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 level
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 Contamination. 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/L 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 Advisory 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 Perchlorate, 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. 
EPA'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. National 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. Revised Assessment Guidance for Perchlorate. 2 pp.
EPA, 2008a. Drinking Water: Preliminary Regulatory Determination on Perchlorate.
EPA, 2008b. Interim Drinking Water Health Advisory For Perchlorate. EPA 822-R-08-025, 49 pp.
EPA, 2006. Assessment Guidance for Perchlorate. 3 pp.
EPA, 2005. Perchlorate (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)
Reductions of Perchlorate in Drinking Water
EPA Office of Ground Water and Drinking Water, EPA-815-F-20-002, 13 pp, 2020
Steps 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
Perchlorate 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
Assessment Guidance for Perchlorate
EPA Office of Solid Waste and Emergency Response. 3 pp, 2006
Policy on DoD Required Actions Related to Perchlorate
Office of the Under Secretary of Defense 3 pp, 2006
State Resources
Perchlorate 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
Alabama Risk-Based Corrective Action Guidance Manual
Alaska 18 AAC 75 Oil and Other Hazardous Substances Pollution Control
Arkansas Water Quality Standards
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
Connecticut Department of Public Health Fact Sheet Perchlorate
Delaware Department of Natural Resources HSCA Screening Level Table
Florida Table 1 – Groundwater and Surface Water Cleanup Target Levels
Illinois Environmental Protection Agency – Non-Taco Class I and Class II Groundwater Objectives
Indiana Department of Environmental Management 2022 Screening Level Table (A-6)
Risk-Based Standards for Kansas RSK Manual – 6th Version
Maine Remedial Action Guidelines for Sites Contaminated with Hazardous Substances
Nevada Drinking Water Standard for Perchlorate
Maryland Department of the Environment Cleanup Standards for Soil and Groundwater
Michigan Department of Environmental Quality Cleanup Criteria Requirements for Response Activity
New Jersey Department of Environmental Protection Ground Water Quality Standards
North Carolina Groundwater Interim Maximum Allowable Concentrations
Perchlorate Answers to Frequently Asked Health Questions
Ohio Department of Health, 3 pp, 2016
Groundwater Quality Protection In Oregon
Technical Bulletin Health Effects Information: Perchlorates
Oregon Department of Human Services
2018 Texas Surface Water Quality Standards
Texas Commission on Environmental Quality
Washington Department of Ecology Water Quality
West Virginia Appendix H.3-Action Levels-De Minimis Table 2017
Wisconsin Department of Natural Resources Regional Screening Levels
Helpful Information
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. ↩
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. ↩
A reference dose (RfD) is a scientific estimate of a daily exposure level that is not expected to cause adverse health effects in humans. ↩
A reference dose (RfD) is a scientific estimate of a daily exposure level that is not expected to cause adverse health effects in humans. ↩
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. ↩
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. ↩
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). ↩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). ↩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. ↩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. ↩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). ↩
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). ↩
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. ↩
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. ↩
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. ↩
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. ↩
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). ↩
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). ↩