Regulatory actions related to perchlorate have been under review and consideration in the United States since the mid-1990’s.
The subject was controversial enough that a review by National Research Council was commissioned, which resulted in setting of an oral reference dose (Rfd) that translates into a "drinking water equivalent level" of 24.5 micrograms/L.
In February 2011, the US Environmental Protection Agency reversed the 2009 preliminary regulatory determination that perchlorate did not present a meaningful opportunity to protect public health, which is a regulatory criterion of the Safe Drinking Water Act. The agency based its decision on a new analysis of the potential health impacts to newborns and infants with a lower body weight and higher water consumption.
EPA's determination to regulate perchlorate is the first under the Contaminant Candidate List rulemaking process. Prior to the positive perchlorate decision, EPA had made 20 negative determinations off the first two CCLs.
To support its decision-making process, the agency formed a panel of the Science Advisory Board to review the scientific and technical bases for the approaches being considered for deriving a Maximum Contaminant Level Goal for perchlorate.
The development of a perchlorate MCLG involves several complex and unresolved scientific questions, including use of a “life-stages” analysis and shifting the mode of action to a non-adverse effect. The last two issues could be precedent-setting for future regulations based on the increased amount of water consumed per body weight for infants and toddlers as compared to adults, and the use of “health effects” that are not adverse.
On June 3, 2016, EPA published a Request for Nominations for Peer Reviewers for EPA's Draft Biologically Based Dose-Response (BBDR) Model for Perchlorate, Draft Model Support Document and Draft Approach for Deriving a Maximum Contaminant Level Goal (MCLG) for Perchlorate in Drinking Water
California: Perchlorate is a regulated drinking water contaminant in California, with a maximum contaminant level of 6 micrograms/L. The regulation became effective October 2007.
Massachusetts: A perchlorate standard of 2 micrograms/L became effective in 2006 in Massachusetts.
In October 2013, AWWA published a report that updates estimated costs of an anticipated perchlorate standard being developed by EPA.
The new cost-impact assessment updates a 2009 review by including additional treatment strategies and accounting for regulatory limits already in place in California and Massachusetts.
In addition to ion exchange, this assessment considers also costs associated with blending, source abandonment and development of new sources. In all, the estimated national compliance costs for a perchlorate maximum contaminant level ranging from 2 to 24 ppb is smaller than estimated compliance costs for other drinking water regulations.
AWWA has offered the following comments to EPA:
In addition, as the regulatory review of perchlorate evolved AWWA has conducted several analyses to inform our comment development and in anticipation of potential utility needs.