History of changes to CLARC

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.

Forty chemicals were eliminated from CLARC in the August 2020 update.

Chemical	Data Group	Chemical	Data Group	Chemical	Data Group
direct sky blue	Dyes	benzo(g,h,i)perylene	PAHs	chlorophenyl methyl sulfone;p-	SVOCs
niagara blue 4B	Dyes	carbazole	PAHs	chlorophenyl methyl sulfoxide;p-	SVOCs
nitrotoluenes;o-,m-,p-	Explosives	coal tar creosote	PAHs	cyclopentadiene	SVOCs
nitric oxide	Gases	PAHs	PAHs	monochlorobutanes (not in HSDB)	SVOCs
nitrogen dioxide	Gases	phenanthrene	PAHs	nitrosomethylvinylamine,n-	SVOCs
total dissolved solids	General Chemistry	carbophenothion	Pesticides	toluenediamine;2,4-	SVOCs
diethylene glycol	Glycols	chlorophenyl methyl sulfide;p-	Pesticides	toluenediamine;2,6-	SVOCs
diethylene glycol dinitrate	Glycols	dicofol	Pesticides	bis(2-chloroisopropyl) ether	VOCs
barium cyanide	Metal compounds	diethyl-p-nitrophenylphosphate	Pesticides	chloral	VOCs
vanadyl sulfate	Metal compounds	fensulfothion	Pesticides	chloropropane;2-	VOCs
lead alykyls	Metals (organometallic)	hexachlorocyclohexane;delta-	Pesticides	dimethylamine	VOCs
selenourea	Metals (organometallic)	mevinphos	Pesticides	methylcyclohexane	VOCs
sulfate	Nonmetal inorganics	perthane	Pesticides
acenaphthylene	PAHs	aminopyridine;4-

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.

List of chemicals assigned a different data group in the January 2020 CLARC update.

Chemical	New Data Group	Chemical	New Data Group
arsine	Gases	db;2,4-	Pesticides
lead alkyls	Metals (organometallic)	diphenylamine	Pesticides
phosphorus	Nonmetal inorganics	glufosinate-ammonium	Pesticides
sulfate	Nonmetal inorganics	nustar	Pesticides
bidrin	Pesticides	cyclohexylamine	VOCs
bromoxnil	Pesticides	diisopropyl methylphosphonate	VOCs
butyric acid;4-(2-methyl-4-chlorophenoxyl)p\-	Pesticides	dimethylaniline;N,N-	VOCs
chlordecone (kepone)	Pesticides	ethylene diamine	VOCs
chlorsulfuron	Pesticides	methyl styrene, alpha	VOCs

 

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

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.

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