Uncover the power of Regional Screening Levels with this comprehensive Users Guide. This guide provides crucial insights into protecting human health at CERCLA sites from CONDUCT.EDU.VN. Learn how to effectively utilize risk assessment, understand exposure pathways, and apply toxicity values for informed decision-making.
1. Introduction to Regional Screening Levels (RSLs)
The Regional Screening Levels (RSLs) website, hosted by CONDUCT.EDU.VN, provides essential tools for Remedial Project Managers (RPMs), On-Scene Coordinators (OSCs), and risk assessors involved in hazardous waste site decision-making under CERCLA. This “users guide” is designed to help professionals and others determine if the concentration levels of contaminants found at a specific site warrant further investigation. It is important to understand that these screening tables and calculator results are to be used at one’s discretion, ensuring assumptions are well understood and appropriately applied, considering ecological risks and adhering to ethical guidelines.
RSLs are chemical-specific concentrations in air, drinking water, and soil that, when exceeded, suggest the need for further investigation. These levels are typically used early in the Remedial Investigation (RI) process to select appropriate detection limits for RI sampling. It is crucial to emphasize that RSLs are not cleanup standards but rather screening tools used to guide the initial stages of site assessment. To expand your knowledge of acceptable conduct, CONDUCT.EDU.VN provides additional resources and tools.
2. Understanding the RSL Website on CONDUCT.EDU.VN
Navigating the RSL website on CONDUCT.EDU.VN effectively requires an understanding of several key elements. This includes general considerations, exposure assumptions, toxicity values, chemical-specific parameters, Maximum Contaminant Levels (MCLs), and how risk is presented on the website.
2.1 General Considerations
Risk-based Screening Levels (SLs) are derived from equations that combine exposure assumptions with chemical-specific toxicity values. These equations help determine the potential risk to human health from exposure to contaminants. The reliability of these SLs depends on the accuracy and relevance of the data used.
2.2 Exposure Assumptions
Generic Screening Levels (SLs) are based on default exposure parameters and factors that represent Reasonable Maximum Exposure (RME) conditions for long-term, chronic exposures. These assumptions are based on EPA’s Risk Assessment Guidance for Superfund, Part B Manual and Soil Screening Guidance documents. Site-specific information may warrant modifying the default parameters in the equations to calculate site-specific SLs. It is important to document clearly the equations and exposure parameters used in deriving SLs at a site, including a discussion of the assumptions made.
2.3 Toxicity Values
In 2003, EPA’s Superfund program revised its hierarchy of human health toxicity values, establishing three tiers of toxicity values. The toxicity values used as defaults in these tables and calculator are consistent with the 2003 guidance. Users wishing to consider using other toxicity values should carefully review the basis for the value and document the basis of toxicity values used on a CERCLA site. CONDUCT.EDU.VN encourages users to seek support from a Superfund risk assessor for chemicals that lack toxicity values in the sources outlined above.
2.3.1 Reference Doses
Reference Doses (RfDs) are estimates of daily oral exposure to the human population, including sensitive subgroups, that are likely to be without an appreciable risk of deleterious effects during a lifetime. Chronic oral RfDs are used to evaluate potential noncarcinogenic effects associated with exposure periods greater than 7 years, while subchronic oral RfDs are developed to be protective for short-term exposure to a compound.
2.3.2 Reference Concentrations
Reference Concentrations (RfCs) are estimates of continuous inhalation exposure to the human population that are likely to be without an appreciable risk of deleterious effects during a lifetime. Chronic inhalation RfCs are used for continuous exposures that occur for 7 years or more, while subchronic inhalation RfCs are used for exposures between 2 weeks and 7 years.
2.3.3 Slope Factors
Slope Factors are toxicity data used to evaluate potential human carcinogenic risks. They are plausible upper-bound estimates of the probability of a response per unit intake of a chemical over a lifetime. Oral slope factors are used to evaluate the probability of an individual developing cancer from oral exposure to contaminant levels over a lifetime.
2.3.4 Inhalation Unit Risk
The Inhalation Unit Risk (IUR) is the upper-bound excess lifetime cancer risk estimated to result from continuous exposure to an agent at a concentration of 1 µg/m3 in air.
2.3.5 Toxicity Equivalence Factors (TEF)
Toxicity Equivalence Factors (TEFs) are applied to the measured concentrations in environmental media to create a toxicity equivalent concentration for chemicals that are members of the same family and exhibit similar toxicological properties. These factors are particularly useful for dioxins, furans, and dioxin-like PCBs.
| CASRN | Dioxins and Furans | TEF |
|---|---|---|
| 1746-01-6 | 2,3,7,8-TCDD | 1 |
| 40321-76-4 | 1,2,3,7,8-PeCDD | 1 |
| 39227-28-6 | 1,2,3,4,7,8-HxCDD | 0.1 |
| 57653-85-7 | 1,2,3,6,7,8-HxCDD | 0.1 |
| 19408-74-3 | 1,2,3,7,8,9-HxCDD | 0.1 |
| 35822-46-9 | 1,2,3,4,6,7,8-HpCDD | 0.01 |
| 3268-87-9 | OCDD | 0.0003 |
| 51207-31-9 | 2,3,7,8-TCDF | 0.1 |
| 57117-41-6 | 1,2,3,7,8-PeCDF | 0.03 |
| 57117-31-4 | 2,3,4,7,8-PeCDF | 0.3 |
| 70648-26-9 | 1,2,3,4,7,8-HxCDF | 0.1 |
| 57117-44-9 | 1,2,3,6,7,8-HxCDF | 0.1 |
| 72918-21-9 | 1,2,3,7,8,9-HxCDF | 0.1 |
| 60851-34-5 | 2,3,4,6,7,8-HxCDF | 0.1 |
| 67562-39-4 | 1,2,3,4,6,7,8-HpCDF | 0.01 |
| 55673-89-7 | 1,2,3,4,7,8,9-HpCDF | 0.01 |
| 39001-02-0 | OCDF | 0.0003 |
2.3.6 Relative Potency Factors (RPF)
Relative Potency Factors (RPFs) are used to adjust the oral slope factor or inhalation unit risk based on the relative potency to the primary compound for chemicals that are members of the same family and exhibit similar toxicological properties. These factors are commonly used for polycyclic aromatic hydrocarbons (PAHs).
| CASRN | Compound | RPF |
|---|---|---|
| 50-32-8 | Benzo(a)pyrene | 1.0 |
| 56-55-3 | Benz(a)anthracene | 0.1 |
| 205-99-2 | Benzo(b)fluoranthene | 0.1 |
| 207-08-9 | Benzo(k)fluoranthene | 0.01 |
| 218-01-9 | Chrysene | 0.001 |
| 53-70-3 | Dibenz(a,h)anthracene | 1.0 |
| 193-39-5 | Indeno(1,2,3-c,d)pyrene | 0.1 |
2.4 Chemical-specific Parameters
Several chemical-specific parameters are needed for the development of RSLs, including the organic carbon partition coefficient (Koc), dermal permeability coefficient (Kp), molecular weight (MW), water solubility (S), Henry’s Law Constant (H’), diffusivity in air (Dia), diffusivity in water (Diw), fish bioconcentration factor (BCF), soil-water partition coefficient (Kd), and vapor pressure (VP).
2.5 Maximum Contaminant Levels (MCLs)
Maximum Contaminant Levels (MCLs) are enforceable standards set by the EPA for contaminants in drinking water to protect public health. MCLs are provided in the RSL tables and calculator output for users’ information. RSLs are generated by and for the Superfund program, while MCLs are generated by the Office of Water. If you have questions about the use of MCLs and/or RSLs at a Superfund site, consult your regional risk assessor or contact CONDUCT.EDU.VN for ethical and factual support.
2.6 Understanding Risk Output on the RSL Website
The RSL calculator provides an option to select risk output. Selecting risk output requires the calculator to be run in “Site-Specific” mode. This portion of the risk assessment process is generally referred to as “Risk Characterization.”
2.6.1 How Risk is Calculated
Risk (carcinogenic risk and hazard quotient) is calculated using a simple method that relies on the linear nature of the relationship between concentration and risk. The equations are:
- Carcinogenic: Risk = (C × TR) / RSL
- Noncarcinogenic: HQ = (C × THQ) / RSL
where:
- Risk = a unitless probability of an individual developing cancer over a lifetime
- HQ = unitless ratio of exposure concentration to reference concentration
- C = Concentration entered by the user in site-specific mode
- TR = Target Risk provided by the user in site-specific mode
- THQ = Target Hazard Quotient provided by the user in site-specific mode
- RSL = Regional Screening Level, determined by the values entered by the user in site-specific mode
2.6.2 One-Hit Rule for Carcinogenic Risk
The linear risk equation is 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, such as the one-hit equation.
3. Understanding Your Superfund Site
The Generic Tables on conduct.edu.vn provide generic concentrations in the absence of site-specific exposure assessments. These concentrations can be used for prioritizing multiple sites, setting risk-based detection limits, focusing future site investigation and risk assessment efforts, identifying contamination which may warrant cleanup, identifying sites that warrant no further action, and establishing initial cleanup goals when site-specific data are lacking. Use of the noncancer RSLs based on a target Hazard Quotient of 0.1 is recommended for initial screening of sites where more than one chemical with the same toxic endpoint might be present.
Tables are provided in either MS Excel or PDF format, including:
- Summary Table
- Residential Soil Supporting Table
- Industrial Soil Supporting Table
- Residential Air Supporting Table
- Industrial Air Supporting Table
- Residential Tapwater Supporting Table
3.1 Developing a Conceptual Site Model
When using generic SLs at a site, the exposure pathways of concern and site conditions should match those used in developing the SLs. It is necessary to develop a conceptual site model (CSM) to identify likely contaminant source areas, exposure pathways, and potential receptors. The final CSM diagram represents linkages among contaminant sources, release mechanisms, exposure pathways, routes, and receptors based on historical information.
3.2 Background
EPA may be concerned with two types of background at sites: naturally occurring and anthropogenic. Generally, EPA does not clean up below natural background. Background levels should be addressed as they are for other contaminants at CERCLA sites.
3.3 Potential Problems
Potential misapplication can occur with any risk-based screening table or tool. To prevent misuse of the SLs, avoid applying SLs without adequately developing a conceptual site model, not considering the effects from the presence of multiple contaminants, using the SLs as cleanup levels without adequate consideration of the other NCP remedy selection criteria, using outdated SLs, not considering the effects of additivity when screening multiple chemicals, applying inappropriate target risks, not performing additional screening for pathways not included in these SLs, and adjusting SLs upward without consulting a toxicologist or regional risk assessor.
4. Land Use Descriptions, Equations, and Technical Documentation
The SLs consider human exposure to individual contaminants in air, drinking water, and soil. The equations and technical discussion are aimed at developing risk-based SLs or PRGs. The following text presents the land use equations and their exposure routes.
4.1 Resident
This receptor spends most, if not all, of the day at home and is assumed to be exposed to contaminants via incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and fugitive dust.
4.1.1 Resident Soil
This equation is for developing residential default screening levels that are presented in the RSL Generic Tables.
- Noncarcinogenic – Child: Contains incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and particulates emitted from soil.
- Noncarcinogenic – Adult: Contains incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and particulates emitted from soil.
- Carcinogenic: Contains incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and particulates emitted from soil.
- Mutagenic: Contains incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and particulates emitted from soil.
- Vinyl Chloride – Carcinogenic: Contains incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and particulates emitted from soil.
- Trichloroethylene – Carcinogenic and Mutagenic: Contains incidental ingestion of soil, dermal contact with soil, and inhalation of volatiles and particulates emitted from soil.
4.1.2 Resident Tapwater
This receptor is exposed to chemicals in water that are delivered into a residence. Ingestion of drinking water is an appropriate pathway for all chemicals, while inhalation exposure is only calculated for volatile compounds.
- Noncarcinogenic – Child: Contains ingestion of water, dermal exposure, and inhalation of volatiles.
- Noncarcinogenic – Adult: Contains ingestion of water, dermal exposure, and inhalation of volatiles.
- Carcinogenic: Contains ingestion of water, dermal exposure, and inhalation of volatiles.
- Mutagenic: Contains ingestion of water, dermal exposure, and inhalation of volatiles.
- Vinyl Chloride – Carcinogenic: Contains ingestion of water, dermal exposure, and inhalation of volatiles.
- Trichloroethylene – Carcinogenic and Mutagenic: Contains ingestion of water, dermal exposure, and inhalation of volatiles.
4.1.3 Resident Air
This receptor spends most of the day at home and is assumed to be exposed to contaminants via inhalation of ambient air.
- Noncarcinogenic: Inhalation
- Carcinogenic: Inhalation
- Mutagenic: Inhalation
- Vinyl Chloride – Carcinogenic: Inhalation
- Trichloroethylene – Carcinogenic and Mutagenic: Inhalation
4.2 Composite Worker
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.
4.2.1 Composite Worker Soil
This land use is for developing industrial default screening levels that are presented in the RSL Generic Tables.
- Noncarcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
- Carcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
4.2.2 Composite Worker Air
This land use is for developing industrial default screening levels that are presented in the RSL Generic Tables.
- Noncarcinogenic: Inhalation
- Carcinogenic: Inhalation
4.3 Outdoor Worker
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.
4.3.1 Outdoor Worker Soil
The outdoor worker soil land use is not provided in the RSL Generic Tables, but RSLs can be created by using the Calculator.
- Noncarcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
- Carcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
4.3.2 Outdoor Worker Air
The outdoor worker air land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
- Noncarcinogenic: Inhalation
- Carcinogenic: Inhalation
4.4 Indoor Worker
This receptor spends most, if not all, of the workday indoors.
4.4.1 Indoor Worker Soil
The indoor worker soil land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
- Noncarcinogenic: Contains incidental ingestion of soil and inhalation of volatiles and particulates emitted from soil.
- Carcinogenic: Contains incidental ingestion of soil and inhalation of volatiles and particulates emitted from soil.
4.4.2 Indoor Worker Air
The indoor worker air land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
- Noncarcinogenic: Inhalation
- Carcinogenic: Inhalation
4.5 Construction Worker
The construction worker soil land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
4.5.1 Construction Worker Soil Exposure to Standard Vehicle Traffic
This is a short-term receptor exposed during the work day working around vehicles suspending dust in the air.
- Noncarcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
- Carcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
4.5.2 Construction Worker Soil Exposure to Other Construction Activities
This is a short-term receptor exposed during the work day working around heavy vehicles suspending dust in the air.
- Noncarcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
- Carcinogenic: Contains incidental ingestion of soil, dermal exposure, and inhalation of volatiles and particulates emitted from soil.
4.6 Recreator
The recreator soil land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
4.6.1 Recreator Soil or Sediment
This receptor spends time outside involved in recreational activities.
- Noncarcinogenic – Child: Contains incidental ingestion of soil or sediment, dermal contact with soil or sediment, and inhalation of volatiles and particulates emitted from soil or sediment.
- Noncarcinogenic – Adult: Contains incidental ingestion of soil or sediment, dermal contact with soil or sediment, and inhalation of volatiles and particulates emitted from soil or sediment.
- Carcinogenic: Contains incidental ingestion of soil or sediment, dermal contact with soil or sediment, and inhalation of volatiles and particulates emitted from soil or sediment.
- Mutagenic: Contains incidental ingestion of soil or sediment, dermal contact with soil or sediment, and inhalation of volatiles and particulates emitted from soil or sediment.
- Vinyl Chloride – Carcinogenic: Contains incidental ingestion of soil or sediment, dermal contact with soil or sediment, and inhalation of volatiles and particulates emitted from soil or sediment.
- Trichloroethylene – Carcinogenic and Mutagenic: Contains incidental ingestion of soil or sediment, dermal contact with soil or sediment, and inhalation of volatiles and particulates emitted from soil or sediment.
4.6.2 Recreator Surface Water
The recreator surface water land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
- Noncarcinogenic – Child: Contains incidental ingestion of water and dermal exposure.
- Noncarcinogenic – Adult: Contains incidental ingestion of water and dermal exposure.
- Carcinogenic: Contains incidental ingestion of water and dermal exposure.
- Mutagenic: Contains incidental ingestion of water and dermal exposure.
- Vinyl Chloride – Carcinogenic: Contains incidental ingestion of water and dermal exposure.
- Trichloroethylene – Carcinogenic and Mutagenic: Contains incidental ingestion of water and dermal exposure.
4.7 Ingestion of Fish
The ingestion of fish land use is not provided in the Generic Tables, but RSLs can be created by using the Calculator.
4.7.1 Noncarcinogenic
Contains consumption of fish.
4.7.2 Carcinogenic
Contains consumption of fish.
4.8 Soil to Groundwater
This land use is for developing residential default soil screening levels for the protection of groundwater that are presented in the RSL Generic Tables.
4.8.1 Noncarcinogenic Tapwater Equations for SSLs
The tapwater equations are used to calculate the noncarcinogenic SSLs for volatiles and nonvolatiles.
4.8.2 Carcinogenic Tapwater Equations for SSLs
The tapwater equations are used to calculate the carcinogenic SSLs for volatiles and nonvolatiles.
4.8.3 Method 1 for SSL Determination
Method 1 employs a partitioning equation for migration to groundwater, and defaults are provided.
4.8.4 Method 2 for SSL Determination
Method 2 employs a mass-limit equation for migration to groundwater, and site-specific information is required.
4.8.5 Determination of the Dilution Factor
The SSL values in the download tables are based on a dilution factor of 1.
4.8.6 Conservative and Simplifying Assumptions for the Soil to Groundwater Scenario
These assumptions include:
- The source is infinite.
- Contaminants are uniformly distributed throughout the zone of contamination.
- Soil contamination extends from the surface to the water table.
- There is no contaminant loss due to biological degradation or volatilization.
- Equilibrium soil/water partitioning is instantaneous and linear.
- The receptor well is at the edge of the source and is screened within the plume.
- The aquifer is unconsolidated and unconfined.
- Aquifer properties are homogeneous and isotropic.
- Chelating or complexing agents not present.
- No facilitated transport of inorganic contaminants in the aquifer.
4.9 Supporting Equations and Parameter Discussion
4.9.1 Wind-driven Particulate Emission Factor (PEF)
Inhalation of contaminants adsorbed to respirable particles (PM10) was assessed using a default PEF equal to 1.36 x 109 m3/kg.
4.9.2 Vehicle traffic-driven Particulate Emission Factor (PEFsc)
The equation to calculate the subchronic particulate emission factor (PEFsc) focuses exclusively on emissions from truck traffic on unpaved roads.
4.9.3 Other than vehicle traffic-driven Particulate Emission Factor (PEF’sc)
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.
4.9.4 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.
4.9.5 Mass-limit Chronic Volatilization Factor (VFmlim)
This Equation presents a model for calculating mass-limit SSLs for the outdoor inhalation of volatiles.
4.9.6 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 (VFulim-sc) that relates the concentration of a contaminant in soil to the concentration in air resulting from volatilization.
4.9.7 Mass-limit Subchronic Volatilization Factor for Construction Worker (VFmlim-sc)
Because 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.
4.9.8 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.
4.9.9 Henry’s Law constant and Vapor Pressure Determination at Temperature Other Than 25°C
In site-specific mode for soil and soil to groundwater land uses, users are given the option to the change groundwater-soil system temperature from the default of 25°C to a site-specific value.
5. Special Considerations
Most of the SLs 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 SLs are recommended.
5.1 Cadmium
“Cadmium (Diet)” is for food and soil use; “Cadmium (Water)” is for water use only. The RSLs use the chronic MRL from ATSDR as the Cadmium RfD instead of the IRIS value.
5.2 Lead
EPA has no consensus RfD or SFO for inorganic lead, so it is not possible to calculate SLs using the same methodology used for other chemicals. EPA evaluates lead exposure in residential scenarios by using models such as the Integrated Exposure-Uptake Biokinetic Model (IEUBK) to estimate a blood-lead concentration.
5.3 Manganese
The IRIS RfD includes manganese from all sources, including diet.
5.4 Vanadium Compounds
The oral RfD toxicity value for Vanadium is derived from the IRIS oral RfD for Vanadium Pentoxide by factoring out the molecular weight of the oxide ion.
5.5 Uranium
The “Uranium Soluble Salts” RSL uses the ATSDR intermediate MRL instead of the IRIS oral RfD.
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 be present.
5.7 Aminodinitrotoluenes
The IRIS oral RfD for 2,4-Dinitrotoluene is no longer used as a surrogate for 2-Amino-4,6-Dinitrotoluene and 4-Amino-2,6-Dinitrotoluene.
5.8 PCBs and Aroclors
In the RSL Tables, the chemical group, “Polychlorinated Biphenyls (PCBs),” has three distinct types of PCBs listed: Aroclors, individual PCB congeners, and risk/persistence-based PCBs.
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.
5.10 Arsenic
Arsenic screening levels for ingestion of soil and sediment are now calculated with the default relative bioavailability factor (RBA) of 0.6.
5.11 Total Petroleum Hydrocarbons (TPHs)
Within the Superfund program, when TPHs are considered in the site characterization, they are assessed in supplemental health risk assessments only for potential noncancer health effects.
5.12 Soil Saturation Limit (Csat)
The soil saturation concentration, Csat, corresponds to the contaminant concentration in soil at which the absorptive limits of the soil particles, the solubility limits of the soil pore water, and saturation of soil pore air have been reached.
5.13 SL Theoretical Ceiling Limit
The ceiling limit of 10+5 mg/kg is equivalent to a chemical representing 10% by weight of the soil sample.
5.14 Target Risk
With the exceptions described previously, SLs are chemical concentrations that correspond to fixed levels of risk (i.e., either a one-in-one million [10-6] for cancer risk or a noncarcinogenic hazard quotient of 1) in soil, air, and water.
5.15 Screening Sites with Multiple Contaminants
Users needing to screen sites with multiple contaminants should consult with their regional risk assessors.
5.16 Deriving Soil Gas SLs
The air SLs could apply to indoor air from, e.g., a vapor intrusion scenario. To model indoor air concentrations from other media (e.g., soil gas, groundwater), consult with regional experts in vapor intrusion.
5.17 Mutagens
Some of the carcinogens in this tool operate by a mutagenic mode of action for carcinogenesis.
| 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* |
| Chloroprene | 126-99-8 | IRIS |
| Chromium(VI) | 18540-29-9 | 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 |
| Dimethylbenzidine, 3,3′ | 119-93-7 | PPRTV |
| Dimethoxybenzidine, 3,3′- | 119-90-4 | PPRTV |
| Ethylene Oxide | 75-21-8 | IRIS |
| Formaldehyde | 50-00-0 | 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](https://iris.epa.gov/Document/&deid=3 |
