Perchlorate in California Drinking Water

THE MESS

Perchlorate (ammonium perchlorate), is used as an oxidant (energetics booster) in solid propellant for rockets, missiles and fireworks. Perchlorate can be found in matches, flares, pyrotechnics, and explosives.

Perchlorate has been known to be a widespread inorganic contaminant found in California drinking water since 1985, however perchlorate contamination of water sources nationwide was not recognized until 1997. The U.S. Environmental Protection Agency (EPA) estimated that approximately 11 million people nationwide are exposed to perchlorate in their public drinking water supplies. This estimate was based on a data sampling collected as of May 2004, showing the Minimum Reporting Level for that date of collection at four parts per billion (ppb).

Unfortunately there is not a drinking water standard for perchlorate, known as a maximum contaminant level (MCL). The California Department of Health Services has proposed that an MCL be established for perchlorate by the end of this year.

The National Academy of Sciences' report, "Health Implications of Perchlorate Ingestion", which was released January 2005, includes a review of the U.S. Environmental Protection Agency's assessment, originally released in 2002. The EPA's report will be used in developing the federal MCL. In the meantime, the California Department of Health Services will notify statewide water systems of any perchlorate findings in the water above six parts per billion.

The EPA's 2002 findings show birth defects in children and tumors in adults as possible affects of inhibition of thyroid iodide uptake. The committee reviewing the findings can only conclude that humans exposed to perchlorate have suffered an inhibition of thyroid iodide.