Perchlorate is considered an ongoing emerging contaminant because toxicity information is being updated and re-evaluated; more information has been developed on sources and pathways of human exposure, and the U.S. Environmental Protection Agency (EPA) is working to set standards for perchlorate in drinking water under the Safe Drinking Water Act.

In 2007, Massachusetts was the first state in the country to set drinking water and hazardous waste site cleanup standards for perchlorate. Perchlorate is used in rocket fuel, munitions, fireworks, flares, some blasting agents and can be a contaminant in certain drinking water disinfection products. It is an endocrine disrupter and affects thyroid hormone levels responsible for normal growth and development. In 2011, EPA announced plans for setting an Maximum Contaminant Level (MCL) for perchlorate, reversing a 2009 decision not to regulate perchlorate in drinking water. Since MassDEP set its standards, new information has emerged on perchlorate’s toxicity, sources of exposure and body burdens in the U.S. population. EPA has also developed updated methodologies for assessing the toxicity of chemicals and for deriving toxicity values used to set health protection standards.

MassDEP Workplan:

It is important for MassDEP to review and evaluate EPA’s work, and to comment on proposed federal rulemaking. Specifically, the agency will:

  • Review and comment on EPA’s proposed Maximum Contaminant Level Goal (MCLG, a health-based level) when it is published in the Federal Register.
  • Also review and comment on EPA’s proposed MCL (a level that considers health risk, cost and feasibility).
  • Consider adopting EPA’s MCL for Massachusetts or maintaining its current state MCL, which is allowed if it is more protective than the EPA standard. Any modifications to the existing Massachusetts perchlorate toxicity value and standards will require consultation with the MassDEP Bureau of Waste Site Cleanup.

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