U.S. EPA 2014 (Attachment 1) BW6-16 Body Weight - 6-16 Years (kg) 80 U.S. EPA 2014 (Attachment 1) EDtre Exposure Duration - trespasser (years) 10 U.S. EPA 2014 (Attachment 1) ED6-16 Exposure Duration - 6-16 Years (years) 10 U.S. EPA 2014 (Attachment 1) EFtre Exposure Frequency - trespasser (days/year) 58 Delaware Guidance EF6-16 Exposure Frequency - 6-16 Years (days/year) 58 Delaware Guidance ETevent-tre Exposure Time - trespasser (hours/event) 3.9 Delaware Guidance ETevent-rec(6-16) Exposure Time (hours/event) 3.9 Delaware Guidance EVtre Events - trespasser (events/day) 1 Delaware Guidance EV6-16 Events (events/day) 1 Delaware Guidance IRWtre Ingestion Rate - trespasser (L/hour) 0.124 Table 3.5 in EFH 2011 IRW6-16 Ingestion Rate - 6-16 years (L/hour) 0.124 Time weighted average was calculated based on the upper percentile from Table 3.7 of EFH 2019 SAtre Surface area - trespasser (cm2) 19,652 U.S. EPA 2014 (Attachment 1) SA6-16 Surface area 6-16 years (cm2) 19,652 U.S. EPA 2014 (Attachment 1) ATtre Averaging time (days/year) 365 x LT U.S. EPA 2014 (Attachment 1) Table 23. Particulate Emission Factor Equation Variables
Symbol Definition (units) Default Reference PEFwind Particulate Emission Factor - Minneapolis (m3/kg) 1.36 × 109(region-specific) U.S. EPA 2002 Exhibit D-2 Q/Cwind Inverse of the Mean Concentration at the Center of a 0.5-Acre-Square Source (g/m2-s per kg/m3) 93.77 (region-specific) U.S. EPA 2002 Exhibit D-2 V Fraction of Vegetative Cover (unitless) 0.5 U.S. EPA. 2002 Equation 4-5 Um Mean Annual Wind Speed (m/s) 4.69 U.S. EPA. 2002 Equation 4-5 Ut Equivalent Threshold Value of Wind Speed at 7m (m/s) 11.32 U.S. EPA. 2002 Equation 4-5 F(x) Function Dependent on Um/Ut(unitless) 0.194 U.S. EPA. 2002 Equation 4-5 A Dispersion constant unitless PEF and region-specific U.S. EPA 2002 (pg. D-2) As Areal extent of the site or contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA 2002 (pg. D-2) B Dispersion constant unitless PEF and region-specific U.S. EPA 2002 (pg. D-2) C Dispersion constant unitless PEF and region-specific U.S. EPA 2002 (pg. D-2) Table 24. Mechanical Particulate Emission Factor Variables from Vehicle Traffic
Symbol Definition (units) Default Reference PEFsc Particulate Emission Factor - subchronic (m3/kg) Contaminant-specific U.S. EPA 2002 Equation 5-5 Q/Csr Inverse of the ratio of the 1-h geometric mean concentration to the emission flux along a straight road segment bisecting a square site (g/m2-s per kg/m3) 23.02 (for 0.5 acre site) U.S. EPA 2002 Equation 5-5 FD Dispersion correction factor (unitless) 0.185 U.S. EPA 2002 Equation 5-5 T Total time over which construction occurs (s) 7,200,000 U.S. EPA 2002 Equation 5-5 AR Surface area of contaminated road segment (m2) AR = LR x WR x 0.092903m2 /ft2) U.S. EPA. 2002 Equation 5-5 LR Length of road segment (ft) site-specific U.S. EPA. 2002 Equation 5-5 WR Width of road segment (ft)td> 20 U.S. EPA. 2002 Equation E-18 W Mean vehicle weight (tons) (number of cars x tons/car + number of trucks x tons/truck) / total vehicles) U.S. EPA. 2002 Equation 5-5 p Number of days with at least 0.01 inches of precipitation (days/year) site-specific U.S. EPA. 2002 Equation 5-5 ∑VKT Sum of fleet vehicle kilometers traveled during the exposure duration (km) ∑VKT = total vehicles x distance (km/day) x frequency (weeks/year) x (days/year) U.S. EPA 2002 Equation 5-5 A Dispersion constant unitless 12.9351 U.S. EPA 2002 Equation 5-6 As Areal extent of site surface soil contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA 2002 Equation 5-6 B Dispersion constant unitless 5.7383 U.S. EPA. 2002 Equation 5-6 C Dispersion constant unitless 71.7711 U.S. EPA 2002 Equation 5-6 tc Total time over which construction occurs (hours) 8400 U.S. EPA. 2002 Equation 5-5 Table 25. Mechanical Particulate Emission Factor Variables from other than Vehicle Traffic
Symbol Definition (units) Default Reference PEF'sc Particulate Emission Factor - subchronic (m3/kg) Contaminant-specific U.S. EPA 2002 Equation E-26 Q/Csa Inverse of the ratio of the 1-h geometric mean air concentration and the emission flux at the center of the square emission source (g/m2-s per kg/m3) site-specific U.S. EPA 2002 Equation E-15 FD Dispersion correction factor (unitless) 0.185 U.S. EPA 2002 Equation 5-5 T Total time over which construction occurs (s) 7,200,000 U.S. EPA 2002 Equation 5-5 Ac Areal extent of site surface soil contamination (acres) (range 0.5 to 500) U.S. EPA. 2002 Equation E-15 J'T (g/m2-s) Total time-averaged PM10 unit emission flux for construction activities other than traffic on unpaved roads site-specific U.S. EPA. 2002 Equation E-25 MPCwind Unit mass emitted from wind erosion (g) site-specific U.S. EPA. 2002 Equation E-20 V Fraction of Vegetative Cover (unitless) 0 U.S. EPA. 2002 Equation E-20 Um Mean Annual Wind Speed (m/s) 4.69 U.S. EPA 2002 Equation E-20 Ut Equivalent Threshold Value of Wind Speed at 7m (m/s) 11.32 U.S. EPA 2002 Equation E-20 F(x) Function Dependent on Um/Ut (unitless) 0.194 U.S. EPA 2002 Equation E-20 Asurf Areal extent of site surface soil contamination (m2/sup>) (range 0.5 to 500) U.S. EPA 2002 Equation E-20 ED Exposure duration (years) Site-specific U.S. EPA 2002 Equation E-20 Mexcav Unit mass emitted from excavation soil dumping (g) site-specific U.S. EPA 2002 Equation E-21 0.35 PM10 particle size multiplier (unitless) 0.35 U.S. EPA 2002 Equation E-21 Um Mean annual wind speed during construction (m/s) 4.69 U.S. EPA 2002 Equation E-21 Mm-excav Gravimetric soil moisture content (%) 12 (mean value for municipal landfill cover) U.S. EPA 2002 Equation E-21 ρsoil In situ soil density (includes water) (Mg/m3) 1.68 U.S. EPA 2002 Equation E-21 Aexcav Areal extent of excavation (m2) (range 0.5 to 500) U.S. EPA 2002 Equation E-21 dexcav Average depth of excavation (m) Site-specific U.S. EPA 2002 Equation E-21 NA-dump Number of times soil is dumped (unitless) 2 U.S. EPA 2002 Equation E-21 Mdoz Unit mass emitted from dozing operations (g) site-specific U.S. EPA 2002 Equation E-22 0.75 PM10 scaling factor (unitless) 0.75 U.S. EPA 2002 Equation E-22 sdoz Soil silt content (%) 6.9 U.S. EPA 2002 Equation E-22 Mm-doz Gravimetric soil moisture content (%) 7.9 (mean value for overburden) U.S. EPA 2002 Equation E-22 ∑VKTdoz Sum of dozing kilometers traveled (km) Site-specific U.S. EPA 2002 Equation E-22 Sdoz Average dozing speed (kph) 11.4 (mean value for graders) U.S. EPA 2002 Equation E-22 NA-doz Number of times site is dozed (unitless) Site-specific U.S. EPA 2002 Equation E-22 Bd Dozer blade length (m) Site-specific U.S. EPA 2002 Page E-28 Mgrade Unit mass emitted from grading operations (g) site-specific U.S. EPA 2002 Equation E-23 0.60 PM10 scaling factor (unitless) 0.60 U.S. EPA 2002 Equation E-23 ∑VKTgrade Sum of grading kilometers traveled (km) site-specific U.S. EPA 2002 Equation E-23 Sgrade Average grading speed (kph) 11.4 (mean value for graders) U.S. EPA 2002 Equation E-23 NA-grade Number of times site is graded (unitless) Site-specific U.S. EPA 2002 Equation E-23 Bg Grader blade length (m) Site-specific U.S. EPA 2002 Page E-28 Mtill Unit mass emitted from tilling operations (g) site-specific U.S. EPA 2002 Equation E-24 still Soil silt content (%) 18 U.S. EPA 2002 Equation E-24 Ac-till Areal extent of tilling (acres) Site-specific U.S. EPA 2002 Equation E-24 Ac-grade Areal extent of grading (acres) Site-specific Necessary to solve ∑VKTgrade in U.S. EPA 2002 Equation E-23 Ac-doz Areal extent of dozing (acres) Site-specific Necessary to solve ∑VKTdoz in U.S. EPA 2002 Equation E-22 NA-till Number of times soil is tilled (unitless) 2 U.S. EPA 2002 Equation E-24 A Dispersion constant unitless 2.4538 U.S. EPA 2002 Equation E-15 As Areal extent of site surface soil contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA 2002 Equation 5-6 B Dispersion constant unitless 17.5660 U.S. EPA 2002 Equation E-15 C Dispersion constant unitless 189.0426 U.S. EPA 2002 Equation E-15 tc Total time over which construction occurs (hours) 8400 U.S. EPA. 2002 Equation 5-5 Table 26. Volatilization Factor Equation Variables
Symbol Definition (units) Default Reference VFulim Unlimited Source Volatilization Factor - Minneapolis (m3/kg) Contaminant-specific U.S. EPA. 2002 Equation 4-8 Q/Cvol Inverse of the Mean Concentration at the Center of a 0.5-Acre-Square Source (g/m2-s per kg/m3) 68.81 U.S. EPA. 2002 Equation 4-8 DA Apparent Diffusivity (cm2/s) Contaminant-specific U.S. EPA. 2002 Equation 4-8 T Exposure interval (s) 819,936,000 U.S. EPA. 2002 Equation 4-8 ρb Dry soil bulk density (g/cm3) 1.5 U.S. EPA. 2002 Equation 4-8 θa Air-filled soil porosity (Lair/Lsoil) 0.28 U.S. EPA. 2002 Equation 4-8 n Total soil porosity (Lpore/Lsoil) 0.43 U.S. EPA. 2002 Equation 4-8 θw Water-filled soil porosity (Lwater/Lsoil) 0.15 U.S. EPA. 2002 Equation 4-8 ρs Soil particle density (g/cm3) 2.65 U.S. EPA. 2002 Equation 4-8 Dia Diffusivity in air (cm2/s) Contaminant-specific U.S. EPA. 2001 Diw Diffusivity in water (cm2/s) Contaminant-specific U.S. EPA. 2001 Kd Soil-water partition coefficient (Koc×foc) Contaminant-specific U.S. EPA. 2002 Equation 4-8 Koc Soil organic carbon-water partition coefficient Contaminant-specific EPI Suite foc Organic carbon content of soil (g/g) 0.006 U.S. EPA. 2002 Equation 4-8 As Areal extent of the site contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA. 2002 Equation 4-8 A Dispersion Constant 11.911 U.S. EPA 2002 Exhibit D-3 B Dispersion Constant 18.4385 U.S. EPA 2002 Exhibit D-3 C Dispersion Constant 209.7845 U.S. EPA 2002 Exhibit D-3 Table 27. Mass Limit Volatilization Factor Equation Variables
Symbol Definition (units) Default Reference VFmlim Mass Limit Volatilization Factor - Minneapolis (m3/kg) Contaminant-specific U.S. EPA. 2002 Equation 4-8 Q/Cvol Inverse of the Mean Concentration at the Center of a 0.5-Acre-Square Source (g/m2-s per kg/m3) 68.81 U.S. EPA. 2002 Equation 4-8 Ds Average Source Depth (m) site-specific U.S. EPA. 2002 Equation 4-13 T Exposure interval (years) 26 U.S. EPA. 2002 Equation 4-8 ρb Dry soil bulk density (g/cm3) 1.5 U.S. EPA. 2002 Equation 4-8 As Areal extent of the site contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA. 2002 Equation 4-8 A Dispersion Constant 11.911 U.S. EPA 2002 Exhibit D-3 B Dispersion Constant 18.4385 U.S. EPA 2002 Exhibit D-3 C Dispersion Constant 209.7845 U.S. EPA 2002 Exhibit D-3 Table 28. Subchronic Volatilization Factor Equation Variables
Symbol Definition (units) Default Reference VFulim-sc Volatilization Factor - Minneapolis (m3/kg) Contaminant-specific U.S. EPA. 2002 Equation 5-14 Q/Csa Inverse of the ratio of the 1-h geometric mean air concentration to the volatilization flux at the center of a square source (g/m2-s per kg/m3) 14.31 (for 0.5 acre site) U.S. EPA. 2002 Equation 5-14 DA Apparent Diffusivity (cm2/s) Contaminant-specific U.S. EPA. 2002 Equation 5-15 T Exposure interval (s) 30,240,000 U.S. EPA. 2002 Equation 5-17 ρb Dry soil bulk density (g/cm3) 1.5 U.S. EPA. 2002 Equation 5-14 FD Dispersion correction factor (unitless) 0.185 U.S. EPA. 2002 Equation 5-14 θa Air-filled soil porosity (Lair/Lsoil) 0.28 U.S. EPA. 2002 Equation 5-14 n Total soil porosity (Lpore/Lsoil) 0.43 U.S. EPA. 2002 Equation 5-14 θw Water-filled soil porosity (Lwater/Lsoil) 0.15 U.S. EPA. 2002 Equation 5-14 ρs Soil particle density (g/cm3) 2.65 U.S. EPA. 2002 Equation 5-14 Dia Diffusivity in air (cm2/s) Contaminant-specific U.S. EPA. 2001 Diw Diffusivity in water (cm2/s) Contaminant-specific U.S. EPA. 2001 Kd Soil-water partition coefficient (Koc×foc) Contaminant-specific U.S. EPA. 2002 Equation 4-8 Koc Soil organic carbon-water partition coefficient Contaminant-specific EPI Suite foc Organic carbon content of soil (g/g) 0.006 U.S. EPA. 2002 Equation 4-8 Ac Areal extent of the site contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA. 2002 Equation 4-8 A Dispersion Constant 2.4538 U.S. EPA 2002 Exhibit 5-15 B Dispersion Constant 17.5560 U.S. EPA 2002 Exhibit 5-15 C Dispersion Constant 189.0426 U.S. EPA 2002 Exhibit 5-15 tc Total time over which construction occurs (hours) 8400 U.S. EPA. 2002 Equation 5-5 Table 29. Subchronic Mass Limit Volatilization Factor Equation Variables
Symbol Definition (units) Default Reference VFmlim-sc Volatilization Factor - Minneapolis (m3/kg) Contaminant-specific U.S. EPA. 2002 Equation 5-14 Q/Csa Inverse of the ratio of the 1-h geometric mean air concentration to the volatilization flux at the center of a square source (g/m2-s per kg/m3) 14.31 (for 0.5 acre site) U.S. EPA. 2002 Equation 5-14 ds Average source depth (m) site-specific U.S. EPA. 2002 Equation 5-17 FD Dispersion correction factor (unitless) 0.185 U.S. EPA. 2002 Equation 5-14 T Exposure interval (s) 30,240,000 U.S. EPA. 2002 Equation 5-17 ρb Dry soil bulk density (g/cm3) 1.5 U.S. EPA. 2002 Equation 5-14 Ac Areal extent of the site contamination (acres) 0.5 (range 0.5 to 500) U.S. EPA. 2002 Equation 4-8 A Dispersion Constant 2.4538 U.S. EPA 2002 Exhibit 5-15 B Dispersion Constant 17.5560 U.S. EPA 2002 Exhibit 5-15 C Dispersion Constant 189.0426 U.S. EPA 2002 Exhibit 5-15 tc Total time over which construction occurs (hours) 8400 U.S. EPA. 2002 Equation 5-5
ANL 1993. Manual for Implementing Residual Radioactive Materials Guidelines Using RESRAD, Version 5.0. Argonne National Laboratory, Argonne, IL. ANL/EAD/LD-2
Hinton, T. G. 1992. Contamination of plants by resuspension: a review, with critique of measurement methods. Sci. Total Environ. 121:171-193.
Hoffman, F. O., R. H. Gardner, and K. F. Eckerman. 1982. Variability in dose estimates associated with the food chain transport and ingestion of selected radionuclides. NUREG/CR-2612, U. S. Nuclear Regulatory Commission.
McKone, T. E. (1994), Uncertainty and Variability in Human Exposures to Soil Contaminants Through Home-Grown Food: A Monte Carlo Assessment. Risk Analysis, 14: 449-463. DOI: 10.1111/j.1539-6924.1994.tb00263.x
Miller, C. W. (1980). An analysis of measured values for the fraction of a radioactive aerosol intercepted by vegetation. Health Phys., 38, 705-719.
NCRP 1996. Screening Models for Releases of Radionuclides to Atmosphere, Surface Water, and Ground, Vols. 1 and 2, NCRP Report No. 123. National Council on Radiation Protection and Measurements. NCRP 123
Peterson, H. T., Jr. 1983. Terrestrial and aquatic food chain pathways. pp. 5-1 to 5-156 in J. E. Till and H. R. Meyer, eds., Radiological Assessment: A Textbook on Environmental Dose Analysis. United States Nuclear Regulatory Commission, Washington, D.C.
Pinder, J. E., III, and K. W. McLeod. 1989. Mass loading of soil particles on plant surfaces. Health Physics 57:935-942.
U.S. EPA 1988. U.S. Environmental Protection Agency (U.S. EPA). Superfund Exposure Assessment Manual (SEAM). Office of Solid Waste and Emergency Response. OSWER Directive 9285.5-1. EPA/540/1-881001.
U.S. EPA 1989. U.S. Environmental Protection Agency (U.S. EPA). Risk assessment guidance for Superfund. Volume I: Human health evaluation manual (Part A). Interim Final. Office of Emergency and Remedial Response. EPA/540/1-89/002.
U.S. EPA 1991a. U.S. Environmental Protection Agency (U.S. EPA). Human health evaluation manual, supplemental guidance: "Standard default exposure factors". OSWER Directive 9285.6-03.
U.S. EPA 1991b. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation Manual (Part B, Development of Risk-Based Preliminary Remediation Goals). Office of Emergency and Remedial Response. EPA/540/R-92/003. December 1991
U.S. EPA. 1996a. Soil Screening Guidance: User's Guide. Office of Emergency and Remedial Response. Washington, DC. OSWER No. 9355.4-23.
U.S. EPA. 1996b. Soil Screening Guidance: Technical Background Document. Office of Emergency and Remedial Response. Washington, DC. OSWER No. 9355.4-17A.
U.S. EPA. 1997a. Exposure Factors Handbook. Office of Research and Development, Washington, DC. EPA/600/P-95/002Fa.
U.S. EPA. 1997b. Parameter Guidance Document. National Center for Environmental Assessment, NCEA-0238.
U.S. EPA. 1998. Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities. Office of Solid Waste, Washington, DC. Draft EPA530-D-98-001A
U.S. EPA. 1999a. Data Collection for the Hazardous Waste Identification Rule. Office of Solid Waste, Washington, DC. http://www.epa.gov/osw/hazard/wastetypes/wasteid/hwirwste/risk.htm The section on cattle fodder, soil and water intakes is here.
U.S. EPA, 2001. WATER9. Version 1.0.0. Office of Air Quality Planning and Standards, Research Triangle Park, NC. Web site at http://www.epa.gov/ttn/chief/software/water/index.html or pdf here Appendix B
U.S. EPA 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites. OSWER 9355.4-24. December 2002.
U.S. EPA 2004. Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) Final. OSWER 9285.7-02EP.July 2004.
U.S. EPA. 2005. Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities. Office of Solid Waste, Washington, DC. http://www.epa.gov/osw/hazard/tsd/td/combust/risk.htm. The pdf is available here Final EPA530-D-98-001A.
U.S. EPA. 2011. Exposure Factors Handbook. Office of Research and Development, Washington, DC. EPA/600/R-090/052F
U.S. EPA. 2014. OSWER Directive 9200.1-120 and FAQ. Office of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 2018. Region 4 Human Health Risk Assessment Supplemental Guidance. EPA Region 4. March, 2018.
U.S. EPA. 2019. Exposure Factors Handbook Chapter 3 Updates. Office of Research and Development, Washington, DC. EPA/600/R-090/052F
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