Perchlorate is a naturally occurring and manufactured chemical anion that consists of one chlorine atom bonded to four oxygen atoms (ClO4-). Perchlorate is commonly used as an oxidizer in rocket propellants, munitions, fireworks, airbag initiators for vehicles, matches and signal flares. It is naturally occuring in some fertilizers.
On February 11, 2011, EPA determined that perchlorate meets the Safe Drinking Water Act criteria for regulation as a contaminant. The Agency found that perchlorate may have an adverse effect on the health of persons and is known to occur in public drinking water systems with a frequency and at levels that present a public health concern. Since that time, EPA has been reviewing the best available scientific data on a range of issues related to perchlorate in drinking water including its occurrence, treatment technologies, analytical methods and the costs and benefits of potential standards.
EPA has collaborated with Food and Drug Administration scientists to implement the 2013 Science Advisory Board (SAB) recommendations to develop a Physiologically Based Pharmacokinetic (PBPK) or Biologically Based Dose Response model that will integrate available health related information in a robust and transparent analysis of the effects of perchlorate on thyroid hormone production.
Technical Fact Sheet
A technical fact sheet has been developed for perchlorate that includes: physical and chemical properties; environmental health impacts; existing federal and state guidelines; and detection and treatment methods.
Perchlorate Reference Dose
EPA has established a reference dose (RfD) for perchlorate, which is consistent with the reference dose recommended by the National Research Council’s 2005 report.
Interim Health Advisory
In January 2009, EPA issued an Interim Health Advisory for perchlorate to assist state and local officials in addressing local contamination of perchlorate in drinking water while the Agency conducted its evaluation of the opportunity to reduce risks through a national primary drinking water regulation.
Federal Register Notices
Public Meeting Notices
Final Regulatory Determination Notice for Perchlorate
EPA decided to regulate perchlorate under the Safe Drinking Water Act (SDWA). The science that lead to this decision has been peer reviewed by independent scientists and public health experts including the National Academy of Sciences.
Supplemental Request for Comments on Preliminary Regulatory Determination
On August 19, 2009, EPA published the Perchlorate Supplemental Request for Comments requesting comment on additional approaches to analyzing data related to EPA’s perchlorate preliminary regulatory determination.
Preliminary Regulatory Determination Notice for Perchlorate
On October 10, 2008, EPA published a preliminary regulatory determination for perchlorate. This notice requested public comment on its determination that perchlorate did not occur with a frequency and at levels of public health concern and that development of a regulation did not present a meaningful opportunity for health risk reduction for persons served by public water systems.
Additional information including support documents for the regulatory determination may be found in:
Regulatory Determination Fact Sheets
Read about perchlorate's regulatory stage in EPA's Regulatory Development and Retrospective Review Tracker