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Perchlorate

Policy and Guidance

Under CERCLA, Preliminary Remediation Goals (PRGs)1 are the starting points in the development of site-specific cleanup levels. At all sites addressed under the National Contingency Plan (NCP), PRGs may be modified, depending on the physical characteristics of a site, state laws and guidance, and other site-specific factors.

EPA's Office of Land and Emergency Management recommends 15 µg/L (or 15 parts per billion) as the PRG for perchlorate at Superfund sites where there is an actual or potential drinking water exposure pathway and no applicable or relevant and appropriate (ARAR) requirements exist under federal or state laws (EPA, 2009). EPA also has established soil screening levels (SSLs) for perchlorate and perchlorate salts (ammonium, potassium, and sodium) at Superfund sites: 55 mg/kg for residential areas at Superfund sites and 820 mg/kg for industrial areas (EPA, 2022).

EPA's 14 µg/L tapwater screening levelAdobe PDF Logo for perchlorate applies to current and potential drinking water sources. This value is based on EPA's reference dose (RfD)2 and use of standard Regional Screening Level (RSL)3 equations, the most recent science, and CERCLA assumptions. Since RfDs may change over time as new information becomes available, the most recent RSL calculator and associated guidance should be reviewed to ensure that the risk assessment is based on the most recent and defensible science in accordance with CERCLA.

The following is an overview of the policy history of perchlorate leading up to EPA's March 31, 2022, plan to protect the public from perchlorate in drinking water and EPA's July 21, 2020, Final Action on Perchlorate in Drinking Water.

  • On March 31, 2022, EPA announced its plan4 to pursue multiple integrated actions to address perchlorate in drinking water and the environment and published a Fact Sheet: EPA's Plan to Address Perchlorate ContaminationAdobe PDF Logo. On July 21, 2020, EPA published a Drinking Water: Final Action on Perchlorate, in the Federal Register, which withdrew its 2011 determination to regulate perchlorate as a drinking water contaminant under the SDWA. EPA based its 2020 final action on proactive steps5 that EPA, states, and public water systems have taken to reduce perchlorate levels and on its new health impact analysis, which showed that concentrations at which perchlorate may present a public health concern are higher than the concentrations considered in 2011 (see below).
  • In 2019, EPA released its proposed national primary drinking water regulation for public comment on alternative actions to regulate perchlorate (EPA, 2019).
  • In 2017, EPA calculated a tap water RSL of 14 µg/L for perchlorate and perchlorate salts based on EPA's RfD and using standard RSL equations (EPA, 2017).
  • In 2011, EPA published a determination to regulate perchlorate in drinking water and initiated the process of proposing a national primary drinking water regulation (EPA, 2011).
  • In 2009, EPA's Office of Solid Waste and Emergency Response recommended a PRG of 15 µg/LAdobe PDF Logo for perchlorate at Superfund sites where there is a potential or actual drinking water exposure pathway and no applicable or relevant and appropriate requirements exist under federal or state laws (EPA, 2009).
  • In 2008, EPA established an Interim Drinking Water Health AdvisoryAdobe PDF Logo of 15 µg/L for perchlorate (EPA 2008b) based on analysis performed by the Office of Water.
  • In 2008, EPA published a preliminary regulatory determination that regulating perchlorate in drinking water would not present a "meaningful opportunity for health risk reduction" and requested public comment (73 FR 60262; EPA 2008a).
  • In 2006, Massachusetts became the first state in the nation to promulgate a drinking water standard, or maximum contaminant level, for perchlorate, at 2 µg/L. California followed in 2007, setting its standard at 6 µg/L.
  • In 2006, EPA's Office of Solid Waste and Emergency Response (OSWER) issued the memorandum, Assessment Guidance for PerchlorateAdobe PDF Logo, applying the 0.0007 mg/kg/day RfD to the CERCLA program. The guidance replaced previous OSWER guidance on perchlorate that endorsed a provisional RfD range of 0.0001 to 0.005 mg/kg/day.
  • In 2005, EPA adopted an oral RfD of 0.0007 milligrams of perchlorate per kilogram of body weight per day (mg/kg/day). This level is consistent with the recommended RfD contained in the National Research Council of National Academies' report, Health Implications of Perchlorate Ingestion (National Research Council, 2005). The RfD translates to a Drinking Water Equivalent Level6 (DWEL) of 24.5 µg/L, a non-regulatory value (EPA, 2005).
  • EPA placed perchlorate on the first, second, and third7 Contaminant Candidate Lists (CCL)8 (published in 1998, 2005, and 2009) for possible regulation. Drinking water systems were monitored for perchlorate under the first Unregulated Contaminant Monitoring Rule (UCMR)9 in 1999.

References:

EPA, 2022. Adobe PDF LogoEPA's Plan to Address Perchlorate Contamination. March 2022.

EPA, 2022. Regional Screening Levels (RSLs) — Generic Tables. Website consulted May 2022.

EPA, 2020. Drinking Water: Final Action on Perchlorate. Federal Register 85(140): 43990-44002

EPA, 2019. Adobe PDF LogoNational Primary Drinking Water Regulation for Perchlorate: Proposed Rule. 23 slides

EPA, 2017. Regional Screening Levels (RSLs) — User's Guide. Section 5.26

EPA, 2011. Drinking Water: Regulatory Determination on Perchlorate. Federal Register 76(2): 7762-7767

EPA, 2009. Adobe PDF LogoRevised Assessment Guidance for Perchlorate. 2 pp.

EPA, 2008a. Drinking Water: Preliminary Regulatory Determination on Perchlorate.

EPA, 2008b. Adobe PDF LogoInterim Drinking Water Health Advisory For Perchlorate. EPA 822-R-08-025, 49 pp.

EPA, 2006. Adobe PDF LogoAssessment Guidance for Perchlorate. 3 pp.

EPA, 2005. Adobe PDF LogoPerchlorate (ClO4-) and Perchlorate Salts Integrated Risk Information System (IRIS) Chemical Assessment Summary, 22 pp.

Interstate Technology Regulatory Council (ITRC), 2005. Perchlorate: Overview of Issues, Status, and Remedial Options. PERC-1, 152 pp.

National Research Council. 2005. Health Implications of Perchlorate Ingestion. Washington, DC: The National Academies Press.


Federal Resources

Drinking Water: Final Action on Perchlorate
EPA, Federal Register 85 FR 43990, 85(140):43990-44002(2020)

Adobe PDF LogoReductions of Perchlorate in Drinking Water
EPA Office of Ground Water and Drinking Water, EPA-815-F-20-002, 13 pp, 2020

Adobe PDF LogoSteps Water Systems Can Take to Address Perchlorate in Drinking Water
EPA Office of Ground Water and Drinking Water, EPA 815-F-20-001, 4 pp, 2020

Adobe PDF LogoPerchlorate Occurrence Is Widespread At Varying Levels; Federal Agencies Have Taken Some Actions to Respond to and Lessen Releases Assessment Guidance for Perchlorate
Government Accountability Office, GAO-10-769, 63 pp, 2010

Adobe PDF LogoAssessment Guidance for Perchlorate
EPA Office of Solid Waste and Emergency Response. 3 pp, 2006

Adobe PDF LogoPolicy on DoD Required Actions Related to Perchlorate
Office of the Under Secretary of Defense 3 pp, 2006

State Resources

Adobe PDF LogoPerchlorate Policy Update
ASTSWMO Federal Facilities Research Center, Emerging Issues Focus Group, 16 pp, 2011

Perchlorate: Overview of Issues, Status, and Remedial Options
Interstate Technology & Regulatory Council (ITRC) Perchlorate Team, PERC-1, 152 pp, 2005

Adobe PDF LogoAlabama Risk-Based Corrective Action Guidance Manual

Adobe PDF LogoAlaska 18 AAC 75 Oil and Other Hazardous Substances Pollution Control

Arkansas Water Quality Standards

Adobe PDF LogoArizona Notice of Final Rulemaking Title 18. Environmental Quality Chapter 7. Department of Environmental Quality Remedial Action

California: Perchlorate in Drinking Water

Final Technical Support Document on the Public Health Goal for Perchlorate in Drinking Water

California DTSC Perchlorate & Best Management Practices Fact Sheet

Three Scientific Peer Reviews of the Office of Environmental Health Hazard Assessment's December 2002 Draft Public Health Goal (PHG) Document on Perchlorate in California Drinking Water

Adobe PDF LogoConnecticut Department of Public Health Fact Sheet Perchlorate

Colorado Department of Public Health and Environment, Regulation No. 41 – The Basic Standards for Groundwater

Adobe PDF LogoDelaware Department of Natural Resources HSCA Screening Level Table

Florida Table 1 – Groundwater and Surface Water Cleanup Target Levels

Adobe PDF LogoHawaii Department of Health Environmental Management Division Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater Volume 1: User's Guide

Illinois Environmental Protection Agency – Non-Taco Class I and Class II Groundwater Objectives

Indiana Department of Environmental Management 2022 Screening Level Table (A-6)

Adobe PDF LogoRisk-Based Standards for Kansas RSK Manual – 6th Version

Adobe PDF LogoMaine Remedial Action Guidelines for Sites Contaminated with Hazardous Substances

Nevada Drinking Water Standard for Perchlorate

Adobe PDF LogoMaryland Department of the Environment Cleanup Standards for Soil and Groundwater

Massachusetts Department of Environmental Protection Perchlorate Background Information and Standards

Michigan Department of Environmental Quality Cleanup Criteria Requirements for Response Activity

Adobe PDF LogoNew Jersey Department of Environmental Protection Ground Water Quality Standards

North Carolina Groundwater Interim Maximum Allowable Concentrations

2022 New Mexico Environment Department Risk Assessment Guidance for Site Investigations and Remediation

Adobe PDF LogoPerchlorate Answers to Frequently Asked Health Questions
Ohio Department of Health, 3 pp, 2016

Adobe PDF LogoGroundwater Quality Protection In Oregon

Adobe PDF LogoTechnical Bulletin Health Effects Information: Perchlorates
Oregon Department of Human Services

Pennsylvania Department of Environmental Protection Statewide Health Standards, Revised MCLs, and HALs

2018 Texas Surface Water Quality Standards
Texas Commission on Environmental Quality

Adobe PDF LogoVermont Department of Environmental Conservation, Environmental Protection Rules Chapter 35: Investigation and Remediation of Contaminated Properties Rule: State of Vermont

Washington Department of Ecology Water Quality

West Virginia Appendix H.3-Action Levels-De Minimis Table 2017

Adobe PDF LogoWisconsin Department of Natural Resources Regional Screening Levels


Helpful Information

  1. Preliminary Remediation Goal (PRG) is the average concentration of a chemical in an exposure area that will yield the specified target risk in an individual who is exposed at random within the exposure area.  ↩

  2. Preliminary Remediation Goal (PRG) is the average concentration of a chemical in an exposure area that will yield the specified target risk in an individual who is exposed at random within the exposure area.  ↩

  3. A reference dose (RfD) is a scientific estimate of a daily exposure level that is not expected to cause adverse health effects in humans.  ↩

  4. A reference dose (RfD) is a scientific estimate of a daily exposure level that is not expected to cause adverse health effects in humans.  ↩

  5. Screening levels (SLs) are risk-based concentrations derived from standardized equations that combine exposure information assumptions with EPA toxicity data. SLs are used to help identify areas, contaminants, and conditions that may require further evaluation of the potential risks by contaminants at a site. ↩

  6. Screening levels (SLs) are risk-based concentrations derived from standardized equations that combine exposure information assumptions with EPA toxicity data. SLs are used to help identify areas, contaminants, and conditions that may require further evaluation of the potential risks by contaminants at a site.  ↩

  7. EPA plans to include:
    Continue ongoing cleanup activities at perchlorate-contaminated sites.

    Propose revisions to the RCRA standards for the open burning and open detonation of waste explosives and bulk propellants to reduce impacts of perchlorate to human health and the environment.

    Strengthen labeling requirements for hypochlorite solutions that include storage and handling information to minimize perchlorate formation.

    Provide resources and recommendations for water systems to address perchlorate contamination. (EPA, 2022). ↩

  8. EPA plans to include:
    Continue ongoing cleanup activities at perchlorate-contaminated sites.

    Propose revisions to the RCRA standards for the open burning and open detonation of waste explosives and bulk propellants to reduce impacts of perchlorate to human health and the environment.

    Strengthen labeling requirements for hypochlorite solutions that include storage and handling information to minimize perchlorate formation.

    Provide resources and recommendations for water systems to address perchlorate contamination. (EPA, 2022). ↩

  9. Proactive steps include:
    Drinking water regulations for perchlorate in Massachusetts and California.

    Federal and state remediation activities to clean up perchlorate contamination, particularly in the State of Nevada.

    Improved storage and handling procedures of hypochlorite solutions used to disinfect drinking water. ↩

  10. Proactive steps include:
    Drinking water regulations for perchlorate in Massachusetts and California.

    Federal and state remediation activities to clean up perchlorate contamination, particularly in the State of Nevada.

    Improved storage and handling procedures of hypochlorite solutions used to disinfect drinking water. ↩

  11. A Drinking Water Equivalent Level (DWEL) is a drinking water lifetime exposure level, assuming all exposure to a contaminant comes from drinking water, at which adverse health effects would not be expected to occur. (EPA, 2018). ↩

  12. A Drinking Water Equivalent Level (DWEL) is a drinking water lifetime exposure level, assuming all exposure to a contaminant comes from drinking water, at which adverse health effects would not be expected to occur. (EPA, 2018). ↩

  13. While waiting for the UCMR sampling results, EPA rolled perchlorate into the second CCL and subsequently the third CCL since a regulatory determination had not been made. ↩

  14. While waiting for the UCMR sampling results, EPA rolled perchlorate into the second CCL and subsequently the third CCL since a regulatory determination had not been made. ↩

  15. EPA's Contaminant Candidate List is a list of drinking water contaminants that are known or anticipated to occur in public water systems and are not currently subject to any proposed or promulgated national primary drinking water regulations (NPDWR). An NPDWR sets a Maximum Contaminant Level or specifies a certain treatment technique for public water systems for a contaminant. ↩

  16. EPA's Contaminant Candidate List is a list of drinking water contaminants that are known or anticipated to occur in public water systems and are not currently subject to any proposed or promulgated national primary drinking water regulations (NPDWR). An NPDWR sets a Maximum Contaminant Level or specifies a certain treatment technique for public water systems for a contaminant. ↩

  17. EPA uses the Unregulated Contaminant Monitoring Rule to collect data for contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act (SWDA). ↩

  18. EPA uses the Unregulated Contaminant Monitoring Rule to collect data for contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act (SWDA). ↩