What's new in CLARC

CLARC is a living document. Below is a list of minor edits/corrections we made since the publication of the August 2023 CLARC database.

1. CLARC Hyperlinks. Broken hyperlinks within the August 2023 CLARC Master Excel and PDF files have been fixed.

You'll find this same information in the first tab of the August 2023 CLARC spreadsheet. Many of the terms and abbreviations mentioned here are defined in the glossary.

What's new

1. New hazardous substances. New Hazardous Substances are highlighted blue in the table. Cyclohexene and Perfluorohexanoic Acid (PFHxA) have been added 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**. PFHxA (a PFAS compound) was added based on available toxicity data from EPA IRIS.

**Toxicity information for cyclohexene will be incorporated into our current CLARC guidance titled: Toxicity Data and Physical/Chemical Properties for Petroleum Mixtures. Information in the updated guidance on petroleum mixtures, anticipated to be ready in Fall 2023, will be incorporated into a new Excel Workbook tool (MTCATPH Ver. 12.0) for calculating cleanup levels for petroleum contaminated sites. The new MTCATPH Workbook tool is also anticipated to be ready for use in Fall 2023.

2. Toxicity value updates. Updated Toxicity Values are highlighted blue in the table. Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's May 2023 Regional Screening Level (RSL) Table. These updated toxicity values, including values for new chemicals, are highlighted blue in the table. Cells highlighted blue with with the text "[REMOVED]" means that the old value was removed.

• 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 document: 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. Chemical-specific values. Updated Chemical-Specific Values are highlighted blue in the table. The Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (RAIS) chemical database was reviewed in June 2023 to incorporate updates to chemical-specific data in CLARC.

• 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. Updates were made for 18 compounds. Formulas in EPA's Vapor Intrusion Screening Level (VISL) excel spreadsheet system (Chem Props worksheet) were used to make the adjustment.
• Solubility: Updates were made for chlorine dioxide, PFHxS (a PFAS compound), and white mineral oil.
• Vapor Pressure: Updates were made for phosphoric acid and thallium carbonate.
• Kd: An update was made for nickel refinery dust.
• Koc: An update was made for white mineral oil.
• INH: INH groundwater factors were updated for sodium azide and thallium carbonate to reflect that these are not volatile.
• GI and ABS (dermal parameters): Updates were made for DDT to reflect that it's not a volatile compound.

4. Updates to surface water ARARs: Changes to ARARs are highlighted blue.

• Cyanide 173-201A-240 Marine Acute and Chronic Aquatic Life Criteria: A link to a note was added to the cells that correspond 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.
• Methyl mercury: The freshwater and marine aquatic life CWA §304 criteria were removed. These criteria apply to total mercury, and were derived from data for inorganic mercury (II). A link to a note was added 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. Soil Leaching for Carcinogenic PAHs (cPAHs). Changes to the Soil Leaching to Groundwater to Surface Water Pathway for cPAHs are highlighted blue. 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 benzo(a)pyrene (BaP; WAC 173-340-708(8)(e)(iv)). As such, soil cleanup levels in CLARC protective of the groundwater discharge to surface water pathway for individual cPAHs, other than BaP, have been removed. 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. Vapor Intrusion Tables: Changes to the Vapor Intrusion (VI) Tables are highlighted blue. The hexachloroethane VI groundwater screening levels changed 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. The column named "Sub-Slab Soil Gas Screening Level" was re-named to: “Soil Gas Screening Level”. This change was made because there is no longer a distinction between shallow and deep soil gas screening levels.

7. Noncancer Effects Table: DDD and DDE were added to the noncancer effects table along with perfluorohexanoic acid (PFHxA).

Other notes

1. Hazardous Substances with Chemical-Specific Considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors. Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A column (Links to Important Notes) is included in the table, which contains links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific," while other links go to individual PDF documents.

2. Soil to Groundwater Cleanup Level Calculations. For default calculation of soil cleanup levels to protect groundwater, Henry's law constants at 13° Celsius should be used. Data from ORNL RAIS (i.e., boiling point, critical temperature, enthalpy of vaporization) along with formulas in EPA's Vapor Intrusion Screening Level (VISL) Excel spreadsheet system (Chem Props worksheet) were used to adjust Henry's law based on 25° Celsius to 13° Celsius. If chemical-specific data is not available to derive a Henry’s law constant at 13° Celsius, the Henry’s law constant at 25° Celsius is used in the calculation, if available. Soil protective of groundwater levels are provided for organics that have a Kd value, but no Henry's law constant in CLARC. A Henry's law value of zero was conservatively used for vadose zone soil 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. A Henry’s Law constant is not needed to calculate soil protective of groundwater cleanup levels for saturated zone soil since the default air-filled soil porosity is assumed to be zero.

3. Inhalation Toxicity Criteria. IRIS and other Ecology sources of toxicity data identify the inhalation reference concentration (RfC) and inhalation unit risk (IUR), and do not present conversions to an inhalation RfD (RfDi) or inhalation cancer potency factor (CPFi). For calculating cleanup levels based on inhalation exposure, MTCA expresses inhalation toxicity data as an inhaled dose or intake expressed as an RfDi or a CPFi — based on adjustments for body weight (70 kilograms) and breathing rate (20 m³/day). The conversion formulas are presented below:

• Inhalation RfC to RfDi - RfDi (mg/kg-day) = (RfC [mg/m³] ÷ 70 kg) x 20 m³/day
• Inhalation URF (IUR) to CPFi - CPFi (kg-day/mg) = (IUR [m³/µg] x 70 kg) ÷ (20 m³/day x 0.001 mg/µg)

4. Rounding. Cleanup levels are rounded to two significant figures. Values other than cleanup levels (such as toxicity values and other parameters used to calculate cleanup levels) may have more than two significant figures. For example, in making media transfer calculations such as estimating soil concentrations protective of groundwater, or estimating concentrations in groundwater or soil gas that are protective of indoor air, the full calculated risk-based value for the target concentration (in groundwater or indoor air) is used in the calculation. The final value in the media-transfer calculation is rounded to two significant figures.

5. Sources of toxicity values. Sources of cancer toxicity data that include a mutagenic mode of action are highlighted in orange/dotted pattern (see Source-M). The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations:

• Source-M (e.g., I-M, I-P, etc.) = Chemical is evaluated based on a mutagenic mode of action for early life exposure (hlighted in orange/dotted pattern with bold text). With the exception of vinyl chloride, age-dependent adjustment factors (ADAFs) were used in the cleanup level calculation.
• I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
• P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA's Superfund Health Risk Technical Support Center (STSC). (STSC is within EPA's Office of Research and Development's (ORD's) Center for Public Health and Environmental Assessment, formerly known as the National Center for Environmental Assessment [NCEA]).
• X = PPRTV Screening Level (does not meet all of requirements for a standard PPRTV value)
• A = ATSDR = Agency for Toxic Substances and Disease Registry
• C = Cal EPA = California Environmental Protection Agency
• D = EPA Office of Water
• G = See EPA's Regional Screening Level Users Guide
• H = HEAST = Health Effects Assessment Summary Table from EPA
• O = EPA Office of Pesticide Programs (OPP)
• S = Other State sources

Note: The oral cancer potency factor (CPF) for ethylbenzene and naphthalene from Cal EPA, and the inhalation unit risk for ethylbenzene from Cal EPA, have not been included in CLARC pending further evaluation.

You'll find this same information in the first tab of the January 2023 CLARC spreadsheet.  Many of the terms and abbreviations mentioned here are defined in the glossary. 

What's new

1. New hazardous substances. Perfluorobutanoic Acid (PFBA) has been added to CLARC based on available toxicity data from EPA IRIS.

2. Deleted substances. Two hazardous substances, dibenzothiophene and 1,2-dichloroethylene (mixed isomers), have been removed 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. Toxicity value updates. Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's November 2022 Regional Screening Level (RSL) Table. These updated toxicity values, including values for new chemicals, are highlighted blue in the table. Cells highlighted blue with with the text "[removed]" means that the old value was removed.

• 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.
• Oral CPF: No updates.
• Inhalation IUR/CPFi: No updates.

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

5. Additional chemicals with toxicity data from EPA's IRIS database were added 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. Note for white mineral oil.  A link to an "Important Note" has been added to explain why the Method B and C soil and groundwater levels for white mineral oil (CAS 8012-95-1) have been removed from CLARC.

7. Note for Chromium VI. Information regarding the derivation of the inhalation unit risk (IUR) of 8.4E-02 (µg/m3)-1 (assuming 100% Cr VI) has been added to the "Important Note" for Chromium VI.

8. 2,3,7,8-TCDD. The term "low organic" for 2,3,7,8-TCDD has been removed from the chemical name. Low organic corresponds to low organic soils. However, since the Method A and B soil levels for 2,3,7,8-TCDD provided in CLARC apply to all soil types, 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 40 CFR 131.45 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, our Policy 730 has been rescinded and all of the 40 CFR 131.45 values provided in CLARC (see columns AY and BF) have been restored to EPA's regulation. All of the surface water criteria under 40 CFR 131.45 provided in CLARC are applicable federal standards.

Note: 40 CFR 131.45 values for 2,3,7,8-TCDD and thallium provided in CLARC have been removed. 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. Guidance on the Use of Method A, B, and C Cleanup Levels and Mixing Methods. We have issued new guidance on using Methods A, B, and C for establishing cleanup levels. In this guidance, we summarize each cleanup method, and provide guidance on mixing methods.

11. CLARC's individual PDF files removed from webpage. Since CLARC's "Master PDF" file contains the entirety of CLARC's data tables and information, and since we've bookmarked the spreadsheet for easy navigation, we're no longer posting individual PDFs of each media table on CLARC's Data Table webpage.

Other Notes

1. Hazardous Substances with Chemical-Specific Considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors. Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A column (Links to Important Notes) is included in the table, which contains links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific," while other links go to individual PDF documents.   
2. Soil to Groundwater Cleanup Level Calculations.  For default calculation of soil cleanup levels to protect groundwater, Henry's law constants at 13° Celsius should be used. Data from ORNL RAIS (i.e., boiling point, critical temperature, enthalpy of vaporization) along with formulas in EPA's Vapor Intrusion Screening Level (VISL) Excel spreadsheet system (Chem Props worksheet) were used to adjust Henry's law based on 25° Celsius to 13° Celsius. If chemical-specific data is not available to derive a Henry’s law constant at 13° Celsius, the Henry’s law constant at 25° Celsius is used in the calculation, if available. Soil protective of groundwater levels are provided for organics that have a Kd value, but no Henry's law constant in CLARC. A Henry's law value of zero was conservatively used for vadose zone soil 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. A Henry’s Law constant is not needed to calculate soil protective of groundwater cleanup levels for saturated zone soil since the default air-filled soil porosity is assumed to be zero.
3. Inhalation Toxicity Criteria. IRIS and other Ecology sources of toxicity data identify the inhalation reference concentration (RfC) and inhalation unit risk (IUR), and do not present conversions to an inhalation RfD (RfDi) or inhalation cancer potency factor (CPFi). For calculating cleanup levels based on inhalation exposure, MTCA expresses inhalation toxicity data as an inhaled dose or intake expressed as an RfDi or a CPFi – based on adjustments for body weight (70 kilograms) and breathing rate (20 m3/day). The conversion formulas are presented below:
   • Inhalation RfC to RfDi - RfDi (mg/kg-day) = (RfC [mg/m3] ÷ 70 kg) x 20 m3/day
   • Inhalation URF (IUR) to CPFi - CPFi (kg-day/mg) = (IUR [m3/µg] x 70 kg) ÷ (20 m3/day x 0.001 mg/µg)
      
4. Rounding. Cleanup levels are rounded to two significant figures. Values other than cleanup levels (such as toxicity values and other parameters used to calculate cleanup levels) may have more than two significant figures. For example, in making media transfer calculations such as estimating soil concentrations protective of groundwater, or estimating concentrations in groundwater or soil gas that are protective of indoor air, the full calculated risk-based value for the target concentration (in groundwater or indoor air) is used in the calculation. The final value in the media-transfer calculation is rounded to two significant figures.

5. Sources of toxicity values. The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations:

• Source-M (e.g., I-M, I-P, etc.) = Chemical is evaluated based on a mutagenic mode of action for early life exposure (hlighted in orange/dotted pattern with bold text). With the exception of vinyl chloride, age-dependent adjustment factors (ADAFs) were used in the cleanup level calculation.
• I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
• P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA's Superfund Health Risk Technical Support Center (STSC). (STSC is within EPA's Office of Research and Development's (ORD's) Center for Public Health and Environmental Assessment, formerly known as the National Center for Environmental Assessment [NCEA]).
• X = PPRTV Screening Level (does not meet all of requirements for a standard PPRTV value)
• A = ATSDR = Agency for Toxic Substances and Disease Registry
• C = Cal EPA = California Environmental Protection Agency
• D = EPA Office of Water
• G = See EPA's Regional Screening Level Users Guide
• H = HEAST = Health Effects Assessment Summary Table from EPA
• O = EPA Office of Pesticide Programs (OPP)
• S = Other State sources

Note: The oral cancer potency factor (CPF) for ethylbenzene and naphthalene from Cal EPA, and the inhalation unit risk for ethylbenzene from Cal EPA, have not been included in CLARC pending further evaluation.

CLARC is a living document. Below is a list of minor edits/corrections we made to the July 2022 CLARC database.

1. Modifications have been made to the Dermal Exposure Parameters described in Note 8 of the July 2022 "What's new & Notes for CLARC" Master Excel tab. 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). However we have still retained the chemical-specific values from EPA's RAGS Part E. We've also added chemical-specific values from the Agency for Toxic Substances and Disease Registry (ATSDR) toxicological profiles for benzene, toleuene, ethylbenzene, and xylenes. On a site-specific basis, however, 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. Updates to Petroleum Guidance. Consistent with the discussion in the bullet above on dermal exposure parameters, we've also updated the ABS and GI dermal exposure parameters in two other resources:
   • July 2021 CLARC Petroleum Guidance, Toxicity Data and Physical/Chemical Properties for Petroleum Mixtures, and
   • Ecology's Excel Workbook tool (MTCA TPH Ver. 11.1) for calculating cleanup levels for petroleum contaminated sites.
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. Vapor Intrusion Tables. Acetone has been deleted from the vapor intrusion tables because it no longer has inhalation toxicity criteria (the ATSDR chronic inhalation reference concentration has been withdrawn).
5. The Vapor Intrusion (VI) Method B table was corrected 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 to account that the chemical is mutagenic and requires adjustments for early life exposure. This correction resulted in changes to the VI-based groundwater and soil gas screening levels for this chemical.
6. The TPH generic indoor air screening level for the commercial worker has been updated to 390 µg/m³ in the Vapor Intrusion Worker table. We made this update since 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).

You'll find this same information in the first tab of the July 2022 CLARC spreadsheet.  Many of the terms and abbreviations mentioned here are defined in the glossary. 

What's new

1. New Hazardous Substances. Fifteen new hazardous substances, which include 6 PFAS compounds,* have been added to CLARC based on available toxicity data. A chemical-specific note has been added for PFAS compounds (see Links to Important Notes (Column D) in the Master Spreadsheet).
   • hexafluoropropylene oxide dimer acid (HFPO-DA; GenX)
   • perfluorobutanesulfonic acid (PFBS)
   • perfluorohexanesulfonic acid (PFHxS)
   • perfluorononanoic acid (PFNA)
   • perfluorooctanesulfonic acid (PFOS)
   • perfluorooctanoic acid (PFOA)
   • 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)
2. Deleted Substances. Three hazardous substances have been removed from CLARC based on updates provided by EPA's Office of Pesticide Programs. There is no longer toxicity data for these three pesticides:
   • cyhalothrin/karate
   • cypermethrin
   • db;2,4-
3. Toxicity Value Updates. Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's May 2022 Regional Screening Level (RSL) Table. These updated toxicity values, including values for new chemicals, are highlighted blue in the table. Cells highlighted blue with no value means that the old value was removed.
   • 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 refinerary dust
   • Inhalation IUR/CPFi: No updates 
4. ARAR Updates.
   • Correction for Lead. The EPA CWA §304 marine aquatic life acute and chronic criteria for lead has been corrected 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 and are now in CLARC. These criteria are described in the pH notes.
5. New column: "Groundwater—Other Regulatory Criteria."  The following regulatory criteria have been added:
   • State Action Levels (SALs) for PFAS Chemicals: The Washington State Department of Health (DOH) established State Action Levels (SALs) 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, which should go live in late July 2022.] 
   • 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. Vapor Intrusion (VI) Risk-Based Screening Levels - Commercial Worker Scenario. We added default VI risk-based indoor air levels for a commercial worker scenario (see new Vapor Intrusion 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. VI Deep Soil Gas Screening Levels. Ecology no longer provides different VI screening levels for deep and shallow soil gas sampling locations. CLARC has been updated to only include 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. Soil Cleanup Levels to Protect Groundwater. Soil concentrations protective of groundwater in the vadose zone were updated for organic chemicals lacking a Henry's law constant, but have an available Kd value. In these cases, a Henry's law value of zero was conservatively used 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.

___________________________________________

Other notes

1. Hazardous Substances with Chemical-Specific Considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors. Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A column (Links to Important Notes) is included in the table, which contains links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific," while other links go to individual PDF documents.  
2. Henry Constants for Soil to Groundwater Cleanup Level Calculations. For default calculation of soil cleanup levels to protect groundwater, Henry's law constants at 13° Celsius should be used. Data from ORNL RAIS (i.e., boiling point, critical temperature, enthalpy of vaporization) along with formulas in EPA's Vapor Intrusion Screening Level (VISL) excel spreadsheet system (Chem Props worksheet) were used to adjust Henry's law based on 25° Celsius to 13° Celsius.
3. Inhalation Toxicity Criteria. IRIS and other Ecology sources of toxicity data identify the inhalation reference concentration (RfC) and inhalation unit risk (IUR), and do not present conversions to an inhalation RfD (RfDi) or inhalation cancer potency factor (CPFi). For calculating cleanup levels based on inhalation exposure, MTCA expresses inhalation toxicity data as an inhaled dose or intake expressed as an RfDi or a CPFi – based on adjustments for body weight (70 kilograms) and breathing rate (20 m3/day). The conversion formulas are presented below.
   • Inhalation RfC to RfDi - RfDi (mg/kg-day) = (RfC [mg/m³] ÷ 70 kg) x 20 m³/day
   • Inhalation URF (IUR) to CPFi - CPFi (kg-day/mg) = (IUR [m3/µg] x 70 kg) ÷ (20 m³/day x 0.001 mg/µg)
4. Rounding. Cleanup levels are rounded to two significant figures. Values other than cleanup levels (such as toxicity values and other parameters used to calculate cleanup levels) may have more than two significant figures. For example, in making media transfer calculations such as estimating soil concentrations protective of groundwater, or estimating concentrations in groundwater or soil gas that are protective of indoor air, the full calculated risk-based value for the target concentration (in groundwater or indoor air) is used in the calculation. The final value in the media-transfer calculation is rounded to two significant figures.
5. Sources of toxicity values. The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations:
   1. Source-M (e.g., I-M, I-P, etc.) = Chemical is evaluated based on a mutagenic mode of action for early life exposure (highlighted in orange/dotted pattern with bold text). With the exception of vinyl chloride, age-dependent adjustment factors (ADAFs) were used in the cleanup level calculation. Reference CLARC's early-life exposure guidance (July 2021). 
   2. I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
   3. P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA's Superfund Health Risk Technical Support Center (STSC)
      • (STSC is within EPA's Office of Research and Development's (ORD's) Center for Public Health and Environmental Assessment, formerly known as the National Center for Environmental Assessment [NCEA]).
   4. X = PPRTV Screening Level (does not meet all of requirements for a standard PPRTV value)
   5. A = ATSDR = Agency for Toxic Substances and Disease Registry

•       C = Cal EPA = California Environmental Protection Agency
•       D = EPA Office of Water
•       G = See EPA's Regional Screening Level Users Guide
•       H = HEAST = Health Effects Assessment Summary Table from EPA
•       O = EPA Office of Pesticide Programs (OPP)
•       S = Other state sources

You'll find this same information in the first tab of the July 2021 CLARC spreadsheet.  Many of the terms and abbreviations mentioned here are defined in the glossary. 

What's new

1. Guidance for assessing risk from early-life exposure to carcinogens. We developed a 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 in the table below. 

2. Updated PAH guidance. We made editorial updates to our CLARC guidance titled Polycyclic Aromatic Hydrocarbons and Benzo[a]pyrene: Changes to MTCA default cleanup levels for 2017. No substantive changes were made.

3. Updated petroleum guidance, Toxicity data and physical/chemical properties for petroleum mixtures. We updated our 2006 guidance surrounding the use of noncancer reference doses (RfDs) to calculate Method B and C cleanup levels for petroleum mixtures. The 2006 guidance, which was titled Reference Doses for Petroleum Mixtures, is superseded by this updated guidance. The information provided in this updated guidance (i.e., updates to the physical/chemical properties) has been incorporated 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). We updated this 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. This guidance has also been updated 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. Chemical-specific values. The Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (RAIS) chemical database was used to incorporate additional chemical-specific data where updates were not made in February 2021. Additional chemical-specific data was added for solubility, Henry's law, the distribution coefficient (Kd), and the soil organic carbon-water partitioning coefficient (Koc). Chemical-specific data in CLARC that are specifically incorporated within the MTCA Rule (e.g., data in Tables 747-1 to 747-4) were not updated. Also, there are no plans at this time to update the bioconcentration factors (BCFs). For an example screenshot of updated values in CLARC, see the "What's New & Notes for CLARC" tab in the July 2021 CLARC spreadsheet.

You'll find this same information in the first tab of the February 2021 CLARC spreadsheet. Many of the terms and abbreviations mentioned here are defined in the glossary.

What's new

• CAS numbers. We updated the CAS number for diquat which is now 2764-72-9. This is consistent with EPA's Regional Screening Level Table (RSL). Numbers that begin with "E" are EPA identification numbers used in the RSL and are used due to the lack of a CAS number. Information on alternative CAS numbers used in CLARC (for substances that do not have CAS numbers or an EPA identification number) is provided on the CLARC Data Tables webpage.
• Soil cleanup levels protective of groundwater to surface water. We now include soil cleanup levels protective of groundwater that discharges to fresh or marine surface water. These are calculated with the same “fixed parameter three-phase partitioning model” (described in WAC 173-340-747(4) and based on MTCA Equation 747-1) used for deriving soil concentrations that are protective of potable groundwater. A guidance document describing the Soil-to-Groundwater pathway and the derivation of the pre-calculated cleanup levels is available on Ecology’s CLARC webpage (see note below). Target groundwater and surface water concentrations used in the “fixed parameter three-phase partitioning model” are located in the Master excel spreadsheet immediately after their respective columns that present groundwater and surface water state and federal requirements (i.e., ARARs).
• Soil cleanup levels to protect groundwater (revised February 2021) We updated this CLARC guidance to include soil concentrations that are protective of groundwater that discharges to fresh or marine surface water.
• Chemical-specific values. We used the Oak Ridge National Laboratory (ORNL) Risk Assessment Information System (RAIS) chemical database to incorporate additional chemical-specific data where data was lacking in CLARC. Additional chemical-specific data was added for solubility, Henry's law, the distribution coefficient (Kd), and the soil organic carbon-water partitioning coefficient (Koc). Updates were not made for bioconcentration factors (BCFs). A reference column for each parameter that notes the source of the value listed is now included in CLARC. Data from ORNL RAIS (i.e., boiling point, critical temperature, enthalpy of vaporization) along with formulas in EPA's Vapor Intrusion Screening Level (VISL) excel spreadsheet system (Chem Props worksheet) were used to adjust Henry's law based on 25° Celsius to 13° Celsius. Additional updates are listed below.
  • Dimensional Henry's law constant (HLC) in atm-m3/mol was added to CLARC at both 25° and 13° Celsius.
  • Vapor pressure at 25° Celsius was added to CLARC. This is an important indicator of a chemical's potential for forming vapors.
• Vapor intrusion (VI) list of chemicals. A re-evaluation of the chemicals listed on the VI table was conducted based on EPA's 2015 criteria of a chemical being sufficiently volatile and toxic (EPA 2015). The list has been expanded from 62 to 87 chemicals, not including petroleum. It's noted that trans-1,2-Dichloroethylene, one of the daughter products of tetrachloroethylene (PCE), now has an inhalation reference concentration (RfC) and has been included on the VI tables. Chemicals on the VI tables have all been identified as being sufficiently volatile (i.e., Henry’s law > 1E-05 atm-m3/mol or a vapor pressure > 1 mmHg) and toxic under the VI pathway at a groundwater-soil system temperature of 13° Celsius. Chemicals that had been on the list but were removed because they didn't meet EPA's VI critieria include aldrin, bis(2-chloroethyl)ether, hydrogen cyanide, and nitrobenzene.
  • 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.
•  New hazardous substances. Fourteen new hazardous substances have been added to CLARC because they have available toxicity data from Cal EPA or EPA's PPRTV program (see below). 
  • aminobiphenyl, 4-; 
  • bis(2-chloroethoxy)methane; 
  • bromochloromethane; 
  • dichloro-2-butene, trans-1,4-; 
  • dichloropropane;1,3-; 
  • diisopropyl ether; 
  • dinitrotoluene, 2-Amino-4,6-; 
  • dinitrotoluene, 4-Amino-2,6-; 
  • isopropanol; 
  • lithium; 
  • nitroglycerin; 
  • pentachloroethane; 
  • pentane;n-; 
  • trichlorobenzene;1,2,3-
• State and Federal Levels (ARARs).
  • Added CWA 304 ambient water quality criteria (AWQC) fresh and marine acute and chronic critieria for methyl mercury. Federal CWA 304 AWQC marine acute and chronic criteria was updated for lead.
  • EPA 40 CFR 131.45 Federal Human Health Surface Water Quality Criteria. Effective June 2020, EPA withdrew the Washington-specific human health-based surface water quality criteria from federal regulation 40 CFR Subpart D 131.45, except for the federal criteria for arsenic, methylmercury, and bis(2-chloro-1-methylethyl) ether, which remain in place. This action is being legally challenged by the State of Washington and all of the 40 CFR Subpart D 131.45 criteria still remain in CLARC. For guidance on applying the 40 CFR Subpart D 131.45 values, see TCP Interim Policy 730: Taking into Account Federal Human Health Surface Water Quality Criteria under MTCA.
• Toxicity value updates. Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's November 2020 Regional Screening Level (RSL) Table. These updated toxicity values, including values for new chemicals, are highlighted in blue (no pattern) in the table. Cells highlighted in blue with no value means that the old value was removed.
  • Oral RfD: Updated for phenylenediamine, p-; phthalic acid;p-
  • Inhalation RfC/RfDi: Added for dichloroethylene;1,2-,trans and molybdenum.
  • Oral CPF: Updated for pentabromo-6-chloro-cyclohexane;1,2,3,4,5-; phenylenediamine;o-; tetrachlorotoluene;p,a,a,a,-
  • Inhalation IUR/CPFi: Added for chlorobenzotrifluoride;4-; updated for bromoethene; nitropropane;2-

Other Notes

• Hazardous substances with chemical-specific considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors.  Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A column titled Links to Important Notes is included in the table which contains links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific," while other links go to individual PDF documents.     
• Henry constants for soil to groundwater cleanup level calculations. For default calculation of soil cleanup levels to protect groundwater, Henry's law constants at 13° Celsius should be used. Data from ORNL RAIS (i.e., boiling point, critical temperature, enthalpy of vaporization) along with formulas in EPA's Vapor Intrusion Screening Level (VISL) excel spreadsheet system (Chem Props worksheet) were used to adjust Henry's law based on 25° Celsius to 13° Celsius.
• Inhalation toxicity criteria. IRIS and other Ecology sources of toxicity data identify the inhalation reference concentration (RfC) and inhalation unit risk (IUR), and do not present conversions to an inhalation RfD (RfDi) or inhalation cancer potency factor (CPFi). For calculating cleanup levels based on inhalation exposure, MTCA expresses inhalation toxicity data as an inhaled dose or intake expressed as an RfDi or a CPFi – based on adjustments for body weight (70 kilograms) and breathing rate (20 m3/day). The conversion formulas are presented below.
• Inhalation RfC to RfDi - RfDi (mg/kg-day) = (RfC [mg/m3] ÷ 70 kg) x 20 m3/day
• Inhalation URF (IUR) to CPFi - CPFi (kg-day/mg) = (IUR [m3/µg] x 70 kg) ÷ (20 m3/day x 0.001 mg/µg)
• Rounding. Cleanup levels are rounded to two significant figures.  Values other than cleanup levels (such as toxicity values and other parameters used to calculate cleanup levels) may have more than two significant figures. For example, in making media transfer calculations such as estimating soil concentrations protective of groundwater, or estimating concentrations in groundwater or soil gas that are protective of indoor air, the full calculated risk-based value for the target concentration (in groundwater or indoor air) is used in the calculation. The final value in the media-transfer calculation is rounded to two significant figures.
• Sources of toxicity values.  Sources of cancer toxicity data that include a mutagenic mode of action are highlighted in orange/dotted pattern (see I-M below).  The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations:
  • I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
  • I-M = Toxicity source is IRIS and the chemical is evaluated based on a mutagenic mode of action for early life exposure (highlighted in orange/dotted pattern with bold text). Age-dependent adjustment factors (ADAFs) as recommended in IRIS were used in the cleanup level calculation.
  • P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA's Superfund Health Risk Technical Support Center (STSC). (STSC is within EPA's Office of Research and Development's (ORD's) Center for Public Health and Environmental Assessment, formerly known as the National Center for Environmental Assessment [NCEA]).
  • X = PPRTV Screening Level (does not meet all of requirements for a standard PPRTV value)
  • H = HEAST = Health Effects Assessment Summary Table from EPA
  • C = Cal EPA = California Environmental Protection Agency
  • A = ATSDR = Agency for Toxic Substances and Disease Registry
  • O = EPA Office of Pesticide Programs
  • S = Other EPA sources

Note: The oral cancer slope factor for chromium (VI), ethylbenzene, and naphthalene from Cal EPA, and the inhalation cancer potency factor for ethylbenzene from Cal EPA, have not been included in CLARC pending further evaluation.

You'll also find this information in the first tab of the August 2020 CLARC spreadsheet. Many of the terms and abbreviations mentioned here are defined in the Glossary.

1. CAS numbers. We updated CAS numbers for the following chemicals: Coke Oven Emissions (E649830) and Polybrominated biphenyls (36355-01-8). Numbers that begin with "E" are EPA identification numbers and are used due to the lack of a CAS number. Note: CAS numbers in CLARC and EPA's Regional Screening Levels (RSL) table are consistent. The information on alternative CAS numbers on the CLARC Data Tables webpage has been updated to reflect this.

2. Revised guidance. We updated the April 2019 guidance Soil Cleanup Levels to Protect Groundwater to address editorial and clarity issues.

3. Soil protective of groundwater for saturated soil calculations. We made updates to include soil protective of groundwater levels for the saturated zone for organics that have a distribution coefficient (Kd) value, but no Henry's Law constant in CLARC. A Henry’s Law constant is not needed to calculate soil protective of groundwater cleanup levels for saturated zone soil since the default air-filled soil porosity is assumed to be zero. This change effects the following chemicals: aroclors 1254, 1260, and 1016; total PCBs; 2,3,4,6-tetrachlorophenol; pentachlorobenzene; and paraquat dichloride.

4.  Chemical-specific note for pH. This note was updated to reflect that a Soil Organic Carbon-Water Partitioning Coefficient (Koc) value reflective of a pH of 6.8 was used in the soil protective of groundwater calculations for the listed ionizing organic chemicals.

5. Chemical-specific values. A summary of updates: 

• polychlorinated biphenyls (PCBs): Calculated a Kd value using the defaults in MTCA Equation 747-2. A soil protective of groundwater level for the saturated zone was calculated.
• Aroclor 1254: Added a Koc value from EPA's 1994 Soil Screening Guidance. A soil protective of groundwater level for the saturated zone was calculated.
• Mercury and 1-Methylnaphthalene: Updated the Henry's Law constant at 13 Degrees Celsius. The groundwater screening level for vapor intrusion (VI) was updated for mercury.
• Nitrobenzene and bromomethane: Updated the solubility values based on EPA's 1996 Soil Screening Level Guidance.
• Koc was updated for: benzene, bis(2-chloroethyl)ether; chloroform; 1,1-dichloroethane; 1,3-dichloropropene; diethyl phthalate; and trichloroethylene. We used the full value from EPA's 1996 Soil Screening Level Guidance instead of the rounded value.

6.  Eliminated chemicals. We eliminated 40 chemicals/parameters from CLARC due to the lack of toxicity data, cleanup levels, and levels based on state and federal requirements.

7. Uranium soluble salts.  In 2020, we completed a consultation process with EPA and the Washington State Department of Health (DOH) on using oral minimal risk level (MRL) from ATSDR (Agency for Toxic Substances and Disease Registry) instead of the current IRIS oral RfD for soluble uranium. Both EPA and DOH concurred with Ecology's decision to use the ATSDR oral MRL over the IRIS oral RfD value. See Ecology's supplemental CLARC guidance on soluble uranium.

In 2002, EPA’s National Center for Environmental Assessment (NCEA), which manages IRIS, conducted a literature review for uranium and identified new relevant toxicological studies that may yield a change in the uranium oral reference dose (RfD). The existing uranium oral RfD in IRIS is based on a single-dose response study from 1949. In 2013, ATSDR conducted a comprehensive review and evaluation of available toxicity studies and derived an intermediate minimum risk level (MRL). See the ATSDR toxicological profile for uranium. The MRL is a dose that is likely to be without an appreciable risk of adverse noncancer effects over a specified duration of exposure. ATSDR concluded that continued exposure beyond an intermediate duration is not likely to induce more severe effects, and may be adequately protective of chronic exposures. The MRL derived by ATSDR for soluble uranium is 15 times lower (this yields lower cleanup levels) than the oral RfD published in IRIS.

In a memo dated December 21, 2016, the EPA Superfund Program recommended that the ATSDR MRL be used in place of the RfD in IRIS without any further adjustment to assess chronic oral exposures. We agree with EPA that ATSDR’s MRL was derived using better and more relevant data than the study that formed the basis for the RfD in IRIS, and is scientifically defensible. The techniques used by ATSDR to derive its RfD are consistent with those used by EPA’s IRIS program and those recommended in MTCA (WAC 173-340-708(7)(f)).

IRIS is undertaking a reassessment of the noncancer, nonradiological health effects of uranium via oral exposure. Uranium was included on the December 2015 IRIS Program multiyear agenda as a chemical having high priority for assessment development. Ecology will re-evaluate using the ATSDR oral MRL for uranium if and when IRIS is updated to provide a new noncancer oral RfD for soluble uranium.

8. Toxicity value updates.  Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's May 2020 Regional Screening Level Table.  Updated toxicity values are highlighted in blue in the table. Cells highlighted in blue with no value means that the old value was removed.

• Inhalation RfC/RfDi: Added for antimony.
• Inhalation IUR/CPFi: Removed for chlorothalonil and 2-methoxy-5-nitroaniline; updated for direct black 38, direct blue 6, and direct brown 95.
• Oral RfDo: Updated for uranium, soluble salts.
• Oral CPFo: Added for nickel refinery dust; updated for chlorothalonil and direct black 38.

OTHER NOTES

1. Hazardous substances with chemical-specific considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors.  Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A column called "Links to Important Notes" is included in the table, which contains links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific," while other links go to individual PDF documents.  

2. Henry Constants for soil to groundwater cleanup level calculations. For default calculation of soil cleanup levels to protect groundwater, Henry Constants at 13 degrees Celsius should be used.  For total xylenes, the 13 degree Celsius Henry Constant in CLARC was calculated as the mean of the individual values of the 3 isomers.

3.  Sources of toxicity values.  The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations. Sources of cancer toxicity data that include a mutagenic mode of action are highlighted in orange/dotted pattern (see I-M):

      I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
      I-M = Toxicity source is IRIS and the chemical is evaluated based on a mutagenic mode of action for early life exposure
            (highlighted in orange/dotted pattern with bold text)
      P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA's Superfund Health Risk Technical Support Center (STSC)
            (STSC is within EPA's Office of Research and Development's (ORD's) Center for Public Health and Environmental
            Assessment, formerly known as the National Center for Environmental Assessment [NCEA]).
      X = PPRTV Screening Level (does not meet all of requirements for a standard PPRTV value)
      H = HEAST = Health Effects Assessment Summary Table from EPA
      C = Cal EPA = California Environmental Protection Agency
      A = ATSDR = Agency for Toxic Substances and Disease Registry
      O = EPA Office of Pesticide Programs
      S = Other EPA sources

Note: The oral cancer slope factor for chromium (VI), ethylbenzene, and naphthalene from Cal EPA, and the inhalation cancer potency factor for ethylbenzene from Cal EPA, have not been included in CLARC pending further evaluation.

You'll also find this information in the first tab of the January 2020 CLARC spreadsheet. Terms and abbreviations mentioned here are defined in the Glossary.

1. New hazardous substances. Two new hazardous substances have been added to CLARC because they are listed in applicable state and federal water laws or applicable toxicity data (see below).

• cobalt;
• paraquat dichloride (added to CLARC in place of paraquat).

2. Groundwater applicable state and federal laws.

Mercuric chloride: The state and federal MCL and federal MCLG of 2 µg/L was added to CLARC for mercuric chloride. The levels identified for mercury also apply to other inorganic forms such as mercuric chloride. The MCL is based on potential health effects to the kidney. The kidney is the critical organ of toxicity for the ingestion of mercuric salts.

3. CAS numbers. CAS numbers were updated for the following chemicals:

Nickel refinery dust (E715532), hexachlorodibenzo-p-dioxin, mixture (34465-46-8), crotonaldehyde (123-73-9), Refractory Ceramic Fibers (E715557), uranium, soluble salts (7440-61-1), and dinitrotoluene mixture; 2,4-2,6- (E1615210).  Numbers that begin with "E" are EPA identification numbers and are used due to the lack of a CAS number. Note - the information on alternative CAS numbers on the CLARC/Data tables webpage has been updated to reflect these changes.

4. Chemical data groups. Metal elements that are bounded to another element (e.g., aluminum phosphide) were identified as "Metal Compounds". Other changes where chemicals were assigned to a different data group are in the table below.

5.  GI Absorption Fraction. The heading for this parameter was changed to "AB1 GI Absorption Fraction." The change was made so that it is not confused with the GI absorption conversion factor (see WAC 173-340-740(3)(b)(iii)((B)) which is used to convert an oral toxicity factor, expressed as an administered dose, to an absorbed dose. To evaluate the dermal pathway, the oral toxicity factor is adjusted if necessary to represent an absorbed dose. The AB1 GI absorption fraction parameter is an estimate of relative oral bioavailability of a chemical.

6.  INH Inhalation Correction Factor. The heading for this parameter was changed to "INH Ground Water Inhalation Correction Factor." The change was made to reflect that this parameter accounts for potential exposure to hazardous substances (via the groundwater pathway) which may be volatilized and inhaled during showering and other domestic activities.

7. Soil protective of groundwater. Soil protective of groundwater concentrations were updated for the chemicals below (revised target groundwater concentrations are in parenthesis).

• Ethylene dibromide (0.05 µg/L - MCL);
• 1,1,2-trichloroethane;1,1,2 (3 µg/L - MCLG)

8.  Rounding. Cleanup levels are rounded to two significant figures.  Values other than cleanup levels (such as toxicity values and other parameters used to calculate cleanup levels) may have more than two significant figures. For example, in making media transfer calculations such as estimating soil concentrations protective of groundwater, or estimating concentrations in groundwater or soil gas that are protective of indoor air, the full calculated risk-based value for the target concentration (in groundwater or indoor air) is used in the calculation. The final value in the media-transfer calculation is rounded to 2 significant figures.

9.  Mutagenic chemicals/Early-life exposure. Cleanup levels for carcinogenic substances with a mutagenic mode of action are lowered by applying age-dependent adjustment factors (ADAFs) to account for increased childhood toxicity. Substances in IRIS that are identified as having a mutagenic mode of action with a recommendation of applying ADAFs include benzo(a)pyrene (oral and inhalation), trichloroethylene (oral and inhalation), acrylamide (oral and inhalation), ethylene oxide (inhalation), methylene chloride (oral and inhalation), and 1,2,3-trichloropropane (oral). MTCA Method B cancer cleanup level equations for these chemicals incorporate ADAFs to account for the increased risk in early-life versus later-life exposure. MTCA Method C cleanup equations are based on adult exposure and do not incorporate early-life exposure adjustments using ADAFs. However, if a non-industrial site qualifies for setting a Method C cleanup level (for groundwater, surface water, or air) based on the criteria in WAC 173-340-706(1)(a), then the Method C cleanup level will need to be adjusted lower using ADAFs to account for early life exposure.

10. Vapor Intrusion (VI) tables. Additional links to VI guidance were added along with default soil gas screening levels for petroleum hydrocarbons. Additional changes are below.

• TCE - The Method B cancer based indoor air cleanup level was corrected to be 0.33 µg/m³ (not 0.37 µg/m³) based on adjustments for early-life exposure. The Method C cancer based indoor air concentration was corrected to be 6.1 µg/m³ (not 6.3 µg/m³).
• Other mutagens - In addition to TCE, Method B indoor air cancer cleanup levels were adjusted for early-life exposure for the following: ethylene oxide and methylene chloride (see note 9 above on mutagenic chemicals).
• Rounding changes - Groundwater and/or soil gas screening levels slightly changed for the following chemicals due to the full calculated indoor air or groundwater cleanup level value being used in vapor pathway fate and transport equations: bromobenzene and vinyl chloride (see note 8 above on Rounding).

11. Trichloroethylene (TCE) and PAH/Benzo[a]pyrene (BaP) May 2019 CLARC guidance. CLARC guidance for these mutagenic chemicals were updated to reflect the following:

• Default MTCA Method C cleanup levels for these chemicals are based on adult exposure and do not incorporate early-life exposure (ELE) adjustments using Age-Dependent Adjustment Factors (ADAFs) - see note 9 above on mutagenic chemicals.
• Method B cancer based cleanup levels for these chemicals were adjusted for early-life exposure for all media (i.e., soil, groundwater, surface water and air). For surface water, the MTCA regulation does not include a default child-specific fish consumption rate (FCR). As such, the FCR for the child was conservatively assumed to be equal to that of the adult.
• TCE guidance revised Jan 2020
• cPAH guidance revised Jan 2020

12. Inhalation toxicity criteria. For reference, columns displaying the noncancer inhalation reference concentration (RfC) and the carcinogenic inhalation unit risk factor (IUR) were added to CLARC. IRIS identifies the RfC and IUR, and does not present conversions to an inhalation RfD (RfDi) or inhalation cancer potency factor (CPFi). For calculating cleanup levels based on inhalation exposure, MTCA expresses inhalation toxicity data as an inhaled dose or intake expressed as an RfDi or a CPFi – based on adjustments for body weight (70 kilograms) and breathing rate (20 m3/day). The conversion formulas are presented below.

• Inhalation RfC to RfDi - RfDi (mg/kg-day) = (RfC [mg/m³] ÷ 70 kg) x 20 m³/day
• Inhalation URF (IUR) to CPFi - CPFi (kg-day/mg) = (IUR [m³/µg] x 70 kg) ÷ (20 m³/day x 0.001 mg/µg)

13.  Carcinogenic PAHs (cPAHs). The six CalEPA inhalation cancer potency factors identified for cPAHs (other than benzo(a)pyrene) were removed along with their respective air cleanup levels. Same as for the oral exposure route, the toxicity equivalence factor (TEF) methodology also applies for the inhalation route of exposure in calculating cleanup levels for cPAH mixtures.  See Implementation Memo #10.

14. Archived pesticide assessments in IRIS. EPA's IRIS has archived 51 chemical assessments for pesticides and for these pesticides has instead recommended the use of the toxicity values from their Office of Pesticide Programs. These 51 pesticides will not be re-assessed by the IRIS program, but have been preserved for reference only. Toxicity data from EPA's OPP for these 51 pesticides have been incorporated into CLARC.

15. Bromobenzene. 640 mg/kg is the Method B noncancer soil cleanup level. It was incorrectly identified as the Method B cancer soil cleanup level in the May 2019 update.

16. Refractory ceramic fibers. The May 2019 CLARC incorrectly used the inhalation RfD in fibers/cm³ to calculate Method B and C noncancer air cleanup levels. These have been removed. The unit of measure for the inhalation noncancer toxicity criteria is now presented in units of fibers/m³.

17.  Noncancer effects table. This is a separate table containing, by exposure route (i.e., oral ingestion and inhalation), noncancer critical effects and target organs. Noncancer critical effects and target organs were updated for the 51 pesticides archived in IRIS. The updates were based on identified toxicity data from EPA's Office of Pesticide Programs.

The information provided in the noncancer effects table, which was primarily compiled based on information from EPA’s IRIS database, can be used to calculate hazard indices for groups of chemicals with similar types of noncancer effects.  This information was compiled for chemicals with noncancer toxicity criteria in IRIS and from EPA's Office of Pesticide Programs.

Note that there is not a table showing carcinogenic tumor types. For cancer causing chemicals (a.k.a., carcinogens), the total cancer risk is derived by summing the cancer risk for all chemicals of concern.  This approach is in accordance with MTCA and is consistent with EPA guidelines in which risks associated with carcinogens are considered additive with the same toxicological endpoint (i.e., cancer).

18.  Toxicity value updates. Updated toxicity values are highlighted in yellow (no pattern) in the January 2020 CLARC spreadsheet. Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's November 2019 Regional Screening Level Table.  Updated toxicity values are highlighted in yellow in the table. Cells highlighted in yellow with no value means that the old value was removed.

• 51 pesticides (updated with OPP toxicity values - see note 14 above on archived pesticides in IRIS)
• Trichloroethylene - Rounded the oral CPF to 4.6E-02 kg-day/mg (rather than using 4.64E-02 kg-day/mg). This is consistent with the value as presented in IRIS.
• 4-nitroaniline (added an oral CPF)
• Tetrachlorotoluene;p,a,a,a,- (added an oral RfD)

OTHER NOTES

1.  Hazardous substances with chemical-specific considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors. Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A column (Links to Important Notes) is included in the table which contains links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific", while others go to individual PDF documents.     

2.  Henry Constants for soil to groundwater cleanup level calculations. For default calculation of soil cleanup levels to protect groundwater, Henry Constants at 13 degrees Celsius should be used. For total xylenes, the 13 degree Celsius Henry Constant in CLARC was calculated as the mean of the individual values of the 3 isomers. 

3.  Sources of toxicity values. Sources of cancer toxicity data that include a mutagenic mode of action are highlighted in orange/dotted pattern in the January 2020 CLARC spreadsheet (see I-M). The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations:

• I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
• I-M = Toxicity source is IRIS and the chemical is evaluated based on a mutagenic mode of action for early life exposure (highlighted in orange/dotted pattern with bold text)
• P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA's Superfund Health Risk Technical Support Center (STSC). (STSC is within EPA's Office of Research and Development's (ORD's) Center for Public Health and Environmental Assessment, formerly known as the National Center for Environmental Assessment [NCEA]).
• X = PPRTV Screening Level (does not meet all of requirements for a standard PPRTV value)
• H = HEAST = Health Effects Assessment Summary Table from EPA
• C = Cal EPA = California Environmental Protection Agency
• A = ATSDR = Agency for Toxic Substances and Disease Registry
• O = EPA Office of Pesticide Programs
• S = Other EPA sources

Note that the oral cancer slope factor for chromium (VI) from the New Jersey Department of Environmental Protection and the oral and inhalation cancer potency factors for ethylbenzene from Cal EPA have not been included in CLARC pending further evaluation.

You can also find this information in the first tab of the May 2019 CLARC spreadsheet interim update.

1. Hazardous substances with chemical-specific considerations. For some hazardous substances, potential default cleanup levels may require special calculations or consideration of site-specific factors. Examples include benzo[a]pyrene/cPAHs, and hardness-dependent metals criteria for applicable state and federal fresh surface water laws. Many of these hazardous substances are listed in the CLARC tables with CAPITAL LETTERS and gray-shaded cells. A new column (Links to Important Notes) has been added to the table which contain links to relevant information. Many of the links go to a worksheet in this spreadsheet labeled "Notes - Chemical-Specific" while others go to individual PDF documents.     
2. Surface water - Applicable state and federal laws. Many surface water criteria have changed due to updates in EPA's National Recommended Water Quality Criteria (304[a]) in 2015 and 2016,  Ecology's Water Quality Standards (WAC 173-201A) in 2016, and EPA's 2016 "Revision of Certain Federal Water Quality Criteria Applicable to Washington" (40 CFR 131.45; formerly the Washington criteria were in 40 CFR 131.36, referred to as the National Toxics Rule, or NTR). There are two new columns containing Ecology's 201A Human Health criteria (one for fresh water and one for marine water). In the past, all of the 201A and NTR Human Health numbers were the same and were listed in the NTR column; there was no 201A Human Health column. Also, four columns containing the Aquatic Life Criteria from EPA's National Toxics Rule have been deleted because they are not applicable to Washington.
3. Surface Water spreadsheet column rearrangement. The Surface Water columns have been rearranged, with all of the fresh water columns on the left and all of the marine water columns on the right.
4. PAHs and Benzo[a]pyrene. In January 2017, EPA published new cancer and noncancer toxicity values for benzo[a]pyrene in IRIS.  The new cancer potency factor is lower than the old one, meaning that new cleanup levels calculated with the MTCA equations will be higher (less stringent) than old ones.  However, because EPA concluded that benzo[a]pyrene causes cancer by a mutagenic mode of action, cleanup levels were subsequently lowered by applying age-dependent adjustment factors to account for increased childhood toxicity.
5. Carcinogenic PAHs other than Benzo[a]pyrene. The Toxicity Equivalent Factors (the cancer potency relative to benzo[a]pyrene) for the seven carcinogenic PAHs listed in MTCA Table 708-2 are unchanged. However, while TEQ calculations are done the same as before, the TEQ should now be compared to the new cleanup level for benzo[a]pyrene and not the old one.   Since the TEQ method is required for carcinogenic PAHs, the individual cancer potency factors for the other six carcinogenic PAHs have been deleted from CLARC to reduce confusion.
6. Manganese. The oral reference dose of 0.14 mg/kg-day includes manganese from all sources, including diet.  The use of a modifying factor of 3 was applied to the oral reference dose for non-diet related exposures as recommended in IRIS (i.e., the reference dose was divided by 3). This generates a modified oral reference dose of 0.0467 mg/kg-day to be applied to non-food sources such as soil and water.  The reasons for this adjustment are described in EPA’s IRIS summary.
7. Henry Constants for soil to groundwater cleanup level calculations. For default calculation of soil cleanup levels to protect groundwater, Henry Constants at 13 degrees Celsius should be used. For total xylenes, the 13 degree Celsius Henry Constant in CLARC was calculated as the mean of the individual values of the 3 isomers.
8. New Hazardous Substances. Twenty-eight new hazardous substances have been added to CLARC because they are listed in applicable state and federal water laws or have been added to EPA's IRIS toxicity database: 1) asbestos; 2) bromoacetic acid; 3) bromobenzene; 4) cerium oxide and cerium compounds; 5) chlordecone (kepone); 6) chlorocresol; 7) dibromoacetic acid; 8) dichloramine; 9) dichloroacetic acid; 10) dinitrophenols; 11) DNOC; 12) endosulfan sulfate; 13) endosulfan;alpha; 14) endosulfan;beta; 15) endrin aldehyde; 16) guthion; 17) hexanone;2-; 18) nitroaniline, 4-; 19) nonylphenol; 20) phosgene; 21) propionaldehyde; 22) tetrahydrofuran; 23) toluene-2,4-diisocyanate; 24) toluene-2,6-diisocyanate; 25) tributyltin; 26) trichloramine; 27) trichloroacetic acid; 28) trimethylbenzene;1,2,3-
9. Toxicity value updates. Toxicity values in CLARC for the following hazardous substances have been changed based on a review of EPA's May 2019 Regional Screening Level Table.  Updated toxicity values are highlighted in yellow in the CLARC Master Excel: 1) ammonia; 2) benzaldehyde; 3) benzo(a)pyrene; 4) butadiene, 1,3-; 5) chloronitrobenzene;p-; 6) DDD; 7) DDE; 8) dibromochloromethane; 9) dichloropropane;1,2-; 10) dicyclopentadiene; 11) dimethylaniline;N,N-; 12) dinitrotoluene mixture; 2,4-/2,6-; 13) endosulfan sulfate; 14) ethylene oxide; 15) formaldehyde; 16) heptane;n-; 17) methylaniline;2-; 18) pentabromo-6-chloro-cyclohexane;1,2,3,4,5-; 19) phenylenediamine;o-; 20) rdx; 21) refractory ceramic fibers; 22) thallic oxide; 23) thallium acetate; 24) thallium chloride; 25) thallium nitrate; 26) thallium selenite; 27) toluene diisocyanate mixture;2,4-/2,6-; 28) toxaphene; 29) trichloro-1,2,2-trifluoroethane;1,1,2-; 30) trimethylbenzene;1,2,4-; 31) trimethylbenzene;1,3,5-
10. Noncancer effects table. A separate table containing, by exposure route (i.e., oral ingestion and inhalation), noncancer critical effects and target organs was added. The information provided in the noncancer effects table, which was compiled based on information from EPA’s Integrated Risk Information System (IRIS) database, can be used to calculate hazard indices for groups of chemicals with similar types of noncancer effects. This information was only compiled for chemicals with noncancer toxicity criteria in IRIS.  Note that there is a not a table showing carcinogenic tumor types. For cancer-causing chemicals (a.k.a., carcinogens), the total cancer risk is derived by summing the cancer risk for all chemicals of concern. This approach is in accordance with MTCA and is consistent with EPA guidelines in which risks associated with carcinogens are considered additive with the same toxicological endpoint (i.e., cancer).
11. Chemical data groups. A column containing  an assigned chemical data group for each chemical was added. Note that chemical data groups may overlap (e.g., naphthalane may be considered a PAH and a VOC).
12. Chemical synonyms. A column (see the last column in the Master CLARC Spreadsheet) that contains an expanded list of synonyms for chemicals in CLARC was added.  This list was generated from Ecology's Environmental Information Management System (EIM) database. 
13. Rounding. Cleanup levels are rounded to two significant figures. Values other than cleanup levels (such as toxicity values and other parameters used to calculate cleanup levels) may have more than two significant figures.
14. Sources of toxicity values.  The source of each toxicity value is listed in the Excel and PDF files using the following abbreviations:

• I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
• H = HEAST = Health Effects Assessment Summary Table from EPA
• C = Cal EPA = California Environmental Protection Agency
• A= ATSDR = Agency for Toxic Substances and Disease Registry
• P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA
• X = PPRTV Appendix from EPA
• S = Other EPA sources

1. Soil Cleanup Levels Protective of Groundwater. We now include soil cleanup levels protective of groundwater for many chemicals, calculated with the “fixed parameter three-phase partitioning model” (described in WAC 173-340-747(4) and based on MTCA Equation 747-1). These are available in the CLARC Master Excel in Data Tables in the “Soil Methods B & A unrestricted” tab and in the "Soil-Method B and Method A (unrestricted land use) PDF" CLARC Master PDF in Data Tables. A guidance document describing the Soil-to-Groundwater pathway and the derivation of the pre-calculated cleanup levels is available at Soil Cleanup Levels to Protect Groundwater, as well as from the guidance links at the top of the columns within the Excel and PDF documents.
2. Vapor Intrusion Screening Level Table. Vapor intrusion screening levels are now included in the CLARC Master Excel Table and in separate PDF files with links on the CLARC Data Tables page. These are revisions of Table B-1 from Ecology’s draft 2009 document, Guidance for Evaluating Soil Vapor Intrusion in Washington State: Investigation and Remedial Action, Ecology Publication 09-09-047.
3. Toxicity Value Updates. Toxicity values in CLARC for the following hazardous substances have been changed to be consistent with those in EPA’s Regional Screening Level Tables:
   • Direct black 38 (CAS 1937-37-7)
   • Direct blue 6 (CAS 2602-46-2)
   • Direct brown 95 (CAS 16071-86-6)
   • Ethyl acrylate (CAS 140-88-5)4.
4. Corrections to Groundwater Cleanup Levels:
   • Copper (CAS 7440-50-8) — calculated Method B (changed from 320 µg/L to 640 µg/L)
   • Copper (CAS 7440-50-8) — calculated Method C (changed from 700 µg/L to 1400 µg/L)
   • Arsenic, inorganic (CAS 7440-38-2) — Washington State Maximum Contaminant Level (changed from 100 µg/L to 10 µg/L)
   • Bromodichloromethane (CAS 75-27-4) — Washington State Maximum Contaminant Level (changed from 0.08 to 80 µg/L)
   • Chlorine (CAS 7782-50-5) — Washington State Maximum Contaminant Level (changed from 4 µg/L to 4000 µg/L)
   • Chlorine Dioxide (CAS 10049-04-4) — Washington State Maximum Contaminant Level (changed from 80 µg/L to 800 µg/L)
   • Ethylbenzene (CAS 100-41-4) — Washington State Maximum Contaminant Level (changed from 70 µg/L to 700 µg/L)
   • Glyphosate (CAS 1071-83-6) — Washington State Maximum Contaminant Level (changed from 70 µg/L to 700 µg/L)
5. ​​Updates to the Trichloroethylene Guidance Document. The cleanup levels and toxicity values have not changed. Parts of the guidance document were revised to provide clarification about the derivation of the cleanup levels: Trichloroethylene (TCE): Deriving Cleanup Levels under the Model Toxics Control Act (MTCA).
6. National Recommended Water Quality Criteria. Changes to the National Recommended Water Quality Criteria, published by EPA in June 2015, have not been incorporated into the CLARC Surface Water tables at this time.

In May 2014, we made significant changes to CLARC

1. We disabled the searchable chemical substance database. To find information:
   • We moved cleanup level information to an Excel spreadsheet and pdf files. The information can now be accessed in the CLARC data tables. The files contain Methods A, B, and C cleanup levels; Applicable or Relevant and Appropriate Requirements (ARARs), toxicity values; and physical parameters.
   • Future plans include the addition of simplified cleanup level calculations for the soil-to-groundwater pathway, the vapor intrusion pathway, and terrestrial ecological evaluation.
2. Other updates in May 2014:
   • We updated many toxicity values to be consistent with EPA’s November 2013 Regional Screening Level (RSL) tables. The list of hazardous substances in CLARC is unchanged.
   • We expanded the sources of toxicity values to include those from the California Environmental Protection Agency (Cal-EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR). However, the New Jersey Department of Environmental protection oral slope factor for chromium (VI) and the Cal-EPA oral and inhalation cancer potency factors for ethylbenzene are not included pending further evaluation. CLARC toxicity values come from:
     • I = IRIS (Integrated Risk Information System) database from the Environmental Protection Agency (EPA)
     • H = HEAST = Health Effects Assessment Summary Table from EPA
     • C = Cal EPA = California Environmental Protection Agency
     • A = ATSDR = Agency for Toxic Substances and Disease Registry
     • P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA
     • X = PPRTV Appendix from EPA
     • S = Other EPA sources
   • The updates to toxicity values in CLARC resulted in the following changes: 186 toxicity values were added, 36 were changed, and one was deleted.
   • We added Inhalation Correction Factors for chemicals that did not previously have them. This allows the calculation of Method B and Method C groundwater cleanup levels for additional chemicals.

For additional details regarding these changes, please see the contact information at the bottom this webpage.

Summary of changes to CLARC made between June 2004 and September 2012