Perchlorate in Drinking Water
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.
As part of EPA’s commitment to ensuring the safety of America’s drinking water, the Agency conducted two independent, expert peer reviews to determine the appropriate scientific approach for understanding the adverse health impacts of perchlorate in drinking water.
EPA collaborated with Food and Drug Administration scientists to implement the 2013 Science Advisory Board (SAB) recommendations to develop a Physiologically Based Pharmacokinetic/Pharmacodynamic (PBPK/PD) or Biologically Based Dose Response (BBDR) model that integrated available health related information in a robust and transparent analysis of the effects of perchlorate on thyroid hormone production. A peer review was conducted on the draft model and model report in January 2017. After considering the findings of this review, EPA revised the Perchlorate BBDR Model to focus on increasing the scientific rigor of the model and modeling results. In addition, EPA developed a two-stage approach linking the revised BBDR model results with quantitative information on neurodevelopmental outcomes from epidemiological studies. EPA also developed an alternative population-based approach that uses the revised Perchlorate BBDR Model to evaluate a shift in the population of pregnant women who could be hypothyroxinemic.
The final reports for both peer reviews are available through Docket ID No. EPA-HQ-OW-2016-0439.
Technical Fact Sheet
Perchlorate Reference Dose
Interim Health Advisory
Interim Drinking Water Health Advisory for Perchlorate, EPA 822-R-08-25, December 2008
Federal Register Notices
Public Meeting Notices
- Notice of a Public Meeting: Stakeholder Meeting Concerning EPA's Intent To Regulate Perchlorate Levels in Drinking Water - September 20, 2012
- Notification of a Public Meeting and Public Teleconference of the Science Advisory Board: Perchlorate Advisory Panel - July 18-19, 2012 and September 25, 2012
- Notice of a Public Meeting: Environmental Justice Considerations for Drinking Water Regulatory Efforts - March 3, 2011