History of changes to CLARC

The Cleanup Levels and Risk Calculation (CLARC) is an Excel spreadsheet and other technical resources that help contamination cleanup professionals establish cleanup levels at a contaminated site. This page outlines the most significant changes to CLARC from 2004 through today.

Many of the terms and abbreviations mentioned here are defined in the glossary.

2024 | 2023 | 2022 | 20212020 | 2019 and earlier


February 2024

  1. Updated toxicity values for the following hazardous substances based on a review of EPA's November 2023 Regional Screening Level table:

    • Oral RfD: Acrylonitrile lost its ATSDR chronic RfD (the Tox Profile is now DRAFT). The ATSDR value has been replaced with the chronic oral RfD provided in EPA's HEAST.
    • Inhalation RfC/RfDi: Nickel lost its ATSDR chronic RfC (the Tox Profile is now DRAFT). The ATSDR value has been replaced with the chronic RfC provided by Cal EPA.

    There were no updates to the oral CFP or the inhalation IUR/CPFi.

  2. Added noncancer effects information for acrylonitrile, n-hexane, and nickel.

  3. Updated chemical-specific values according to a January 2024 review of the Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (RAIS) chemical database:

    • Added molecular weight as a chemical-specific value in CLARC. This parameter may be used to evaluate fate and transport and is included in the four-phase partitioning leaching model.
    • Updated solubility for PFNA (a PFAS compound).
    • Updated vapor pressure for HFPO-DA GenX (a PFAS compound).
    • Updated Kd and Koc for HFPO-DA GenX.

  4. Added Chemical Data Subgroup column. This breaks down the data groups into sub-categories that better align with categories identified in Ecology's Cleanup and Tank Search database (e.g., halogenated vs. non-halogenated chemicals). Note: chemicals used as solvents have been identified as "Solvent". This classification is also included in Cleanup and Tank Search. However, there may be other chemicals in CLARC that have been used as a solvent in some capacity but that are not specifically identified as "Solvent".


2024 | 2023 | 2022 | 20212020 | 2019 and earlier

August 2023

  1. Added Cyclohexene and Perfluorohexanoic Acid (PFHxA) to CLARC. Cyclohexene is used as a toxicity surrogate for the low aliphatic range (EC > 5 to EC 8) when deriving site-specific TPH levels under Method B or C. We added PFHxA (a PFAS compound) based on available toxicity data from EPA IRIS. Note: We incorporated toxicity information for cyclohexene into our Toxicity Data and Physical/Chemical Properties for Petroleum Mixtures guidance. The information is also in a new Excel Workbook tool (MTCATPH Ver. 12.0) for calculating cleanup levels for petroleum contaminated sites.

  2. Updated toxicity values for the following hazardous substances based on a review of EPA’s May 2023 Regional Screening Level table.

    • Oral RfD: Bromoacetic acid and dibromoacetic acid have new chronic oral RfDs from Cal EPA. Phosphoric acid has a new PPRTV chronic oral RfD (see  PPRTV Sodium and Potassium Salts of Inorganic Phosphates, EPA/690/R-23/001F, Nov. 2022). Alpha Hexachlorocyclohexane lost its ATSDR chronic oral RfD.
    • Inhalation RfC/RfDi: Calcium cyanide, potassium cyanide, and sodium cyanide have new chronic RfCs from Cal EPA. Isobutyl alcohol has a new PPRTV chronic RfC.
    • Oral CPF: Dibromoacetic acid has a new oral CPF from Cal EPA.
    • Inhalation IUR/CPFi: Bromate and 3,3'-dimethoxybenzidine have new inhalation URFs from Cal EPA.

  3. Updated chemical-specific values based on a June 2023 review of the Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (RAIS) chemical database.

    • Henry’s law: The Henry’s law dimensionless value at 25° C for mercury was updated to 0.47 (unitless) based on WAC 173-340-747(4)(d). Updates were also made to nonylphenol, PFOS, and white mineral oil based on data in ORNL. Data from ORNL RAIS (i.e., boiling point, critical temperature, enthalpy of vaporization) were reviewed to adjust Henry’s law based on 25° Celsius to 13° Celsius. We updated 18 compounds. Formulas in EPA’s Vapor Intrusion Screening Level (VISL) excel spreadsheet system (Chem Props worksheet) were used to make the adjustment.
    • Solubility for chlorine dioxide, PFHxS (a PFAS compound), and white mineral oil.
    • Vapor pressure for phosphoric acid and thallium carbonate.
    • Kd for nickel refinery dust.
    • Koc updated for white mineral oil.
    • INH groundwater factors for sodium azide and thallium carbonate to reflect that these are not volatile.
    • GI and ABS (dermal parameters) for DDT to reflect that it’s not a volatile compound.

  4. Updates to surface water ARARs:

    • Added a note to the 173-201A-240 Marine Acute and Chronic Aquatic Life Criteria for cyanide. The note reflects that cyanide has both a state-wide criterion and a criterion specific to Puget Sound waters.
    • Removed the freshwater and marine aquatic life CWA §304 criteria for methyl mercury. These criteria apply to total mercury, and were derived from data for inorganic mercury (II). We added a note to the cells that correspond to the marine surface water human health criteria. These criteria are not in units of µg/L but in mg/kg fish tissue. There are no longer soil leaching cleanup levels for the protection of surface water for methyl mercury due to the absence of target surface water criteria.

  5. Removed soil cleanup levels protective of the groundwater discharge to surface water pathway for individual cPAHs, other than benzo(a)pyrene (BaP). For evaluating sites where groundwater discharges to surface water, compliance with cPAHs in soil for the soil leaching pathway is based on the total cPAH mixture and achieving the cleanup level for BaP (WAC 173-340-708(8)(e)(iv)). See Ecology Implementation Memorandum #10 — Evaluating the Human Health Toxicity of Carcinogenic PAHs (cPAHs) Using Toxicity Equivalency Factors (TEFs) — for guidance on evaluating the potential for cPAH mixtures in soil to impact groundwater.

  6. Changed the hexachloroethane VI groundwater screening levels in the Vapor Intrusion Tables because data is no longer available to calculate a Henry's law at 13° C. The screening level is now based on a Henry's law at 25° C.

  7. Re-named the "Sub-Slab Soil Gas Screening Level" to “Soil Gas Screening Level” because there is no longer a distinction between shallow and deep soil gas screening levels.

  8. Added DDD, DDE, and perfluorohexanoic acid (PFHxA) to the noncancer effects table.

January 2023

  1. Added perfluorobutanoic scid (PFBA) based on available toxicity data from EPA IRIS.

  2. Deleted two hazardous substances from CLARC:

    • Dibenzothiophene: There is no longer toxicity data for this chemical as EPA dropped the chronic PPRTV screening level oral RfD.
    • 1,2-Dichloroethylene (mixed isomers): Toxicity data for 1,2-dichloroethylene (mixed isomers) is from the 1997 HEAST database and is based on the toxicity for 1,1-dichloroethylene (by analogy). EPA IRIS has toxicity data for both cis and trans 1,2-dichloroethylene and these are provided in CLARC.

  3. Updated toxicity values for the following hazardous substances based on a review of EPA's November 2022 Regional Screening Level table:

    • Oral RfD: DDD and DDE have new oral RfDs from ATSDR.
    • Inhalation RfC/RfDi: cis-1,2-dichloroethylene has a chronic PPRTV screening level RfC from EPA. The RfC for glycidaldehyde remains the same but the toxicity source has been updated to a screening level PPRTV value.

    There were no updates to the oral CPF or inhalation IUR/CPFi.

  4. Added cis-1,2-dichloroethylene  to the VI tables based on its new inhalation RfC toxicity value.

  5. Added additional chemicals with toxicity data from EPA's IRIS database to the noncancer effects table along with PFAS chemicals and several phthalates. The noncancer critical effect for 1,2,4-trimethylbenzene was updated/corrected for the inhalation route.

  6. Added a note for white mineral oil (CAS 8012-95-1) to explain why we removed the Method B and C soil and groundwater levels from CLARC.

  7. Added to the note for Chromium VI. We added information about the derivation of the inhalation unit risk (IUR) of 8.4E-02 (µg/m3)-1 (assuming 100% Cr VI).

  8. Removed the term "low organic" from the 2,3,7,8-TCDD chemical name. Low organic corresponds to low organic soils. However, the Method A and B soil levels for 2,3,7,8-TCDD provided in CLARC apply to all soil types, so the term "low organic" is not needed.

  9. Rescinded TCP's Interim Policy 730. In January 2021, we published the Toxics Cleanup Program's Interim Policy 730 (Taking into Account Federal Human Health Surface Water Quality Criteria under MTCA) to address EPA’s withdrawal of surface water quality criteria from regulation 40 CFR 131.45. EPA signed a rule on Nov.14, 2022 to restore the withdrawn values to the regulation. The final rule was published in the Federal Register (Vol. 87, No. 222) on Friday, Nov. 18, 2022, and became effective on Dec. 19, 2022. As a result, we have rescinded Policy 730 and restored all of the 40 CFR 131.45 values in CLARC  to EPA's regulation. All of the surface water criteria under 40 CFR 131.45 provided in CLARC are applicable federal standards.

    Note: We've removed 40 CFR 131.45 values for 2,3,7,8-TCDD and thallium. These were the values that EPA had originally promulgated under the National Toxics Rule (40 CFR 131.36). EPA’s final rule does not change or supersede Washington’s WAC 173-201A human health values for 2,3,7,8-TCDD and thallium that EPA approved in 2019. EPA had previously taken no action on these two chemicals in 2016.

  10. Issued new Guidance on the Use of Method A, B, and C Cleanup Levels and Mixing Methods.

  11. Removed CLARC's individual PDF files from the webpage. CLARC's "Master PDF" file contains the entirety of CLARC's data tables and information, bookmarked for easy navigation. We're no longer posting individual PDFs of each media table.


2024 | 2023 | 2022 | 2021 | 2020 | 2019 and earlier

July 2022


  1. Modified the dermal exposure parameters described in Note 8 of the July 2022 CLARC updates. For those chemicals that lack chemical-specific ABS and GI dermal exposure values, we no longer apply the defaults recommended in EPA's RAGS Part E, and have reverted back to the MTCA default ABS and GI values provided in WAC 173-340-740(3)(c)(iii). We have retained the chemical-specific values from EPA's RAGS Part E. We've also added chemical-specific values from the ATSDR toxicological profiles for benzene, toleuene, ethylbenzene, and xylenes. On a site-specific basis the default recommendations provided in RAGS Part E may still be considered under the allowable modifications provided in MTCA's Modified Method B and C soil cleanup levels (see WAC 173-340-740 (3)c(c)(ii)(C)WAC 173-340-745(5(c)(ii)(C)).

  2. Updated petroleum guidance. Consistent with the note above on dermal exposure parameters, we've updated the ABS and GI dermal exposure parameters in two other resources:

  3. ARAR update for nickel. The drinking water MCL for nickel under Chapter 246-290 WAC has been withdrawn. There is no federal or Washington State MCL for nickel.

  4. Deleted Acetone from the vapor intrusion tables because it no longer has inhalation toxicity criteria (the ATSDR chronic inhalation reference concentration has been withdrawn).

  5. Corrected the Vapor Intrusion Method B table for dibromo-3-chloropropane;1,2- (96-12-8­). The Method B Indoor Air cancer-based cleanup level should be 1.1E-04 µg/m3 because the chemical is mutagenic and requires adjustments for early life exposure. This correction changed the VI-based groundwater and soil gas screening levels for this chemical.

  6. Updated the TPH generic indoor air screening level for the commercial worker to 390 µg/m3 in the Vapor Intrusion Worker table. We made this change because the maximum non-carcinogenic contribution from potential carcinogens (at their 1E-06 cancer risk level) within the petroleum mixture is only around 3%. The non-cancer inhalation reference dose for the EC 8-12 aliphatic fraction was used to develop this level consistent with the process described in Section E-7.2 of Ecology's vapor intrusion guidance (March 2022).

Main July 2022 update

  1. Added fifteen new hazardous substances, including 6 PFAS compounds, based on available toxicity data. We added a chemical-specific note for PFAS compounds.

    • benzo[e]pyrene
    • butyl alcohol, tert-
    • chlordane (alpha)
    • chlordane (gamma)
    • chlorotoluene
    • cresols
    • dibenzothiophene
    • ethyl tertiary butyl ether (ETBE). Also added to the vapor intrusion (VI) tables.
    • pentaerythritol tetranitrate (PETN)
    • PFAS compounds:
      • hexafluoropropylene oxide dimer acid (HFPO-DA; GenX)
      • perfluorobutanesulfonic acid (PFBS)
      • perfluorohexanesulfonic acid (PFHxS)
      • perfluorononanoic acid (PFNA)
      • perfluorooctanesulfonic acid (PFOS)
      • perfluorooctanoic acid (PFOA)

  2. Removed three hazardous substances from CLARC based on updates from EPA's Office of Pesticide Programs. There is no longer toxicity data for these pesticides:

    • cyhalothrin/karate
    • cypermethrin
    • db;2,4-

  3. Updated toxicity values for the following hazardous substances based on a review of EPA's May 2022 Regional Screening Level table:

    • Oral RfD: Office of Pesticide Programs Updates - acephate, asulam, butyric acid;4-(2-methyl-4-chlorophenoxy)-, chlorpropham, fomesafen, imazalil, norflurazon, oryzalin, oxyfluorfen, pirimiphos-methyl, s,s,s-tributylphosphorotrithioate, thiophanate-methyl
    • Inhalation RfC/RfDi: Acetone
    • Oral CPF: Nickel refinery dust

    No updates to inhalation IUR/CPFi.

  4. ARAR Updates.

    • Corrected the EPA CWA §304 marine aquatic life acute and chronic criteria for lead in CLARC. The EPA CWA §304 marine aquatic life acute and chronic criteria for lead are 210 and 8.1 µg/L, respectively.
    • Added pH Criteria. Washington state's (173-201A WAC) fresh and marine water pH levels are based on protection of aquatic life. These criteria are described in the pH notes.

  5. Added "Groundwater—Other Regulatory Criteria" column which includes:

    • State action levels (SALs) for PFAS chemicals: The Washington State Department of Health (DOH) established state action levels for five PFAS under WAC 246-290-315. The SALs provide state public health recommendations for the safe, long-term consumption of drinking water, below which there is no known or expected health risk. Ecology intends to evaluate whether the DOH SALs are “relevant and appropriate requirements” on a site-by-site basis using the criteria in WAC 173-340-710(4). If these MTCA requirements are met, Ecology will determine that the SALs are relevant and appropriate for that particular site. (See Ecology's PFAS Focus Sheet).
    • State secondary maximum contaminant levels (SMCLs): DOH has established secondary maximum contaminant levels (SMCLs) under WAC 246-290-310. Ecology clarified in its 2001 Concise Explanatory Statement (see Chapter 10.1.8) that SMCLs incorporated into the DOH regulations for public water supplies are an applicable state law and therefore an applicable standard under MTCA. SMCLs established by DOH under WAC 246-290-310 may be considered as ARARs when setting cleanup levels. Federal SMCLs for drinking water are considered advisory and are not ARARs under MTCA.

  6. Added default vapor intrusion (VI) risk-based screening levels for a commercial worker scenario (see new VI Wkr (calc) worksheet tab). These may apply at sites where adult workers inside of buildings are, or potentially are, the receptors that represent reasonable maximum exposure (RME) to VI-caused indoor air contamination. Reference CLARC's vapor intrusion commercial worker guidance (July 2022).

  7. Removed vapor intrusion deep soil gas screening levels. We no longer provide different screening levels for deep and shallow soil gas sampling. CLARC now has only shallow soil gas screening levels. This is consistent with the recommendations provided by EPA in their June 2015 VI Guidance and should lead to conservative decision making for most situations. Reference Section 3.6.2 in Ecology's Vapor Intrusion Guidance (2022).

  8. Added dermal exposure parameters (GI and ABS). For hazardous substances other than petroleum mixtures, evaluation of concurrent exposure (i.e., ingestion and dermal contact with soil) is only required under modified Method B and C, and then only under certain specified circumstances. The regulation does provide standard equations and default values for evaluating concurrent exposure for the soil pathway. However, CLARC does not provide pre-calculated Method B or C formula values using those standard equations and default values. The Gastrointestinal Absorption Conversion Factor (GI) and Dermal Absorption Fraction (ABS) are key exposure parameters for evaluating the dermal pathway. Recommended default values for these parameters as provided in the MTCA Cleanup Rule, and now included in CLARC, have been updated based on newer science contained in EPA’s RAGS Part E Guidance.

  9. Updated soil concentrations protective of groundwater in the vadose zone for organic chemicals that lack a Henry's law constant, but that have an available Kd value. In these cases, we conservatively used a Henry's law value of zero to make the calculation. It's noted that chemical loss due to volatilization based on Henry's law is not a major driver in the 3-phase partitioning model.


2024 | 2023 | 2022 | 2021 | 2020 | 2019 and earlier

July 2021

  1. New Guidance for assessing risk from early-life exposure to carcinogens. We developed this general CLARC guidance to address the increased childhood sensitivity (compared to adults) from carcinogens with a documented mutagenic mode of action. Consistent with EPA guidance, Age-Dependent Adjustment Factors (ADAFs) have been applied in the MTCA cleanup level calculations (with the exception of vinyl chloride) to address increased childhood sensitivity to mutagenic chemicals. Further adjustments using ADAFs are not needed for vinyl chloride because chemical-specific data on early life susceptibility are available and were used by EPA in deriving the slope factor. Chemicals in CLARC that have a documented mutagenic mode of action and are addressed in this guidance are listed below:


    Ecology applies a toxicity equivalence factor (TEF) approach when determining compliance with cleanup levels established for mixtures of carcinogenic polycyclic aromatic hydrocarbons (cPAHs).

    • Benzo(a)anthracene (56-55-3)
    • Benzo(a)pyrene (50-32-8)
    • Benzo(b)fluoranthene (205-99-2)
    • Benzo(k)fluoranthene (207-08-9)
    • Chrysene (218-01-9)
    • Dibenz(a,h)anthracene (53-70-3)
    • Indeno(1,2,3-cd]pyrene (193-39-5)

    Other contaminants

    • Acrylamide (79-06-1)
    • Benzidine (92-87-5)
    • Chromium (VI) (18540-29-9)
    • Coke Oven Emissions (8007-45-2)
    • 1,2-Dibromo-3-chloropropane (96-12-8)
    • Ethylene oxide (75-21-8)
    • Methylene Chloride (75-09-2)
    • 4,4’-methylene bis(2-chloroaniline) (101-14-4)
    • N-Nitrosodiethylamine (diethylnitrosamine) (55-18-5)
    • N-Nitrosodimethylamine (dimethylnitrosamine) (62-75-9)
    • N-nitroso-N-ethylurea (ethylnitrosourea) (759-73-9)
    • N-Nitroso-N-methylurea (methylnitrosourea) (684-93-5)
    • Trichloroethylene (TCE; 79-01-6)
    • 1,2,3-Trichloropropane (96-18-4)
    • Vinyl Chloride (75-01-4)

  2. Editorial updates (no substantive changes) the Polycyclic Aromatic Hydrocarbons and Benzo[a]pyrene: Changes to MTCA default cleanup levels for 2017 guidance.

  3. Updated Toxicity data and physical/chemical properties for petroleum mixtures guidance. The new guidance supersedes the 2006 guidance, Reference Doses for Petroleum Mixtures, surrounding the use of noncancer reference doses (RfDs) to calculate Method B and C cleanup levels for petroleum mixtures. We’ve incorporated the information provided in this updated guidance (i.e., updates to the physical/chemical properties) into Ecology’s Excel workbook tool (MTCA TPH Ver. 11.1) for calculating cleanup levels for petroleum contaminated sites.

  4. Updated Soil cleanup levels to protect groundwater (July 2021 CLARC guidance) to clarify the use of the Henry's law constant in calculating soil levels protective of groundwater in CLARC. Where available, we use a unitless Henry’s law constant at 13 degrees Celsius in the calculations based on typical groundwater temperatures in Washington state. If chemical-specific data is not available to derive a Henry’s law constant at 13 degrees Celsius, the Henry’s law constant at 25 degrees Celsius is now used in the calculation, if available. We also updated the guidance to reference Ecology Implementation Memo #10, which provides guidance on evaluating the potential for carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in soil to impact groundwater.

  5. Added chemical-specific values from the Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (RAIS) chemical database, where updates were not made in February 2021. We added chemical-specific data was for solubility, Henry's law, the distribution coefficient (Kd), and the soil organic carbon-water partitioning coefficient (Koc). We did not update chemical-specific data that are specifically incorporated within the MTCA Rule (e.g., data in Tables 747-1 to 747-4). There are no plans at this time to update the bioconcentration factors (BCFs).

    Note: updates to chemical-specific values may impact cleanup levels based on soil leaching and groundwater concentrations protective of vapor intrusion.

  6. Re-evaluated and updated chemical-specific Inhalation Correction Factor (INH), used in the cleanup equation for ingestion of potable groundwater (MTCA Equations 720-1 and -2), to reflect EPA's 2015 criteria of a chemical being sufficiently volatile (EPA, 2015). Chemicals considered sufficiently volatile include those with a Henry’s law > 1 x 10-5 atm-m3/mol or a vapor pressure > 1 mmHg. We used a Henry's law value at 25° Celsius in the evaluation because water is likely warmer coming out of the household tap, compared to an assumed groundwater temperature of 13° Celsius. The INH factor accounts for exposure to potential vapors from non-ingestion groundwater use such as showering and bathing. Volatile chemicals have an INH of 2. All other substances have an INH of 1.

    Reference: EPA, 2015. OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. OSWER Publication 9200.2-154. June 2015).

  7. Adopted Oral Slope Factor for Chromium VI. The California EPA (CalEPA) oral cancer slope factor of 0.5 kg-day/mg for Chromium VI will be used to calculate MTCA cleanup levels based on cancer effects through oral exposure routes (e.g., soil ingestion, tap water ingestion, etc.). Evidence of its carcinogenic effects by the oral route are based on studies on rats and mice conducted by the National Toxicology Program (NTP) in 2008 (NTP, 2008). The NTP indicated that oral exposure to Chromium VI provided clear evidence of carcinogenic activity in male and female rats and mice based on the presence of benign and malignant tumors in rat oral mucosa (i.e., mucous membrane lining the inside of the mouth) and mouse small intestine (NTP, 2008; EPA, 2013). California EPA's oral slope factor is based on a dose-related increase of tumors of the small intestine in male mice (NTP, 2008; CalEPA, 2011). EPA recognizes the CalEPA oral slope factor for Chromium VI as a valid Tier 3 toxicity value (EPA, 2013), and applies it in its Superfund cleanup work as part of their Regional Screening Level tables.

    Chromium VI also has a documented mutagenic mode of action, which will be accounted for in our cleanup calculations by application of Age-Dependent Adjustment Factors (to address early-life exposures; see our CLARC guidance on early-life exposure to carcinogens provided in Note 1 above).


    • CalEPA (California EPA), 2011. Public Health Goals for Chemicals in Drinking Water. Hexavalent Chromium (Cr VI). Pesticide and Environmental Toxicology Branch. Office of Environmental Health Hazard Assessment. California Environmental Protection Agency. July 2011.
    • EPA (Environmental Protection Agency), 2013. Tier 3 Toxicity Value White Paper. Regional Tier 3 Toxicity Value Workgroup. OSWER Human Health Regional Risk Assessors Forum. May 16, 2013.
    • National Toxicology Program (NTP), 2008. Toxicology and Carcinogenesis Studies of Sodium Dichromate Dihydrate (CAS No. 7789-12-0) in F344/N Rats and B6C3F1 Mice (Drinking Water Studies). Washington, DC: National Toxicology Program; NTP TR 546. July 2008.

  8. Published Petroleum concentrations protective of aquatic receptors in surface waters–Implementation Memo #23. There are no published state (173-201A) or federal (CWA 304) surface water aquatic life protective criteria for petroleum hydrocarbons. In their absence, we derived protective concentrations from studies published by Ecology’s Environmental Assessment Program. The memo provides gasoline and diesel range organic concentrations that are protective of aquatic receptors in marine and fresh surface waters. It also provides protective values for benzene, ethylbenzene, toluene, and xylenes (BTEX). These values can be applied at any MTCA cleanup site.

    We added a link in CLARC to a TPH Note that discusses IM 23. This link has been added for petroleum and BTEX compounds for Chapter 173-201A WAC Fresh and Marine Chronic Aquatic Life Criteria.

  9. Updated the chemical-specific note for asbestos.

  10. Updated the Oral CPF for Chromium VI based on a review of EPA's November 2020 Regional Screening Level table. There were no updates to Inhalation IUR/CPFi, Oral RfD, or Inhalation RfC/RfDi.

2004-2021 Updates