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Risk Assessment

Regional Screening Levels (RSLs) - What's New

 

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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 19, 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.
  • 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 generic dioxin 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 tapwater.
  • The FAQs 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 FAQ 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

  • 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 (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 CalEPA. 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 Propanediol, 1,2-
    • 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 FQ 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 Tapwater and Soil to Groundwater Tables were generated that reflect a correction in the tapwater 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 (PDF) 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. A FAQ (PDF) 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

  • New 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

  • 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. 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 guide to 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 tapwater column for lead.
  • Section 5.10 of the user guide was 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

  • 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. 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

  • 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. 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, tapwater 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 tapwater 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

  • 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.

    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.
  • New 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 tapwater 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 tapwater 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

  • New 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

  • New 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 tapwater equations following RAGS Part E.
  • This release switches from the adult to the child for noncancer tapwater RSL equations. Soil and Tapwater 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 tapwater equations. Changes include addressing dermal exposures when we have the data from RAGS Part E, and basing the noncancer tapwater RSLs upon children's exposures.

June, 2011

  • New 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

  • New 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

  • New 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

  • New 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

  • New 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

  • New 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 CALEPA 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 CalEPA 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 Tapwater.

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 tapwater 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.