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What's New

Table of Contents

For assistance/questions please use the rsl table 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.

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 in 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) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf file) 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:
      • 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) 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 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:

    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) is a comparison of the previous toxicity database to the current. This spreadsheet file (or this pdf file) 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. 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:
  • FAQs 9 and 34 were updated.

    June, 2013

    May, 2013

    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

    May, 2012

    November, 2011

    June, 2011

    May, 2011

    February, 2011

    November 11, 2010

    May 17, 2010

    December 7, 2009

    April 15, 2009

    October 16, 2008: Summary of Changes Posted

    September 12, 2008

    July 7, 2008

    July 3, 2008

    July 2, 2008

    June 20, 2008

    June 17, 2008

    June 13, 2008

    May 2008

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    For assistance/questions please use the rsl table contact us page

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