Regional Screening Levels (RSLs) - What's New

 

Regional Screening Levels (RSLs)

To download the most recent Regional Screening Level tables, please go to the Generic Tables page. For assistance/questions please use the RSL Contact Us page.

The What's New section keeps users informed of changes to: toxicity values, exposure parameters, chemical-specific parameters, equation formats and any other SL changes. Please check this site frequently to be advised of any recent changes.

November 13, 2024

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • Chemicals with new toxicity values due to IRIS updates are:
    • Chromium (VI) has a new chronic RfD, chronic RfC, oral slope factor, and inhalation unit risk.
    • Formaldehyde has a new chronic RfC and inhalation unit risk.
    • Perfluorodecanoic acid (PFDA) was added, with a chronic and subchronic RfD.
    • Perfluorodecanoate was added, with a chronic and subchronic RfD based on molecular weight adjustment from PFDA.
    • Ammonium perfluorodecanoate was added, with a chronic and subchronic RfD based on molecular weight adjustment from PFDA.
    • Potassium perfluorodecanoate was added, with a chronic and subchronic RfD based on molecular weight adjustment from PFDA.
    • Sodium perfluorodecanoate was added, with a chronic and subchronic RfD based on molecular weight adjustment from PFDA.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • 2,3-Benzofluorene was added, with a screening chronic and subchronic RfD.
    • Dimethyl sulfide was added, with a screening chronic and subchronic RfD and screening chronic and subchronic RfC.
    • Delta-hexachlorocyclohexane was added, with a screening chronic and subchronic RfD.
    • Isopropyltoluene was added, with a screening chronic and subchronic RfD and screening chronic and subchronic RfC.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Acrolein has a new DRAFT subchronic RfD and subchronic and chronic RfC.
    • n-Hexane has a new DRAFT subchronic RfD and subchronic RfC.
    • 1-Methylnaphthalene has a new DRAFT subchronic and chronic RfD and subchronic RfC.
    • 2-Methylnaphthalene has a new DRAFT chronic RfD and subchronic RfC.
    • Naphthalene has a new DRAFT subchronic RfD.
  • There are no chemicals with new toxicity values due to Cal EPA updates.
  • The following chemicals have been identified as carcinogenic by a mutagenic mode of action:

  • Based on updates to the 2021 EPA memo “Recommendations on the use of Chronic or Subchronic Noncancer Values for Superfund Human Health Risk Assessments”:

    • The ATSDR chronic RfC will be used instead of the IRIS chronic RfC for 1,1-Dichloroethylene.
    • The ATSDR subchronic RfC will be used instead of the IRIS chronic RfC for Vinyl chloride.
    • The ATSDR subchronic RfD will be used instead of the IRIS chronic RfD for gamma-Hexachlorocyclohexane (lindane).
  • Elemental phosphorus was added to the RSLs with the generic CAS of 7723-14-0. Previously that CAS was assigned to white phosphorus. White phosphorus is now assigned the specific CAS of 12185-10-3. The toxicity values, vapor pressure, and Henry's Law constant from IRIS and ATSDR have been assigned to both phosphorus and white phosphorus. Phosphorus (7723-14-0) is linked to elemental phosphorus (P), red phosphorus, and black phosphorus. White phosphorus (12185-10-3) is an allotrope of elemental phosphorus (P4), sometimes called yellow phosphorus.
  • The lead action level was updated from 15 to 10  µg/L as outlined in this fact sheet. This action level is presented in the RSL tables in the tap water and MCL columns. Section 5.2 of the user's guide has been updated accordingly.
  • FQs 16, 40, and 56 were edited.
  • User's Guide sections 2.3 bullet 4, 2.4.1 bullet 8, 5.6, 5.17, and 5.29 were edited. Section 5.30 about white phosphorus was added.

May 14, 2024

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • 1-Methylnaphthalene has a new screening chronic and subchronic RfD, chronic and subchronic RfC, and screening oral slope factor.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Acrylonitrile has a new DRAFT subchronic and chronic RfD and subchronic RfC.
    • Chloroform has a new DRAFT subchronic RfD and subchronic and chronic RfC.
    • 1,2-Dichloroethylene, trans- has a new DRAFT subchronic RfD. The subchronic RfC was archived.
    • Hexachlorocyclohexane, alpha- has a new FINAL subchronic and chronic RfD.
    • Hexachlorocyclohexane, beta- has a new FINAL subchronic RfD.
    • Hexachlorocyclohexane, gamma- has a new FINAL subchronic RfD.
    • Nickel Soluble Salts has a new DRAFT subchronic and chronic RfC.
    • Nitrobenzene has a new FINAL subchronic RfD and subchronic RfC.
    • Vinyl Acetate has a new DRAFT subchronic RfC.
    • Vinyl Chloride has a new FINAL subchronic RfC.
  • Chemicals with new toxicity values due to EPA Office of Water updates are:
    • Perfluorooctanoic acid (PFOA) has a new subchronic and chronic RfD and oral slope factor.
    • Perfluorooctanoate has a new subchronic and chronic RfD and oral slope factor.
    • Ammonium perfluorooctanoate has a new subchronic and chronic RfD and oral slope factor.
    • Perfluorooctanesulfonic acid (PFOS) has a new subchronic and chronic RfD and oral slope factor.
    • Perfluorooctanesulfonate has a new subchronic and chronic RfD and oral slope factor.
    • Potassium perfluorooctanesulfonate has a new subchronic and chronic RfD and oral slope factor.
  • Chemicals with new toxicity values due to Cal EPA updates are:
    • Benzene, Trimethyl (Generic Trimethylbenzene) has a new chronic RfC.
    • An incorrect inhalation unit risk for 3,3’-Dimethylbenzidine was removed.

  • Other changes:

    • The following polycyclic aromatic hydrocarbons had parentheses changed to brackets:

      • benzo[e]pyrene.

      • benzo[j]fluoroanthene.

      • dibenzo[a,e]pyrene.

      • dimethylbenzene[a]anthracene, 7,12-.

    • Nitroso-di-N-butylamine, N- was changed to Nitrosodibutylamine, N-.

    • Nitroso-di-N-propylamine, N- was changed to Nitrosodipropylamine, N-.

    • The acronym for perfluorotetradecanoic acid was corrected to be PFTetDA.

    • The acronym for perfluorotridecanoic acid was corrected to be PFTriDA.

    • Propanoate, 3-[3-[2-carboxyethyl(1,1,2,2,3,3,4,4,4-nonafluorobutylsulfonyl)amino]propyl-dimethyl-ammonio] was corrected to remove the incorrect “?” in the chemical name.

    • Bifenazate degradate [1,1'-Biphenyl]-3,4-diol (D9472) was corrected to remove the incorrect “?” in the chemical name.

    • Bifenazate degradate 2-[4-methoxy(1,1'-biphenyl)-3-yl],1-methylethyl ester (D3598) was corrected to remove the incorrect “?” in the chemical name.

    • Sulfoxaflor was corrected to remove the incorrect “?” in the chemical name.

    • Sulfoxaflor degradate- N-(methyl(oxido){1-[6-(trifluoromethyl) pyridin-3-yl]ethyl}-lambda4-sulfanylidene) urea was corrected to remove the incorrect “?” in the chemical name.

  • The residential soil screening level for lead is now 200 mg/kg. If other sources of lead are present, the screening level is 100 mg/kg. Details are available at the Updated Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities website.
  • MCLs were added for perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), hexafluoropropylene oxide dimer (HFPO-DA), perfluorononanoic acid (PFNA), and perfluorobutanesulfonic acid (PFBS). The MCLs are associated with any form of these six PFAS (acid, ion, or salt) but are listed in the Federal Register Notice with the ion forms of these PFAS. However, for the May 2024 RSL tables, the MCLs are associated with the acid forms of these PFAS. For the November 2024 update, the MCLs will be added to the ion forms of these PFAS in the RSL tables to be consistent with the MCLs, but they will remain with the acid forms as well for ease of use for RSL users.
  • FQs 16, 21, and 30 were edited. FQ 34 was added and subsequent FQs were renumbered.
  • The links in User's Guide section 6 were updated.
  • Section 5.29 was added to the User's Guide describing the inclusion of asbestos in the RSLs.

February 28, 2024

  • EPA is recommending a residential soil lead (Pb) screening value of 200 ppm; however, an RSL of 100 ppm should be used if an additional source of lead is identified, such as lead service lines, lead-based paint, or non-attainment areas where the air lead concentrations exceed the National Ambient Air Quality Standards NAAQS. The RSL for lead in residential soil will be updated in the Tables following the May 2024 updates. For more information: Updated Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities | US EPA
  • EPA is recommending a residential soil lead (Pb) RML value of 200 ppm based on the most recent science demonstrating adverse impacts of lead exposure at low blood lead levels. RMLs are typically expected to be associated with a level of risk that is likely to warrant removal action. The RML for lead in residential soil will be updated in the Tables following the May 2024 updates. For more information: Updated Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities | US EPA

November 8, 2023

  • The resident tap water THQ=1.0 PDF table has been replaced correcting the name of Bis(trifluoromethylsulfonyl)amine (TFSI). No RSLs have changed.

November 7, 2023

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:

    • Acrylonitrile has lost its subchronic and chronic RfD (the profile is now DRAFT), so HEAST values will now be used,

    • Beryllium has lost its subchronic RfC (the value was ARCHIVED),

    • 1,2-Dichloroethene, trans has lost its subchronic RfD (the profile is now DRAFT),

    • 1,2,3,6,7,8-Hexachlorodibenzofuran has a new FINAL subchronic RfD,

    • Methyl tert-Butyl Ether (MTBE) has a new FINAL subchronic RfC and subchronic RfD,

    • Nickel has lost its subchronic and chronic RfC (the profile is now DRAFT); the chronic RfC will be replaced by CalEPA,

    • 1,2,3,7,8-Pentachlorodibenzofuran has a new FINAL subchronic RfD,

    • 2,3,4,7,8-Pentachlorodibenzofuran has a new FINAL subchronic and chronic RfD, and

    • Vinyl Acetate has lost its subchronic RfC (the profile is now DRAFT), so the HEAST value will now be used.

  • Chemicals with new toxicity values due to PPRTV updates are:

    • Aluminum salts of inorganic phosphates has a new screening chronic and subchronic RfD,

    • Aluminum metaphosphate has a new screening chronic and subchronic RfD,

    • Monoaluminum phosphate has a new screening chronic and subchronic RfD,

    • Phosphoric acid, aluminum salt (1:1) [aluminum phosphate] has a new screening chronic and subchronic RfD,

    • Phosphoric acid, aluminum sodium salt (1:X:X) [sodium aluminum phosphate acidic (acidic SALP)] has a new screening chronic and subchronic RfD,

    • Sodium aluminum phosphate (anhydrous) has a new screening chronic and subchronic RfD,Sodium aluminum phosphate (tetrahydrate) has a new screening chronic and subchronic RfD,

    • Trialuminum sodium tetra decahydrogenoctaorthophosphate (dihydrate) has a new screening chronic and subchronic RfD,

    • Triphosphoric acid, aluminum salt (1:1) [aluminum triphosphate] has a new screening chronic and subchronic RfD,

    • Fluorene has a new subchronic RfD, and

    • Methylcyclohexane has a new screening subchronic RfD and screening chronic RfC.

  • Chemicals with new toxicity values due to Cal EPA updates are:
    • Chromium III (Soluble Compounds) has a new chronic RfC.
  • EPA’s HERA program has posted the final Office of Research and Development (ORD) Human Health Toxicity Values for Perfluoropropanoic Acid (PFPrA), Lithium bis[(trifluoromethyl)sulfonyl]azanide (HQ-115), and Trifluoro-N-(trifluoromethanesulfonyl)methanesulfonamide, 1,1,1- (TFSI) . These toxicity assessments provide actionable science to inform EPA decision contexts and were developed in response to a request for site-specific technical support. Please see U.S. EPA. ORD Human Health Toxicity Value for Perfluoropropanoic Acid and U.S. EPA. ORD Human Health Toxicity Value for Lithium bis [(trifluoromethyl)sulfonyl]azanide for more information. These new chemicals have chronic RfDs.
  • The 11th Cycle of Groundwater Standards Proposals from the State of Wisconsin Department of Health Services includes recommended standards for 4 PFAS chemicals (Perfluoroundecanoic acid (PFUDA), Perfluorododecanoic acid (PFDoDA), Perfluorotetradecanoic acid (PFTetA), and Perfluorooctadecanoic (PFODA)) as well as other chemicals. The EPA Office of Land and Emergency Management’s (OLEM) Human Health Regional Risk Assessment Forum’s (OHHRRAF) Toxicity Workgroup recommends using these values because toxicity values from the other sources do not exist. While the recommended state (Wisconsin) reference values were derived by a state whose toxicity values have not been used before, the state’s toxicity information was determined by the OHHRRAF’s Toxicity Workgroup to be based on similar methods and procedures as those used for other Tier 3 values. These new chemicals have chronic RfDs.
  • Chemical name changes:
    • Sodium Acid Pyrophosphate is now Sodium pyrophosphate,
    • DDD, p,p'- (DDD) is now Dichlorodiphenyldichloroethane, p,p'- (DDD)
    • DDE, p,p'- (DDE) is now Dichlorodiphenyldichloroethylene, p,p'- (DDE)
    • DDT is now Dichlorodiphenyltrichloroethane, p,p'- (DDT)
    • JP-7 is now Jet propulsion fuel 7 (JP-7)
    • TCMTB is now Thiocyanic acid, (2-benzothiazolylthio)methyl ester (TCMTB)
  • Notable changes to chemical-specific parameters are:
    • Due to the growing number of PFAS in the RSL tables, for this update a concerted effort was made to populate the missing chemical-specific parameters in our database and revisit existing parameters to promote consistency. Specifically, it was decided that for boiling point, melting point, vapor pressure, and water solubility data gaps in the ion form could use surrogate values from the acid form. Data gaps in parameters for the salt forms were not given surrogate values from the acid forms. For every PFAS in the RSLs the acid, ion, and salts were grouped and their parameters were visually analyzed for consistency.
  • The calculator, in site-specific mode for the construction worker land use, now returns the higher value of the mass-limit subchronic volatilization factor (VFmlim-sc) and the unlimited subchronic volatilization factor ( VFulim-sc) when the mass limit VF option is selected.
  • The calculator, in site-specific mode for the soil to groundwater land use, now returns the higher value of the mass limit-based RSL (method 2) and the partition model-based RSL (method 1) when the mass limit option is selected.
  • The recreator land use defaults for soil ingestion and skin surface area were removed. The values were identical to the resident. The body weights and exposure durations of the resident will remain in the calculator for use in the recreator scenario for soil/sediment and surface water. For surface water, the surface area of the resident will remain for use in the recreator scenario and the incidental ingestion of surface water intake rates will remain as they are specific to swimming from the Exposure Factors Handbook.
  • The homepage and user's guide text has been updated to clarify that the RSLs are to be used as screening levels and not preliminary remediation goals.

May 4, 2023

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • Chemicals with new toxicity values due to IRIS updates are:
    • Ammonium perfluorobutanoate has a new chronic and subchronic RfD,
    • Ammonium perfluorohexanoate has a new chronic and subchronic RfD,
    • Perfluorobutanoate has a new chronic and subchronic RfD,
    • Perfluorobutanoic acid (PFBA) has a new chronic and subchronic RfD,
    • Perfluorohexanoate has a new chronic and subchronic RfD,
    • Perfluorohexanoic acid (PFHxA) has a new chronic and subchronic RfD,
    • Potassium heptafluorobutanoate has a new chronic and subchronic RfD,
    • Sodium perfluorobutanoate has a new chronic and subchronic RfD, and
    • Sodium perfluorohexanoate has a new chronic and subchronic RfD.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Alpha hexachlorocyclohexane has lost its chronic and subchronic RfD (The profile is now DRAFT),
    • Beta hexachlorocyclohexane has lost its subchronic RfD (The profile is now DRAFT),
    • Gamma hexachlorocyclohexane (Lindane) has lost its subchronic RfD (The profile is now DRAFT), which was more protective that the IRIS chronic RfD value that will now be used, and
    • Vinyl chloride has lost its subchronic RfC (The profile is now DRAFT), which was more protective that the IRIS chronic RfC value that will now be used.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Isobutyl alcohol has a new chronic and subchronic screening RfC,
    • Phosphoric acid has a new chronic and subchronic RfD,
    • Polyphosphoric acid has a new chronic and subchronic RfD,
    • Perylene has a new screening chronic and subchronic RfD and RfC,
    • Dipotassium phosphate has a new chronic and subchronic RfD,
    • Disodium phosphate has a new chronic and subchronic RfD,
    • Monopotassium phosphate has a new chronic and subchronic RfD,
    • Monosodium phosphate has a new chronic and subchronic RfD,
    • Potassium salts of inorganic phosphates has a new chronic and subchronic RfD,
    • Potassium tripolyphosphate has a new chronic and subchronic RfD,
    • Sodium acid pyrophosphate has a new chronic and subchronic RfD,
    • Sodium Hexametaphosphate has a new chronic and subchronic RfD,
    • Sodium polyphosphate has a new chronic and subchronic RfD,
    • Sodium salts of inorganic phosphates has a new chronic and subchronic RfD,
    • Sodium trimetaphosphate has a new chronic and subchronic RfD,
    • Sodium tripolyphosphate has a new chronic and subchronic RfD,
    • Tetrapotassium phosphate has a new chronic and subchronic RfD,
    • Tetrasodium pyrophosphate has a new chronic and subchronic RfD,
    • Tripotassium phosphate has a new chronic and subchronic RfD, and
    • Trisodium phosphate has a new chronic and subchronic RfD.
  • Chemicals with new toxicity values due to Cal EPA updates are:
    • Bromate has a new inhalation unit risk,
    • Calcium cyanide has a new chronic RfC,
    • 3,3'-Dimethoxybenzidine has a new inhalation unit risk,
    • Potassium cyanide has a new chronic RfC,
    • Sodium cyanide has a new chronic RfC,
    • Sodium fluoride has an updated chronic RfC,
    • 1-Bromopropane has a new inhalation unit risk,
    • Bromoacetic acid has a new chronic RfD,
    • Chloroacetic acid has a new chronic RfD, and
    • Dibromoacetic acid has a new chronic RfD and oral slope factor
  • 2-Chloro-1,3-butadiene was changed to 2-Chloro-1,3-butadiene (chloroprene).
  • Notable changes to chemical-specific parameters are:
    • Cyclohexene, a component of the TPH aliphatic low fraction, has multiple new parameters.
    • TPH aliphatic low fraction has multiple new parameters due to the Cyclohexene update.
    • Perfluorooctanesulfonic acid (PFOS), Potassium perfluorobutanesulfonate, Potassium perfluorooctanesulfonate, and Perfluorohexanesulfonic acid (PHFxS) have multiple new parameters from new sources.
  • The threshold criteria for reporting differences in RSLs from one update to the next in the summary table compare files has changed to capture smaller differences. The absolute difference is still calculated, but only changes that are greater than 1% are reported.
  • The introductory paragraphs in sections 2.3.5 and 2.3.6 of the user's guide have been updated to clarify the use of TEFs and RPFs in the RSLs.

November 18, 2022

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Acetone subchronic RfD has been added,
    • Aldrin chronic RfD has been added,
    • 2-Chlorophenol subchronic RfD has been added,
    • 4-Chlorophenol subchronic RfD has been added,
    • Copper subchronic RfD has been dropped because the assessment is now draft,
    • DDD,p,p’ subchronic and chronic RfD have been added,
    • DDE,p,p’ subchronic and chronic RfD have been added,
    • DDT,p,p’ subchronic and chronic RfD have been added,
    • 1,1-Dichloroethene subchronic and chronic RfC and chronic RfD have been added,
    • 2,4-Dichlorophenol subchronic RfD has been added,
    • Dieldrin subchronic and chronic RfD have been added,
    • Disulfoton subchronic RfC and subchronic and chronic RfD have been added,
    • Ethylene Oxide subchronic RfC has been added,
    • Mercuric chloride subchronic RfD has been dropped because the assessment is now draft,
    • Mercury chronic RfC has been dropped because the assessment is now draft,
    • Methylmercury chronic RfD has been dropped because the assessment is now draft,
    • Pentachlorophenol chronic RfD has been added,
    • 2,3,4,6-Tetrachlorophenol subchronic RfD has been added,
    • 2,4,5-Trichlorophenol subchronic RfD has been added, and
    • 2,4,6-Trichlorophenol subchronic RfD has been added.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Total Petroleum Hydrocarbons Aliphatic Low has new chronic and subchronic RfDs and RfCs and a new screening inhalation unit risk,
    • Total Petroleum Hydrocarbons Aromatic Low has dropped all RfDs and RfCs,
    • Total Petroleum Hydrocarbons Aromatic Medium has new chronic and subchronic RfDs and RfCs,
    • Total Petroleum Hydrocarbons Aromatic High has new chronic and subchronic RfDs and RfCs and new oral slope factor and inhalation unit risk,
    • cis-1,2-dichloroethylene has new screening chronic and subchronic RfCs and a new subchronic RfD, and
    • dibenzothiophene has a new screening subchronic RfD and the chronic screening RfD was dropped.
  • Chemicals with new toxicity values due to Cal EPA updates are:
    • Chromium III has new chronic and subchronic RfCs,
  • There are no chemicals with new toxicity values due to EPA Office of Water updates.
  • There are no chemicals with new toxicity values due to OPP updates, however the toxicity metadata has been added for all chemicals from this source.
  • Section 1 of the User's Guide was updated to clarify how RSLs can be used as PRGs.
  • Section 5.11 of the User's Guide, and the corresponding FAQ, were updated to present the new carbon ranges for the Total Petroleum Hydrocarbons and the new representative compounds. Of particular interest, the aromatic medium fraction is no longer represented by a PAH and therefore no longer has an ABS. While the RSLs do not address carcinogenicity for TPHs, the aromatic high fraction is now considered a mutagen based on benzo[a]pyrene.
  • Section 6 of the User's Guide was updated to shorten the variable description table provided in html. The entire table is provided in a spreadsheet and a PDF file.
  • The calculator page has new tool tips that can be accessed by hovering over the blue question marks.
  • The soil adherence factor values for the recreator were removed. The values were identical to the resident. The Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance  for Dermal Risk Assessment) provides recreational soil adherence factors for many activities.

May 18, 2022

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Perfluorohexanesulfonate has a new subchronic RfD that will be used as a chronic RfD,
    • Perfluorohexanesulfonic acid (PFHxS) has a new subchronic RfD that will be used as a chronic RfD,
    • Perfluorononanoate has a new subchronic RfD that will be used as a chronic RfD,
    • Perfluorononanoic acid (PFNA) has a new subchronic RfD that will be used as a chronic RfD,
    • Perfluorooctanesulfonate has a new subchronic RfD that will be used as a chronic RfD,
    • Perfluorooctanesulfonic acid (PFOS) has a new subchronic RfD that will be used as a chronic RfD,
    • Potassium perfluorooctanesulfonate has a new subchronic RfD that will be used as a chronic RfD,
    • Perfluorooctanoate has a new subchronic RfD that will be used as a chronic RfD, and
    • Perfluorooctanoic acid (PFOA) has a new subchronic RfD that will be used as a chronic RfD.
  • There are no chemicals with new toxicity values due to PPRTV updates.
  • There are no chemicals with toxicity changes due to Cal EPA updates.
  • Chemicals with toxicity changes due to EPA Office of Water updates are:
    • Hexafluoropropylene oxide dimer acid (HFPO-DA, sometimes called GenX) has a new chronic and subchronic RfD, and
    • Hexafluoropropylene oxide dimer acid ammonium salt (Ammonium perfluoro-2-methyl-3-oxahexanoate) has a new chronic and subchronic RfD.
  • Section 2.3 of the User's Guide was updated to accommodate the EPA Office of Water PFAS toxicity values.
  • There are no chemicals with new toxicity values due to OPP updates.
  • Section 4.8.6 was added to the User's Guide highlighting the conservative and simplifying assumptions for the soil to groundwater scenario.
  • Section 5.15 of the User's Guide was edited to remove the discussion about using RSLs to calculate risk and hazard index for multiple contaminants.
  • The programming of the infinite source volatilization factors (VFulim and VFulim-sc) were changed to allow the calculation of the VF when H' is missing, similar to the soil to groundwater and Csat models.

November 17, 2021

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • Chemicals with new toxicity values due to IRIS updates are:
    • Ethyl Tertiary Butyl Ether (ETBE) has new chronic oral noncancer, chronic inhalation noncancer, and inhalation cancer, and
    • tert-Butyl Alcohol (tBA) has a new chronic RfD, chronic RfC, and oral slope factor.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Acetone chronic RfC was dropped.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Ammonium Salts of Inorganic Phosphates has a new screening subchronic RfD,
    • Benzo(e)pyrene has new screening chronic and subchronic RfDs and RfCs,
    • Bromo-2-chloroethane, 1- has new screening chronic and subchronic RfDs and RfCs,
    • Calcium Salts of Inorganic Phosphates has a new screening subchronic RfD,
    • Dinitroaniline, 3,5- has new screening chronic and subchronic RfDs and RfCs,
    • Toluenediamine, 2,3- has new screening chronic and subchronic RfDs,
    • Toluenediamine, 3,4- has new screening chronic and subchronic RfDs, and
    • Pentaerythritol Tetranitrate (PETN) has new chronic and subchronic RfDs and screening oral slope factor.
  • Chemicals with toxicity changes due to Cal EPA updates are:
    • Nickel refinery-dust oral cancer removed,
    • Nickel acetate oral cancer removed,
    • Nickel carbonate oral cancer removed,
    • Nickel hydroxide oral cancer removed,
    • Nickel carbonyl oral cancer removed, and
    • Nickel oxide oral cancer removed,
  • Chemicals with new toxicity values due to OPP updates are:
    • Acephate has a new chronic RfD,
    • Chlorpropham has a new chronic RfD,
    • Cyhalothrin chronic RfD was dropped,
    • Cypermethrin chronic RfD was added,
    • Butanoic acid, 4-(2,4-dichlorophenoxy)- chronic RfD was dropped,
    • Fomesafen chronic RfD was updated,
    • Oxyfluorfen chronic RfD was updated,
    • Imazalil chronic RfD was updated,
    • Norflurazon chronic RfD was updated,
    • Oryzalin chronic RfD was updated,
    • Pirimiphos, Methyl chronic RfD was updated, and
    • Thiophanate, Methyl chronic RfD was updated.
  • Several subchronic toxicity values were programmed to be used in place of chronic toxicity values. The memo directing this substitution is available here. This action was necessitated because several subchronic values were more protective than the chronic values.
  • The inorganic phosphate PPRTVs were retired, pending updates. The new PPRTVs for ammonium and calcium phosphates only provided subchronic values. As a result, the entire chemical group, "Phosphates, Inorganic" was eliminated from the new screening tables.
  • A new chemical group was added to the tables, "Per- and Polyfluoroalkyl Substances (PFAS)". Perfluorobutanesulfonate, Perfluorobutanesulfonic acid (PFBS), and Potassium Perfluorobutane Sulfonate appear under this heading.
  • The calculator, in site-specific mode for the mass-limit volatilization factor (VF) option, now returns the higher value of the mass-limit and the standard VF calculation method.
  • FAQ 51 and User's Guide section 5.11 was updated to clarify the application of TPH carbon rages to DRO, GRO, ORO, RRO and other carbon range data that may not exactly match the carbon ranges in the RSLs.

May 11, 2021

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • There are no chemicals with new toxicity values due to ATSDR updates.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Perfluorobutanesulfonic acid (PFBS) oral noncancer,
    • Perfluorobutanesulfonate oral noncancer, and
    • Potassium perfluorobutane sulfonate oral noncancer.
  • There are no chemicals with new toxicity values due to Cal EPA updates.
  • Cypermethrin has oral noncancer toxicity values due to OPP updates. Cypermethrin was adventitiously removed from the RSLs in 2018.
  • CRC Handbook of Chemistry and Physics vapor pressure values were added to the hierarchy. Section 2.4 of the User's Guide was updated accordingly.
  • The discussion of relative bioavailability (RBA) for arsenic in soils was updated to include sediment. See section 5.10 of the User's Guide for details.
  • Cadmium and Manganese air RSLs are now shown in both table rows.
  • User's Guide Section 2.3, bullet 3, was updated with new links to the 51 pesticides retired by IRIS in 2017.
  • Section 4.9.8 of the User’s Guide was updated to provide more descriptive text of the methods used to determine the EPD, FA, and Kp parameters as originally described in RAGS Part E. Additionally, new equations were added that replaced the programming language that was used previously to explain the methods.
  • Technical chlordane oral noncancer toxicity values are used as surrogates for alpha (cis) and gamma (trans) chlordanes. See section 5.28 of the User's Guide for details.

November 18, 2020

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Molybdenum inhalation noncancer.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Glycidaldehyde inhalation noncancer.
    • trans-1,2-dichloroethylene inhalation noncancer.
    • p-phthalic acid oral noncancer.
    • picric acid oral noncancer.
    • Vinyl bromide inhalation cancer.
    • Ammonium picrate oral noncancer (new chemical).
    • Midrange aliphatic hydrocarbon streams oral and inhalation noncancer and inhalation cancer. (The 2009 PPRTV is not new, but the toxicity values have been added to the RSLs.)
    • Pentamethylphosphoramide (PMPA) oral noncancer (new chemical).
    • N,N,N',N"-tetramethylphosphoramide (TMPA) oral noncancer (new chemical).
  • Chemicals with new toxicity values due to Cal EPA updates:
    • 4-chlorobenzotrifluoride inhalation cancer.
  • There are no chemicals with new toxicity values due to OPP updates.
  • The chemical name glycidyl was changed to glycidaldehyde.
  • The naming conventions for cis and trans-1,2-dichloroethylene were slightly altered to dichloroethylene, cis-1,2- and dichloroethylene, trans-1,2- from dichloroethylene, 1,2-cis- and dichloroethylene, 1,2-trans-, respectively.
  • The "p" for "para" in p-phthalic acid was changed to a lower case.
  • The chemical name mephos oxide was changed to tribufos.
  • The CASRN for diquat was changed to 2764-72-9 from 85-00-7 and chemical-specific parameters were updated, accordingly.
  • Commercial hexane was given an EPA ID of E5241997.
  • Midrange aliphatic hydrocarbon streams was given an EPA ID of E1790669.
  • User's Guide section 5.8 about PCBs and Aroclors was updated to include more detailed information on the selection of toxicity values.
  • Ammonium picrate and picric acid were given the same chemical-specific parameters because ammonium picrate dissolves very readily to picric acid.
  • Midrange aliphatic hydrocarbon streams was given the same chemical-specific parameters as n-nonane.

May 21, 2020

The tables released on May 18, 2020 mistakenly applied the oral slope factor for nickel refinery dust to nickel soluble salts. This mistake has been corrected. All affected tables have been replaced with corrected tables. This includes the tables presented on the Generic Tables page and also the changes and comparison tables linked below in the May 18, 2020 update section. Corrected tables have (corrected) in the header. The residential and commercial air tables, chemical parameter tables, and subchronic tables were not affected.

May 18, 2020

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Antimony inhalation noncancer.
  • Chemicals with new toxicity values due to PPRTV updates are: 
    • commercial hexane inhalation noncancer and cancer. (The 2009 PPRTV is not new, but the toxicity values have been added to the RSLs.)
    • 2-amino-4,6-dinitrotoluene screening oral noncancer.
    • 4-amino-2,6-dinitrotoluene screening oral noncancer.
  • Chemicals with new toxicity values due to Cal EPA updates:
    • Chlorothalonil oral cancer was added and inhalation cancer was removed.
    • Direct black 38 inhalation and oral cancer updated.
    • Direct blue 6 inhalation cancer updated.
    • Direct brown 95 inhalation cancer updated.
    • 2-methoxy-5-nitroanaline inhalation cancer removed.
    • Naphthalene oral cancer added.
    • Lead acetate oral cancer and inhalation cancer updated.
    • Lead subacetate oral cancer and inhalation cancer updated.
    • Nickel acetate oral cancer added.
    • Nickel carbonate oral cancer added.
    • Nickel hydroxide oral cancer added.
    • Nickelocene oral cancer added.
    • Nickel carbonyl oral cancer added.
    • Nickel oxide oral cancer added.
    • Nickel refinery dust oral cancer added. (On the originally released May 18, 2020 tables, the nickel refinery dust oral slope factor was mistakenly applied to nickel soluble salts. This has been fixed on the corrected tables.) 
    • Hexamethylene diisocyanate biuret inhalation noncancer (new chemical).
    • Hexamethylene diisocyanate isocyanurate inhalation noncancer new chemical).
  • There are no chemicals with new toxicity values due to OPP updates.
  • Chlordane was changed to Chlordane (technical mixture), but the toxicity values have not changed.
  • The CAS for coke oven emissions was removed and replaced with an EPA ID.
  • A new CAS was given for polybrominated biphenyls.
  • The nonchlorinated furans (furan, dibenzofuran, and tetrahydrofuran) mistakenly applied the ABSd for chlorinated dioxins and dioxin like compounds (0.03). The ABSd was removed because the three furans in question are volatiles.
  • FQ 16 was added to discuss how to address detection limits that are higher than RSLs and handling of nondetects. Subsequent FAQs were renumbered.
  • FQ 33 about PPRTV Appendix Screening values was updated to clarify the derivation process.
  • FQ 51 and User's Guide section 5.11 about TPH surrogates were updated as were some chemical parameters for the TPH fractions.
  • User's Guide section 5.7 was updated concerning the aminodintrotoluenes. The new PPRTV values have replaced the IRIS surrogate.

November 18, 2019

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • The RSL and RML default values are available in the Apple Store and the Google Play Store for use on mobile devices. Please note that the app currently has the May 2019 data in it. We anticipate updating the app data with November 2019 data the first week of December. 
  • There are no chemicals with new toxicity values due to IRIS updates.
  • There are no chemicals with new toxicity values due to ATSDR updates.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Nitropropane, 2- an appendix screening value inhalation unit risk was added.
    • Tetrachlorotoluene, p- alpha, alpha, alpha- appendix screening values were added for oral noncancer and oral cancer.
  • There are no chemicals with new toxicity values due to Cal EPA updates.
  • There are no chemicals with new toxicity values due to OPP updates.
  • Uranium (soluble salts) was renamed Uranium with CAS 7440-61-1.
  • Chloramines, organic was assigned EPA ID E701235.
  • Xylene, P- was renamed Xylene, p-.
  • Hexachlorodibenzo-p-dioxin, Mixture was given the CAS 34465-46-8.
  • Molecular weights for Aroclors 1016, 1248, and 5460 were updated to 257.55, 291.99, and 540.3 g/mol, respectively.
  • The ABS values for TPH aromatic medium and high were updated to match their surrogates (0.13 for both).
  • Dermal permeability values (Kp) were updated for six chemicals.
  • The recreator incidental ingestion of surface water intake rates were updated to 0.124 L/hr and 0.0985 L/hr for the 6-16 year and 16-26 year age bins, respectively. Equations and references have been updated.
  • Section 2.4.1 of the User's Guide was updated to include item 17 describing how critical temperature, enthalpy of vaporization at the normal boiling point, and  lower explosive level values were referenced from OSWER Publication 9200.2-154 and associated calculation spreadsheet (VISL).
  • Section 2.4.2 of the User's Guide was updated to include VISL in the hierarchies for critical temperature, enthalpy of vaporization at the normal boiling point, and  lower explosive level.
  • Section 2.5 of the User's Guide was updated to provide link to 2018 Edition of the Drinking Water Standards and Health Advisories.
  • Section 4.8 of the User's Guide was updated to present the newly assigned CAS numbers.
  • Section 5.26 was added to the User's Guide describing the derivation of the perchlorate screening level in tap water.
  • Section 5.27 was added to the User's Guide describing the styrene-acrylonitrile trimer (SAN Trimer) chromatography results of the isomers and how that affects risk calculations.
  • FQ 29 was updated to include a link to a units conversion calculator to assist converting ppb to µg/m3 and other units.

May 16, 2019

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with new toxicity values due to IRIS updates.
  • There are no chemicals with new toxicity values due to ATSDR updates.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Hexanol, 1-,2-ethyl- (2-Ethyl-1-hexanol) oral cancer, oral noncancer, and inhalation noncancer values were added.
    • Styrene-Acrylonitrile (SAN) Trimer (THNP isomer) oral noncancer value was added.
    • Endosulfan Sulfate oral noncancer value was added.
  • Chemicals with toxicity value changes due to Cal EPA updates are:
    • Formaldehyde has a new oral slope factor.
    • Toluene-2,6-diisocyanate has a new oral slope factor.
    • Toluene-2,4-diisocyanate has a new oral slope factor.
    • Butadiene, 1,3- has an updated oral slope factor.
  • There are no chemicals with new toxicity values due to OPP updates.
    • Thiophanate, Methyl oral noncancer value from OPP was corrected to match rounded value found in OPP documentation.
  • Styrene-Acrylonitrile (SAN) Trimer was renamed Styrene-Acrylonitrile (SAN) Trimer (THNA isomer).
  • The Generic Table and Calculator result key definitions have been simplified.
  • Users can now enter their own PEF values for all land uses.
  • FQ 50 and User's Guide section 5.11 were updated to clarify the RfD, RfC, and chemical-specific parameter surrogate compounds for the TPHs.
  • FQ 15 and User's Guide sections 4.9.9 and 4.9.4 have been added to explain how a chemical's volatility status is impacted when the groundwater-soil system temperature is changed. 
  • FQ 41 and User's Guide section 5.25 have been added to explain how to apply the trihalomethane and haloacetic acid MCLs.
  • User's Guide section 2.5 was updated to explain the inclusion of MRDLs as MCLs.
  • User's Guide section 3 was updated to include discussion of tables with a target hazard quotient of 0.1.
  • In the past, inorganic compounds were not permitted to be classified as volatile (except for mercury). To address this restriction, the RSL programming for the soil to groundwater land use set all H' values to zero for inorganics. This restriction has been lifted. Now all volatiles regardless of being organic or inorganic are modeled in the soil to groundwater land use.
  • The chemical names for nitrate and nitrite have been changed to "nitrate (measured as nitrogen)" and "nitrite (measured as nitrogen)".
  • The refractory ceramic fiber values presented in the previous RSL version were based on an RfC of fibers/cm3. This version presents the RfC units in terms of fibers/m3 to be consistent with the other chemicals in terms of volume in the denominator. The explanation and equations in User's Guide section 5.23 have been modified.

November 19, 2018

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • Chemicals with toxicity value changes due to IRIS updates are:
    • Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has a new IRIS profile with an updated oral chronic reference dose and oral slope factor.
  • There are no chemicals with new toxicity values due to ATSDR updates.
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Toxaphene, technical chronic and subchronic RfD assessments were added.
    • Toxaphene, weathered chronic and subchronic RfD appendix screening values were added.
    • Lutetium subchronic RfD was added.
    • Lanthanum chronic and subchronic RfD assessments were added.
    • Lanthanum chloride, anhydrous chronic and subchronic RfD assessments were added based on the RfD for Lanthanum, after applying molecular weight adjustment and appropriate stoichiometric calculations.
    • Lanthanum chloride heptahydrate chronic and subchronic RfD assessments were added based on the RfD for Lanthanum, after applying molecular weight adjustment and appropriate stoichiometric calculations.
    • Lanthanum nitrate hexahydrate chronic and subchronic RfD assessments were added based on the RfD for Lanthanum, after applying molecular weight adjustment and appropriate stoichiometric calculations.
    • Lanthanum acetate hydrate chronic and subchronic RfD assessments were added based on the RfD for Lanthanum, after applying molecular weight adjustment and appropriate stoichiometric calculations.
  • Tert-butyl acetate oral and inhalation cancer values from Cal EPA were added.
  • There are no chemicals with toxicity changes due to OPP updates.
  • User's Guide section 2.3.5 was updated to include the dioxin congener CAS numbers in the toxicity equivalence factor table. Additionally, HCDD, 1,2,3,4,6,7,8,- is being renamed Heptachlorodibenzo-p-dioxin, 1,2,3,4,6,7,8-, and the TEF of 0.01 will be applied replacing the current toxicity sources. The following non-specified chlorine congeners are being removed from RSL Calculator pick list:
    • 34465-46-8 ; Hexachlorodibenzo-p-dioxin
    • 37871-00-4 ; HpCDD, 2,3,7,8-
    • 36088-22-9 ; PeCDD, 2,3,7,8-
    • 38998-75-3 ; HpCDF, 2,3,7,8-
    • 55684-94-1 ; HxCDF, 2,3,7,8-
  • User's Guide section 2.5 has been updated to describe how MCLs are used in data screening and how they are different than RSLs.
  • User's Guide section 5.24 has been added describing the calculation of RfDs for lanthanum salts via molecular weight adjustment.
  • The Kd for fluoride was applied to sodium fluoride and fluorine (soluble fluoride). The Kd table in User's Guide section 4.8 was updated.
  • New language describing the rationale behind the two different foc values used in RSL equations has been added to User's Guide sections 4.8.3 and 4.9.4.
  • User's Guide section 5.23 has been added describing the calculation of RSLs for refractory ceramic fibers. Soil screening levels have been removed for refractory ceramic fibers, and only air screening levels are calculated now.
  • Phosgene is now activated to give RSLs in tap water.
  • The FQs have been numbered sequentially.
  • The Generic Tables download page now has a table providing descriptions of annotations and abbreviations used in the RSL tables and Calculator output. Short definitions and links to pages with detailed discussion are provided.
  • The key presented in the Generic Tables and Calculator results has been updated.

May 15, 2018

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with toxicity value changes due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • Bromodichloromethane is now a draft. Therefore, the former oral chronic values have been removed.
    • Bromomethane is now a draft. Therefore, the former inhalation chronic and oral intermediate values have been removed.
    • Methelendiphenyl Diisocyanate (MDI) is now final. It has an inhalation chronic value.
    • Toluene Diisocyanate (TDI) is now final. It has inhalation chronic values.
  • There are no chemicals with new toxicity values due to PPRTV updates.
  • Chemicals with toxicity changes in the OPP database are:
    • cypermethrin oral chronic reference dose removed,
    • bromoxynil octanoate gained an oral slope factor,
    • propargite oral slope factor changed,
    • pendimethalin oral chronic reference dose changed,
    • flurprimidol oral chronic reference dose changed,
    • chlorsulfuron oral chronic reference dose changed,
    • cyromazine oral chronic reference dose changed,
    • dicrotophos oral chronic reference dose changed, and
    • pirimiphos, methyl oral chronic reference dose changed.
  • There are no chemicals with toxicity value changes due to Cal EPA updates.
  • The MCL for fluoride has been assigned to fluoride, sodium fluoride, and fluorine (soluble fluoride).
  • Enthalpy of vaporization at the boiling point values have been added from Yaws and the hierarchy in User's Guide 2.4.2 has been updated.
  • Changes have been made to the User's Guide in sections 2.3, 2.4.2, 4.1.1, 4.9.1, 5.4, and 5.10.
  • Changes have been made to FAQs 9, 19, 20, 24, and 26.

November 30, 2017

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • There are no chemicals with toxicity value changes due to IRIS updates.
  • Chemicals with new toxicity values due to ATSDR updates are:
    • bromopropane, 1-,
    • glutaraldehyde,
    • diethyl-meta-toluamide, N,N (DEET) (subchronic only), and
    • nitrate and nitrite (subchronic only).
  • Chemicals with new toxicity values due to PPRTV updates are:
    • DDD, p,p'- (DDD),
    • DDE, p,p'-,
    • lactonitrile,
    • toluic acid, p-,
    • diphenyl ether,
    • methyl-2-pentanol, 4-,
    • heptanal, n-,
    • difluoropropane, 2,2-
    • bromo-4-fluorobenzene, 1-,
    • bromo-3-fluorobenzene, 1-, and
    • tert-butyl formate (subchronic only).
  • The chromates presented by Cal EPA (lead chromate, strontium chromate, barium chromate, sodium dichromate, and calcium chromate) were removed from the RSLs. The oral slope factors and inhalation unit risk factors presented were identical to chromium VI; however, application of the same GIABS for all salts was questionable. It was decided that chromium VI RSLs would be sufficient and if specific forms of chromate were reported from a laboratory, an appropriate GIABS should be derived and applied.
  • The chemical, DDD, was renamed DDD, p,p`- (DDD).
  • bromofluorobenzene, p- was renamed Bromo-4-fluorobenzene, 1-.
  • The dispersion constants for calculation of Q/C for PEF and VF (A, B, and C) for Casper, Wyoming were changed to 17.6482, 18.8138, and 217.039, respectively. In the Supplemental Soil Screening Guidance, Tables D-2 and D-3, as well as E-2 and E-3, contain identical ABC for every city except for Casper, Wyoming. Applying the assertion that Casper was to be the 100 percentile city for PEF and the 0 percentile city for VF, the correct ABC values were deduced.
  • The RSL Calculator now presents the target risk and target hazard quotient on the main page. Additionally, the default target hazard quotient is now 0.1. A new pick list is also provided that contains many synonyms, is also searchable by CAS, and should remember the chemicals selected. When the calculator is run in site-specific mode, users will now have the option to change the system temperature for the VF and soil to groundwater models (see User's Guide section 4.9.9). Changing the temperature will trigger a change in the Henry's Law constant. Changes made in site-specific mode will now be displayed next to the default values in the output table of input parameters.

September 6, 2017

June, 2017

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this (PDF)) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
     
  • uranium (soluble salts) - now uses the ATSDR intermediate MRL based on this memorandum (PDF),
     
  • Chemicals with toxicity value changes due to IRIS updates are:
    • ethylene oxide - has a new IRIS profile, and
    • benzo[a]pyrene and chemicals with associated relative potency factors were updated based on the new IRIS Profile.
    • ammonia,
    • trimethylbenzene, 1,3,5-,
    • trimethylbenzene, 1,2,3-, and
    • trimethylbenzene, 1,2,4-
    • IRIS has archived 51 chemical assessments for pesticides and has recommended the use of the toxicity values presented in the human health benchmarks for pesticides (HHBP) table. Office of Pesticide Program (OPP) lists 363 pesticides in the HHBP table. Only the 51 archived by IRIS will be used in the RSL calculations. The food quality protection factors (FQPA) will be applied to the RfDs, if available. Derivation of the RfDs, for use in RSL calculations, is done by dividing the given RfD by the FQPA to derive a value that is more protective.
       
  • Chemicals with new toxicity values due to ATSDR updates are:
    • hydrogen sulfide and carbonyl sulfide (subchronic only),
    • JP-5, JP-8, and Jet A Fuels (subchronic only),
    • parathion (subchronic only), and
    • polybrominated diphenyl ethers (PBDEs) (subchronic only).
       
  • Chemicals with new toxicity values due to PPRTV updates are:
    • p-chlorobenzenesulfonic acid
    • phenylenediamine, o-,
    • aminophenol, o-,
    • trichloro-1,2,2-trifluoroethane, 1,1,2-,
    • heptane, N-,
    • mercaptobenzothiazole, 2-,
    • rubidium, (subchronic only)
    • tribromophenol, 2,4,6-,
    • rubidium chloride, (subchronic only)
    • rubidium hydroxide, (subchronic only)
    • rubidium iodide, (subchronic only)
    • methylphenol, 3-, (subchronic only)
    • dimethylaniline, N,N-, (subchronic only)
    • phenylenediamine, p-,
    • cyclohexane, 1,2,3,4,5-pentabromo-6-chloro-,
    • dichloropropane, 1,2-,
    • dimethylphthalate, (subchronic only)
    • guanidine nitrate, and
    • phenyl isothiocyanate.
       
  • The TPH chemical property sources were updated to match their representative compounds.
     
  • The RSL tables now include an EPA identification number in the CAS column for those chemicals that did not have a CAS number. "NA" no longer appears. The EPA Identification numbers can be found at the Substance Registry Service (SRS).
     
  • The spelling of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate was corrected.
     
  • Perfluorobutane Sulfonate (PFBS) was changed to Perfluorobutane sulfonic acid (PFBS). Perfluorobutanesulfonate (45187-15-3) was added with same parameters as Perfluorobutane sulfonic acid (PFBS).
  • The programming of the Csat was changed to allow the calculation of the SSL when H' is missing.
     
  • The ingestion rate while swimming was updated based on Table 3.5 in EFH 2011. The recommended values of 120 ml/hr for children and 71 ml/hr for adults are now used.
     
  • Changes have been made to the User's Guide in sections 2.3, 2.3.6, 5.2, 5.5, 5.6, 5.12, 5.14, and 5.21. Section 2.5 has been added describing maximum contaminant levels (MCLs). Section 2.6 has been added describing risk output on the RSL website. A brief description of typical exposures for each land use was added in section 4.
     
  • Changes have been made to FAQ 35 (now 17), 14 (now 41), outdated FAQs were deleted, the FAQs for chromium were combined, and the FAQs were reordered to match the order they were presented.

May, 2016

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf (PDF)) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
     
  • Chemicals with toxicity value changes due to Cal EPA updates are:
    • Lead acetate,
    • Toluene-2,4-diisocyanate, and
    • Toluene-2,6-diisocyanate
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Chloronitrobenzene, p-,
    • Benzaldehyde,
    • Thallic oxide RfD was derived by MW adjustment, and
    • Thallium Selenite RfD was derived by MW adjustment
  • The chemical name associated with CAS 114-26-1 was changed to Phenol, 2-(1-methylethoxy)-, methylcarbamate from Propanediol, 1,2-.
     
  • The programming of the soil to groundwater scenario was changed to allow the calculation of the SSL when H' is missing.
     
  • The programming of the diffusivity in air (Dia) equation was changed to use the dioxin-specific equation for furans and dioxin-like PCBs. See section 4.13.4 of the User's Guide.
     
  • The hierarchy of Koc sources was modified to use the SSL first for the nine ionizable organics identified. See section 2.4.2 of the User's Guide.
     
  • Various parameters have changed for Chlordane, Hydrogen cyanide, Cyanide (CN-) and White phosphorus.
     
  • Freezing point values from Yaws were added to the 6th position of the hierarchy.
     
  • Changes have been made to the User's Guide in sections 2.3, 2.4.2, 4.13.4, 4.13.8, and 5.2.
     
  • Changes have been made to FAQs 5, 21, 28, 29, 41, and 42. FAQ 54 has been added concerning White phosphorus.

January, 2016

  • Toluidine, o- (Methylaniline, 2-) CAS 95-53-4 was added to the calculator pick list. Toxicity values are available from PPRTVs and Cal EPA. Toluidine, o- (Methylaniline, 2-) will appear in the RSL tables in the Spring update.;

November, 2015

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet (XLS) (or this (PDF)) is a comparison of the previous toxicity database to the current. This spreadsheet (XLS) (or this pdf (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet (XLS) (or this (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • Chemicals with toxicity value changes due to Cal EPA updates are:
    • Dibromochloromethane
  • Chemicals with new toxicity values due to PPRTV updates are:
    • Picric Acid (2,4,6-Trinitrophenol),
    • Trimethylpentene, 2,4,4-,
    • Tungsten,
    • Sodium Tungstate,
    • Sodium Tungstate Dihydrate,
    • Ethanol, 2-(2-methoxyethoxy)-,
    • Lewisite,
    • Carbonyl Sulfide, and
    • Trifluoroethane, 1,1,1-.
  • Chemicals from HEAST that have lost toxicity values due to PPRTV updates are:
    • Dibromomethane (Methylene Bromide),
    • Trichlorofluoromethane,
    • Methyl Acrylate,
    • Ethyl Methacrylate,
    • Methyl Isobutyl Ketone (4-methyl-2-pentanone),
    • Bis(2-chloro-1-methylethyl) ether,
    • Hexane, N-,
    • Ethyl Acrylate,
    • Antimony Potassium Tartrate,
    • Propylene Glycol Monoethyl Ether, and
    • Chloroacetic Acid.
  • The RSL workgroup coordinated with the Vapor Intrusion Screening Level (VISL) workgroup to add Physprop has a new source of chemical parameters. Parameters were extracted from Physprop and categorized as experimental or estimated. See section 2.4 for details of Physprop inclusion in the hierarchy.Also SSL was removed as a source for Dia, Diw, MP, HLC, H' and S.
  • Common chemical names were replaced with technical names for the following:
    • Express (101200-48-0) changed to Tribenuron-methyl,
    • Baygon (114-26-1) changed to Phenol, 2-(1-methylethoxy)-, methylcarbamate,
    • Aramite (140-57-8) changed to Sulfurous acid, 2-chloroethyl 2-[4-(1,1-dimethylethyl)phenoxy]-1-methylethyl ester,
    • Bidrin (141-66-2) changed to Dicrotophos,
    • ALAR (1596-84-5) changed to Daminozide,
    • Dacthal (1861-32-1) changed to Chlorthal-dimethyl,
    • Kerb (23950-58-5) changed to Propyzamide,
    • Goal (42874-03-3) changed to Oxyfluorfen,
    • Bayleton (43121-43-3) changed to Triadimefon,
    • Pydrin (51630-58-1) changed to Fenvalerate,
    • Amdro (67485-29-4) changed to Hydramethylnon,
    • Cyhalothrin/karate (68085-85-8) changed to Cyhalothrin,
    • Baythroid (68359-37-5) changed to Cyfluthrin,
    • Apollo (74115-24-5) changed to Clofentezine,
    • Ally (74223-64-6) changed to Metsulfuron-methyl,
    • Assure (76578-14-8) changed to Quizalofop-ethyl,
    • Savey (78587-05-0) changed to Hexythiazox,
    • Harmony (79277-27-3) changed to Thifensulfuron-methyl,
    • Pursuit (81335-77-5) changed to Imazethapyr,
    • Londax (83055-99-6) changed to Bensulfuron methyl,
    • Nustar (85509-19-9) changed to Flusilazole,
    • Guthion (86-50-0) changed to Azinphos-methyl,
    • Systhane (88671-89-0) changed to Myclobutanil, and
    • Benefin (1861-40-1) changed to Benfluralin
  • Melting Point values added the the parameters table.
  • Corrections were posted to the OSWER Directive for child surface area available for water contact. A FAQ has been provided. Items 22 and 23 are the source of the documentation.
  • A FAQ was added to guide users requesting previous versions of tables.
  • The variable names in the equation images and user guide were updated to be consistent with the radionuclide PRG calculator and other similar projects. Also the RBA variable was added to the soil ingestion equation images.

June, 2015 (revised)

  • New Tap Water and Soil to Groundwater Tables were generated that reflect a correction in the tap water cancer inhalation route for:
    • Nitrosodimethylamine, N-
    • Benz[a]anthracene
    • Methylene Chloride
    • Dibromo-3-chloropropane, 1,2.

June, 2015

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet (XLS) (or this (PDF)) is a comparison of the previous toxicity database to the current. This spreadsheet file (XLS) (or this (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.
  • Chemicals with new toxicity values due to new Cal EPA updates are:
    • tris(2,3-dibromopropyl)phosphate
  • The RSL workgroup coordinated with the Vapor Intrusion Screening Level (VISL) workgroup to ensure a consistent approach to volatility. For more information consult the VISL Calculator User's Guide (PDF). The following criteria are now used to define a chemical as volatile in the RSLs: 1) vapor pressure greater than 1 mm Hg or 2) Henry's Law constant greater than 0.00001 atm-m3/mole. There are now over 100 chemicals newly classified as volatile. Chemical-specific parameters were added to the database for use in calculating volatilization factors for the new volatiles.
  • While adopting the new volatility rule, seven chemical type classifications were corrected to distinguish between volatiles and semivolatiles as well as to distinguish between organic and inorganic compounds.
  • The construction worker averaging time for cancer was changed from (50 weeks/yr * 7 days/week) to 365 days per year to be consistent with all the other cancer equations.
  • The F(x) variable in the PEFw equation is now linked to the wind speed variables and will recalculate itself if the wind speed is changed in site-specific mode of the calculator.
  • Corrections were posted to the OSWER Directive (PDF) for child and adult worker surface area available for soil contact. FAQ has been provided. Items 22 and 23 are the source of the documentation.
  • FAQs were added for asbestos and use of the T (total time over which construction occurs, in seconds) variable in the volatilization factor equations.
  • User Guide was updated in section 5.18 regarding the assessment of TCE for less than chronic situations. Additional chemical parameter sources were added to section 2.4.1 and 2.4.2. Section 4.13.4 has new text describing the definition and treatment of volatile compounds.
  • Vapor pressure was added to the Generic Tables in the Chemical Specific Parameters supporting table.

January, 2015

  • Regional Screening Levels Tables were generated to correct the error of omitting the soil ingestion pathway for 17 chemicals. The correction resulted in a lowering of the residential and industrial soil screening levels for these chemicals. Sulfur Trioxide was corrected for an incorrect CAS Number provided by the source and new chemical-specific parameters were added accordingly. Please download this spreadsheet file (or this pdf file) that compares the previous summary table to the current summary table for TR=1E-06 and THQ=1.0. Please download this spreadsheet file (or this pdf file) that compares the previous summary table to the current summary table for TR=1E-06 and THQ=0.1.

    Changes are the following:

    1. Chemicals with new soil ingestion values are:
      Added in November 2014
      • barium chromate,
      • calcium chromate,
      • lead chromate,
      • lead phosphate,
      • nickel acetate,
      • nickel carbonate,
      • nickel hydroxide,
      • nickelocene,
      • perfluorobutane sulfonate,
      • Potassium Perfluorobutane Sulfonate,
      • sodium dichromate,
      • strontium chromate,
      • styrene-acrylonitrile (SAN) trimer and
      • triethylene glycol.
      Added in May 2014
      • aroclor 5460
      Added November 2013
      • Tricresyl Phosphate (TCP) and
      • Thiocyanic Acid.
    2. Sulfur Trioxide CAS number has been corrected.

November, 2014

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.

    Changes are the following:

    1. Chemicals with new toxicity values due to PPRTV updates are:
      • ethyl acrylate,
      • triethylene glycol,
      • isopropanol,
      • styrene-acrylonitrile (SAN) trimer,
      • 1,3-dibromobenzene,
      • perfluorobutane sulfonate and
      • Potassium Perfluorobutane Sulfonate.
    2. Chemicals with new toxicity values due to new Cal EPA updates are:
      • nickelocene,
      • nickel oxide,
      • nickel acetate,
      • lead subacetate,
      • direct black 38,
      • direct blue 6,
      • direct brown 95,
      • nickel carbonate,
      • lead phosphate,
      • sulfur trioxide,
      • lead chromate,
      • strontium chromate,
      • barium chromate,
      • sodium dichromate,
      • nickel hydroxide,
      • nickel carbonyl,
      • calcium chromate and
      • HCDD, 1,2,3,4,6,7,8- (Calculator Only).
    3. naptha, high flash aromatic (HFAN) CAS number has been corrected.
  • Section 5.20 was added to the user guideto explain the RfC source for cyanide.
  • A new FAQ was added to explain the removal of the trans 1,2 dichloroethylene PPRTV.
  • The default intake rate was removed from the fish RSL equations. The fish scenario now requires the Calculator to use Site-Specific mode.
  • The MCL of 15 µg/Lhas been added to the tap water column for lead.
  • Section 5.10 of the user guidewas updated to clarify the use of the arsenic RBA in oral exposure to soil calculations.
  • Additional parameters were added to the Generic Tables in the Chemical Specific Parameters supporting table.
  • FAQ 6 was updated now that the calculator results can be downloaded in a spreadsheet.

May, 2014

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current. There are no files comparing the old and new summary tables because nearly every value has changed due to implementation of Exposure Factor Handbook parameter values.

    Changes are the following:

    1. Chemicals with new toxicity values due to PPRTV updates are:
      • guanidine chloride,
      • guanidine,
      • azodicarbonamide,
      • dicyclopentadiene,
      • 1,2-trans dichloroethylene (See this memo (PDF) for an explanation) and
      • aroclor 5460.
    2. 1,2-dichloroethylene (mixed isomers) was removed from the table and calculator because the RSLs were higher than the individual isomers.
  • An OSWER Directive was released instructing the use of exposure parameters from the Exposure Factors Handbook. All of the RSL equations have been updated accordingly.
  • The cancer toxicity values have been removed for the total petroleum hydrocarbons. See the FAQ page for updates on screening TPHs in risk assessments.
  • The new construction worker landuse equations were modified to more clearly define averaging time and time of exposure for exposures less than one year. For scenarios lasting less than one year, please contact your regional risk assessor for guidance.
  • For the residential landuse, the exposure frequency was moved into the age-adjusted intake portion of the equation. Now each age segment can have a unique exposure frequency.
  • Trichloroethylene SL calculation has changed from a three step process to a seamless calculation. See the TCE FAQ. The User Guide now contains separate equations for TCE similar to those presented for vinyl chloride. User Guide Section 5.18 presents how toxicity adjustment factors were used to combine the cancer and mutagen equations.
  • All Furans were assigned an ABS of 0.03 for this version of the RSLs. RAGS Part E assigned an ABS of 0.03 to all dioxins in exhibit 3-4 but furans were not mentioned. However, the reference provided in RAGS Part E suggests that furans should also be included.
  • A new key column was added to the summary table after the Risk-based SSL column.
  • FAQs were updated or added to explain:
    • how the RSL tables and calculator handle rounding,
    • three and four phase equilibrium modeling,
    • TCE equation changes,
    • TPH screening and
    • use of PPRTV appendix screening levels.

November, 2013

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=1.0. This spreadsheet file (or this pdf file) is a comparison of the previous summary table to the current for TR=1E-06 and THQ=0.1.

    Changes are the following:

    1. Chemicals with new toxicity values due to PPRTV updates are:
      • dinitrotoluene, technical grade,
      • nonane, n-,
      • ethyl acetate,
      • tert-amyl-alcohol,
      • ethoxyethanol, 2-,
      • dimethoxybenzidine, 3,3'-,
      • butylated hydroxytoluene,
      • nitromethane
      • dibenzothiophene
      • dichlorobenzotrifluoride, 3,4- (subchronic only)
      • trinitrophenylmethylnitramine (Tertyl) and
      • endosulfan sulfate (subchronic only).
    2. Chemicals with new toxicity values due to IRIS updates are:
      • Methanol
      • Biphenyl and
      • 1,4-Dioxane.
    3. Chemicals with new toxicity values due to Cal EPA updates are:
      • Butadine, 1,3- and
      • Caprolactam.
  • The calculator page now has an option for the user to enter site concentrations and calculate risk based on the RSL target risk and the RSL concentration. This is a simple calculation where the risk based on the entered media concentration is equal to the RSL target risk multiplied by the user concentration is then divided by the RSL concentration.

    RISK=(RSL_TR x User_C)/RSL_C or
    HQ=(RSL_THQ x User_C)/RSL_C

    The RSL and risk results are presented in the output and available for download. No daily intakes are calculated.

    Whether this calculation will suit the needs of a given project depends upon site-specific decisions, the conceptual site model, the purpose of the risk assessment and the authority under which it is being conducted, etc. Please consult your regional risk assessor for further guidance in site-specific situations.

  • The calculator offers the user to populate the pick list based on CAS number search as well as chemical name.
  • The total petroleum hydrocarbons, previously added to the calculator, have been added to the RSL tables. For the low aliphatic fraction, n-hexane was selected as the representative compound for the toxicity values as well as the chemical-specific parameters. For the medium aliphatic fraction, hydrocarbon streams was selected as the representative compound for the toxicity values and n-nonane was selected to represent the chemical-specific parameters. For the high aliphatic fraction, white mineral oil was selected as the representative compound for the toxicity values as well as the chemical-specific parameters. For the low aromatic fraction, benzene was selected as the representative compound for the toxicity values as well as the chemical-specific parameters. For the medium aromatic fraction, 2-methylnaphthalene was selected as the representative compound for the RfD and naphthalene was selected for the RfC. An average of the chemical-specific parameters for 2-methylnaphthalene and naphthalene was calculated. For the high aromatic fraction, fluoranthene was selected as the representative compound for the toxicity values as well as the chemical-specific parameters.
  • A new construction worker landuse was added to the calculator only. The construction landuse is described in the supplemental soil screening guidance (PDF). This landuse is limited to an exposure duration of 1 year and is thus, subchronic. Other unique aspects of this scenario are that the PEF is based on mechanical disturbance of the soil and a special VF equation is used. In general, the intakes and contact rates are all greater than the outdoor worker. Exhibit 5-1 presents the exposure parameters.
  • For the residential landuse, adult and child noncancer results for soil, tap water and soil to groundwater exposure are now provided in calculator output. This gives the user the ability to calculate RSLs for scenarios where only adults are exposed such as prisons, military bases and retirement communities.
  • The phthalates are now added to their own chemical group and will all appear together in the table like the dioxins and cyanides, etc. do. FAQ 9 is updated accordingly
  • "ethyl chloride" is now listed as "ethyl chloride (chloroethane)".
  • FAQs were added to explain:
    • why IRIS air concentrations and drinking water unit risk values differ from the RSLs,
    • the process of printing the color tables in black and white,
    • how the various EPA regions use the screening tables with different THQs,
    • the Chlordane CAS number selection,
    • how to apply the tap water RSLs to dissolved vs total data and
    • how the TCDD (Dioxin) oral slope factor was chosen.
  • FAQs 9 and 34 were updated.

June, 2013

  • The THQ = 0.1 Tables were corrected for TCE residential land use screening values found in the Summary Table, Soil to Groundwater supporting Table and the Composite Table.
  • If you are unclear about which set of tables (THQ=1.0 or THQ=0.1) to use at your site, contact your EPA regional risk assessment website. The rationale for using THQ of 0.1 for screening is that if 10 chemicals were at a site and all narrowly passed a screening at THQ=1.0, the resulting total HI could actually be 10.

May, 2013

  • Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current.

    All tables are presented with target cancer risk (TR) of 1E-06, however, tables are presented with target hazard quotients (THQ) of 1.0 and 0.1. Use the tables appropriate for your region.

    Changes are the following:

    1. Chemicals with new toxicity values due to PPRTV updates are:
      • Toluene-2,5-diamine,
      • Butylbenzene, tert-,
      • Octyl Phthalate, di-N-,
      • Butylbenzene, sec-,
      • Thiocyanic Acid,
      • Dinitrotoluene, 2,6-,
      • Methyl-1,4-benzenediamine dihydrochloride, 2-,
      • Methylbenzene-1,4-diamine sulfate, 2-,
      • Benzenediamine-2-methyl sulfate, 1,4-,
      • Zirconium and
      • Dinitrotoluene, Technical grade.
    2. Chemicals with new toxicity values due to ATSDR updates are:
      • Uranium (Soluble Salts),
      • 1,4-Dioxane,
      • Tricresyl Phosphate (TCP),
      • Cadmium,
      • Vanadium and Compounds and
      • Tris(1,3-Dichloro-2-propyl) Phosphate.
    3. Chemicals with new toxicity values due to Cal EPA updates are:
      • Nickel Refinery Dust,
      • Nickel Carbonyl,
      • Nickel Oxide and
      • Nickel Subsulfide.
  • Tables are now provided with target hazard quotients (THQ) of 1.0 and 0.1. Use the tables appropriate for your region.
  • The RfDs for the numbered, dioxin-like PCBs are now based on the TCDD (Dioxin) RfD from IRIS and the TEFs presented in User Guide.
  • The high aliphatic and high aromatic TPHs were classified as SVOCs and all the TPHs were given chemical-specific parameters. Chemical-specific parameter assignments were based on the representative compounds identified in the PPRTV paper when available. The medium aliphatic TPH did not have a surrogate listed in the PPRTV paper so n-nonane was assigned. The TPHs are currently available in the calculator only.
  • Glyphosate Koc was updated.
  • Thiocyanic Acid was given the CAS number 463-56-9. This number was previously assigned to Thiocyanate.
  • Vanadium and Compounds was given the CAS number 7440-62-2. Previously it did not have a CAS number. This results in the database matching a RfC from ATSDR.
  • The calculator, if operated in site-specific mode, now gives the option to substitute the Csat for the inhalation route screening level as well as giving the opportunity to substitute the theoretical concentration limit of 1E+05 mg/kg for the total screening level. These two options, combined with the ability change the target risk and the target hazard quotient should provide users with enough flexibility to generate screening levels applicable to many site-specific situations.
  • Arsenic screening levels for ingestion of soil are now calculated with the relative bioavailability factor (RBA) of 0.6. The RBA can be adjusted using the calculator in site-specific/user-provided mode the same way toxicity values can be changed. The RBA for soil ingestion is shown in the calculator output. See Section 5.10 of the User Guide for more information.

January, 2013

In the November 2012 Update, the third to the last bullet that identifies the updates to the recreator landuse scenario, the following additional information may be useful.

The calculator-based recreator landuse scenario shares the following identical default exposure parameters with the residential landuse scenario: body surface area, ingestion rates, body weight and soil adherence factors. Default recreational exposure parameters are not provided for exposure frequency, exposure time and events per day because recreational activities vary greatly and should be derived on a site-specific basis. Please see the User's Guide for the exposure equations and a conceptual model of quantified pathways.
 

November, 2012

  • New Tables were generated that reflect changes in the toxicity and chemical-specific parameters as per the RSL hierarchies. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current. Changes are the following:
    1. The hydrogen cyanide RfC was also assigned to cyanide. Further, the cyanide Kd was also assigned to hydrogen cyanide. This will allow for calculation of a Csat and protection of groundwater SSLs.
    2. Chemicals with new toxicity values due to PPRTV updates are:
      • acetone cyanohydrin,
      • boron trichloride
      • chloroethanol, 2-,
      • cyclohexene,
      • diethanolamine,
      • ethylene cyanohydrin,
      • methacrylonitrile,
      • methyl acrylate,
      • octyl phthalate, di-N-,
      • thallium acetate,
      • thallium carbonate,
      • thallium chloride,
      • thallium (I) nitrate,
      • thallium sulfate,
      • thiocyanate,
      • toluene-2,5-diamine,
      • toluidine, p-,
      • triacetin,
      • tris(1-chloro-2-propyl)phosphate and
      • zirconium.
    3. The RfC for mercuric chloride was replaced with the IRIS RfC for elemental mercury.
  • Changes in chemical-specific parameters were also made. The most significant change was updating the hierarchy of sources for water solubility as it was discovered that some sources were more qualitative than assumed. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous database to the current for parameters not associated with the dermal to tap water route.
  • Thiocyanate was reclassified as an inorganic compound to be equivalent to all the other cyanide compounds.
  • Changes were also made to the parameters involved in dermal exposure to water. Our previous hierarchy used RAGS Part E before using EPI for EPD (effective predictive domain) determination and Kp (dermal permeability) values. Recently released logKows (logp) for some chemicals conflicted with those in RAGS Part E. Specifically for the RSL project, the most recent logKow were used to determine EPD status. To complete the transition the RSLs now also calculate our own FA (fraction absorbed) values. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous database to the current for parameters associated with the dermal to tap water route.
  • To calculate a Csat, the ambient state of the VOC in soil must be known. As indicated in the SSL Guidance, Csat is not calculated for a chemical that is solid at soil temperatures. To make sure this rule was being followed, the melting point database was updated and this rule was established from the SSL guidance: if melting point is less than 20 °C, chemical is a liquid; if melting point is above 20 °C, chemical is solid.
  • The FAQ has been updated in response to user questions.
  • The individual TPHs (total petroleum hydrocarbons) are now available in the RSL calculator.
  • MCLs were added for the following:
    • aldicarb,
    • aldicarb sulfone and
    • aldicarb sulfoxide.
  • The recreator scenario includes additional default exposure parameters that are the same as exposure parameters for the residential scenario.
  • The RSL calculator was updated for the residential scenario site-specific option. The RSL calculator requires separate entries for each age cohort.
  • The RSL calculator output for the "Soil to Groundwater" scenario has been updated to include the SSLs for both cancer and noncancer rather than just the most protective value. The recommended SSL will still be presented. This change is because many chemicals have significant noncancer effects in addition to their cancer risk and should be considered.

May, 2012

  • Tables generated that reflect changes from all the toxicity and chemical-specific parameter sources used in the hierarchies. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current. Changes are:
    1. Uranium (Soluble Salts) lost its ATSDR RfC because it was DRAFT.
    2. Cyanides, Sodium Cyanide, Potassium Cyanide, Potassium Silver Cyanide, Calcium Cyanide have new IRIS RfDs.
    3. Cresol, p-chloro-m- and Cresol, -p now have the ATSDR RfD for Cresols.
    4. Eleven chemicals had their VOC status changed due to updates in Henry's Law constants. Chemicals that were once classified as SVOCS and are now VOCs are: Dihydrosafrole, 2-Chloroacetaldehyde, Propylene, Ethyleneimine, 1,4-Dithiane, Methyl Isocyanate, Mineral Oils and Dimethylvinylchloride. Chemicals that were once VOCs and are now SVOCs are:Isobutyl Alcohol, Cresols and Propylene Glycol Dinitrate.
    5. Tetrahydrofuran (IRIS), Hexamethylphosphoramide (PPRTV) and Sulfalone (PPRTV) are new chemicals.
    6. Tetrachloroethylene, Methylene Chloride and TCDD have new IRIS values.
    7. Methylene Chloride is now classified as a mutagen.
    8. ABS values were assigned for 1 and 2-Methylnaphthalene.
    9. The EPD status for Chlordane was changed.
  • The Recreator landuse was updated to include output for adult as well as child for noncancer. The Equations Page and User's Guide have been updated to reflect this addition.
  • The inputs into the PEF and VF are now included in the calculator output.
  • The NAAQS value for lead was added to Resident Air.
  • The User's Guide has been updated.
  • The FAQ has been updated in response to user questions.

November, 2011

  • Tables generated that reflect changes from all the toxicity sources used in the toxicity hierarchy. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current. Changes are:
    1. Hexachloroethane has a new RFD and SFO from IRIS. IRIS dropped the IUR.
    2. Trichloroacetic Acid is a new chemical with IRIS RfD and SFO.
    3. TCE has new IRIS RfD, RfC, SFO and IUR. TCE is now classified as a mutagen. See the new FAQ.
    4. Chlorpyrifos has the IRIS RfD dropped.
    5. Vanadium Sulfate RfD was dropped from HEAST.
    6. Acrylamide is now treated as a mutagen.
  • TCE has a new IRIS assessment and the RSLs reflect the new toxicity values presented. For land uses that include children's exposure, special calculations are required. Users will be required to run the calculator in site-specific/user-provided mode to generate accurate TCE RSLs. See the new FAQ.
  • This release introduces dermal exposure to tap water equations following RAGS Part E.
  • This release switches from the adult to the child for noncancer tap water RSL equations. Soil and Tap water now follow the same protocol of using the child as the noncancer receptor.
  • Change RSL, PPRTV and HEAST contact information from Dave Crawford/Rich Kapuscinski to Michele Burgess.
  • The User's Guide has been updated.
  • The FAQ has been updated in response to user questions.
  • The Equations Page has been updated to present new tap water equations. Changes include addressing dermal exposures when we have the data from RAGS Part E, and basing the noncancer tap water RSLs upon children's exposures.

June, 2011

  • Tables generated that:
  • Remove the inhalation unit risk value for the analyte "lead and compounds" (which will delete the residential and industrial air SLs that were inadvertently calculated for this analyte).
  • Update soil to groundwater screening levels for the following mutagens: Benzidine, Chromium(VI), Acrylamide, Trichloropropane, 1,2,3-, Nitrosodimethylamine, N-, Methylene-bis(2-chloroaniline), 4,4'-, Nitrosodiethylamine, N-, Benz[a]anthracene, Benzo[a]pyrene, Benzo[b]fluoranthene, Benzo[k]fluoranthene, Chrysene, Dibenz[a,h]anthracene and Indeno[1,2,3-cd]pyrene.
  • Added GIABS and ABS values to newly added analytes.
  • Updated the status of those contaminants determined by EPA to be carcinogenic by a mutagenic mode of action for Acrylamide, Anthraquinone, 9,10-, Benzenediamine-2-methyl sulfate, 1,4-, Methyl-1,4-benzenediamine dihydrochloride, 2-, Methylbenzene,1-4-diamine, monohydrochloride, 2-, Methylbenzene-1,4-diamine sulfate, 2-, Phenothiazine, Trimethylbenzene, 1,2,3-, Dimethylbenz(a)anthracene, 7,12-, Nitroso-N-ethylurea, N-, Methylcholanthrene, 3-, Nitroso-N-methylurea, N-, Safrole and Urethane to reflect the list of contaminants presented in the EPA Office of Solid Waste and Emergency Responses's Handbook for Implementing the Supplemental Cancer Guidance at Waste and Cleanup Sites described in Section 5.15 of the RSLs' User's Guide.\

May, 2011

  • Tables generated that reflect changes from all the toxicity sources used in the toxicity hierarchy. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current.
  • Subchronic toxicity values are now available for assessment of less than chronic scenarios. This option is only available in the calculator. None of the RSLs in the download tables are calculated with subchronic toxicity values because all of those scenarios are assumed to be chronic for screening purposes. Scenarios less than seven years exposure duration may or may not be judged as chronic in the risk assessment. Consult your regional risk assessor for further guidance on this matter.
  • A recreational scenario is now available in the RSL calculator. Surface water and sediment/soil can be evaluated. The EPA provides very few default exposure parameters so users are encouraged to have a strong understanding of their receptor prior to use and are required to use the "site-specific" option. The landuse equations are presented in the User Guide and the Equations page. The recreational scenario assess dermal exposure to water following RAGS Part E guidance. This feature required many new supporting equations to be developed.
  • The User's Guide has been updated.
  • FAQs 9, 16, 18, 33, 36 and 38 have been updated in response to user questions.
  • All the perchlorates are grouped together in the tables.
  • All the phosphates are grouped together in the tables.
  • The database of the RSL sources for chemical-specific parameters was updated. EPI, CRC, Perry's, Lange's and Yaw's were updated.

February, 2011

  • The restriction on acess to the PPRTV website has been lifted. PPRTVs can be accessed from links in section 2.3 of the user guide and FAQ#27.

November 11, 2010

  • Tables generated that reflect changes from all the toxicity sources used in the toxicity hierarchy. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current.
  • The User's Guide has been updated.
  • The FAQ has been updated in response to user questions. The FAQ has also been reorganized into 5 topics to facilitate searching.
  • TEFs have been applied to noncarcinogenic toxicity values for the dioxin like PCBs.
  • "Mercuric Sulfide" and "Mercury, Inorganic Salts" were removed from the table and "Mercuric Chloride" was renamed "Mercuric Chloride (and other Mercury salts)".
  • "Manganese water" was renamed "Manganese non-diet".

May 17, 2010

  • Tables generated that reflect changes from all the toxicity sources used in the toxicity hierarchy. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current.
  • The User's Guide has been updated.
  • The FAQ has been updated in response to user questions.
  • The contaminant names and CAS numbers have been moved to the center of the tables. This change was implemented so that the contaminant name would nearly always be visible on your screen.

December 7, 2009

  • Tables generated that reflect changes from all the toxicity sources used in the toxicity hierarchy. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current.
  • The User's Guide has been updated.
    • A new source of toxicity values used was added: screening toxicity values in an appendix to certain PPRTV assessments. While we have less confidence in a screening toxicity value than in a PPRTV, we put these ahead of HEAST toxicity values because these appendix screening toxicity values are more recent and use current EPA methodologies in the derivation, and because the PPRTV appendix screening toxicity values also receive external peer review.
  • The FAQ has been updated in response to user questions.
  • The database of chemical-specific parameters was updated. In particular, EPI had significant improvements to its Koc program. Changes in Koc effect calculations of the Volatilization Factor, Soil Screening Levels and Soil Saturation Concentrations.

April 15, 2009

  • Tables generated that reflect changes from all the toxicity sources used in the toxicity hierarchy. This spreadsheet file (or this pdf file (PDF)) is a comparison of the previous toxicity database to the current.
  • The User's Guide has been updated.
    • The generic tables no longer provide individual SLs for dioxin-like congeners. The User's Guide provides instructions on how to apply the TEFs.
    • RAGS Part F guidance has been incorporated into the FAQ and User's Guide.
    • The OSWER Cancer Handbook guidelines have been incorporated into a new section in the user guide addressing mutagens (Section 5.14).
    • A detailed discussion of the sources of Kd values has been added to Section 4.9 of the User's Guide.
    • Section 5.12 was added to the User's Guide to address potential methods of screening sites with multiple contaminants.
  • The FAQ has been updated in response to user questions.

October 16, 2008: Summary of Changes Posted

  • Spreadsheet of changes (XLS)
  • Notes about the Spreedsheet of changes 
    1) purple row = chemical no longer in table due to no values 
    2) green row = chemical added 
    3) yellow boxes = differences
  • For the yellow differences, prior (June) value is on top and current (September) value is below. Letter differences are due to change in tox source and possible tox value. Note the "C" iur values which were in wrong units from Cal EPA but are correct now.
  • Most metals differ in soil to groundwater calculations. All PCBs/Dioxins that have "W" have been modified with newer TEF."

September 12, 2008

  • New Tables generated that reflect the addition of several PPRTVs. Beta designation is removed.

July 7, 2008

  • New Tables generated that reflect the addition of the Cal EPA IUR for Naphthalene.

July 3, 2008

  • New Tables generated that reflect the correction of the IUR for Ethylene oxide.

July 2, 2008

  • New Tables generated that reflect the removal of the Cal EPA RfC for Trichloroethylene (TCE). After careful consideration, it was determined that the resulting noncancer screening level may not be protective of non-carcinogenic effects.

June 20, 2008

  • New Tables generated that corrected the usage of the "nc" and "ca**" designation in the Summary Table for Tap Water.

June 17, 2008

  • New Tables generated that corrected the usage of the "ca**" designation in the Summary Table.

June 13, 2008

  • Some duplicate rows were removed from the residential tap water supporting table.

May 2008

  • Website open as a Beta release.
  • The lead action level presented in the Generic Tables was changed from 0.015 to 15 ug/L.
  • The copper action level presented in the Generic Tables was changed from 1.3 to 1300 ug/L.
  • The labels for adult and child body weight in the Calculator output were corrected.
  • The target risk labels in the Resident Air Supporting Table were corrected.
  • The Inhalation Unit Risk for TCDD was changed to 38 and the Generic Tables were updated.

For assistance/questions please use the Regional Screening Levels (RSLs) contact us page. For general risk assessment questions, separate from the RSLs, please use the link below.

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Last updated on November 13, 2024