New Information on Perchlorate Contamination

Perchlorate contamination has become an issue of great concern across the nation due to the chemical’s potential to adversely affect thyroid gland function at very low concentrations. Perchlorate is a primary component of solid rocket fuels and is used in the manufacture of ordnance, explosives, fireworks, matches, and flares. Recently it has been found in drinking water supplies and foods across the U.S. TOSC staff recently attended two conferences on perchlorate to learn more about its occurrence, toxicity, and cleanup.

The first conference, Perchlorate in Groundwater: Occurrence, Analysis, and Treatment, took place on July 31, 2003 in Sacramento, California. TOSC staff also attended a conference on tribal concerns related to perchlorate contamination. This conference took place in Parker, Arizona on September 9 and 10, 2003. Topics discussed at these conferences included sources, geochemistry, fate and transport, analysis, remediation and toxicity of perchlorate. The conferences also included case study presentations on perchlorate contamination of drinking water supplies.

Groundwater Resources Association of California organized and hosted the first conference. The presentations on toxicity and analysis of perchlorate were particularly interesting. The California EPA Office of Environmental Health Hazard Assessment spoke about the status of the public health goal (also known as a PHG) for perchlorate and the human health risk assessment process used to derive the public health goal. The public health goal will be used by the California Department of Health Services to set a drinking water standard. The state currently uses a range of 2-6 µg/l to regulate public drinking water supplies. No national drinking water standard for perchlorate currently exists. The conference also included a presentation on perchlorate analysis which described a new analytical method that can detect perchlorate at concentrations as low as 0.5µg/l. This significantly improves the ability of regulatory agencies to monitor this contaminant. For more information about this conference please see the GRAC website at www.grac.org.

The Torres Martinez Desert Cahuilla Indian Tribe and EPA Region 9 organized and hosted the conference addressing tribal concerns on perchlorate. The conference was held on the Colorado River Indian Tribe Reservation. Among the most interesting topics discussed at this conference was the remediation of the Kerr-McGee site in Henderson, Nevada and the effect of the contamination from that facility on the Colorado River. Releases from this facility have migrated to Las Vegas Wash and reached the Colorado River resulting in perchlorate concentrations up to 10µg/l. This has major implications for irrigation of food crops such as winter lettuce which can absorb and concentrate perchlorate and for the tribes who depend upon the Colorado River. Please see www.tribalwater.net for more information about this event.

If you would like more information on perchlorate contamination, please contact Stephanie Sanford at 541-737-5861 or stephanie.sanford@oregonstate.edu.