Perchlorate may be acceptable in drinking water at levels higher that the current public health goal

Main Category: Public Health
Article Date: 09 Jun 2004 - 5:00 PDT

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Even at significantly higher levels than recommended by the state's leading health assessment agency, the contaminant perchlorate in drinking water seems to pose no additional risks to healthy people, according to a recent report issued by the UC Irvine Urban Water Research Center.

The center reached this conclusion following a broad review of existing research on the rocket fuel manufacturing byproduct. Produced by an independent committee of scholars, the center's report is being provided to the California Department of Health Services and other policymakers as they wrestle with setting a statewide standard for perchlorate in drinking water.

The committee viewed the Office of Environmental Health Hazard Assessment's current public health goal of 6 parts per billion as well reasoned and in keeping with a value set only on health considerations. Its findings, however, show that exposure to perchlorate at levels below 100 parts per billion would still protect the public health.

Perchlorate - a byproduct of rocket fuel manufacturing that was discharged as waste into groundwater supplies from defense sites - is a chemical that interferes with the normal function of the thyroid gland. In adults and children, the thyroid helps regulate metabolism. In children, it also plays a major role in proper development. Impaired thyroid function in expectant mothers may affect the fetus and newborn. Treatment of rats with other chemicals that result in chronic lowering of thyroid hormones has been shown to produce thyroid gland tumors.

"Clearly more research should be conducted related to exposure to perchlorate, particularly with pregnant women and other susceptible individuals," said committee member Ronald Shank, a UCI professor and chair of community and environmental medicine. "But we found no evidence in the current studies that demonstrate a difference in health effects in healthy individuals between low levels of perchlorate, such as the 6 ppb public health goal, and a level 10 times higher."

Perchlorate has been found throughout California in approximately 350 wells in 89 water systems; 90 percent of these are located in Southern California. Los Angeles, Orange, San Bernadino and Riverside counties report 40 to 89 percent of the water systems tested contain perchlorate levels greater than 6 ppb.

The URWC convened a committee of scholars in consultation with state health officials, environmental health scientists, toxicologists, engineers and economists to determine the nature and the effect of different standard levels on human health, California's water supplies, the types of treatment available, and the cost of compliance. The committee's charge was to examine the information available on all aspects of the contaminant and determine what is in the best interests of the state, its people and its water supply.

According to Betty Olson, interim director of the UWRC, the processes involved in standard setting are often difficult, requiring the weighing of health concerns against cost of treatment and availability of water.

The UWRC committee looked at the same information that will be considered by state health officials, but without the same legislative constraints, including:

• Distribution and concentration of perchlorate in California's water supplies

• Capacity to accurately, and at reasonable cost, measure percholorate in drinking water

• Public health goal

• Cost, as known to date, to treat contaminated supplies

• Contribution from food

• Benefit of treating water to remove perchlorate achieved at different levels.

A copy of the UWRC report is available at www.urban-water.uci.edu/index.asp

The UWRC committee was comprised of Richard Bull, adjunct professor of pharmacology/toxicology and environmental science at Washington State University and former director of the U.S. EPA's Toxicology and Microbiology Division; Andrew Chang, professor of agricultural engineering and associate director of the UC Center for Water Resources at UC Riverside; Carl Cranor, professor of philosophy, UC Riverside; Ronald Shank, professor and chair of community and environmental toxicology, UCI College of Medicine; and Rhodes Trussell, adjunct professor of environmental health, science and policy at UCI and president of Trussell Technologies.

The UCI Urban Water Research Center promotes increased understanding of urban water issues in order to assist local, state and federal agencies with their efforts to promote health, to enhance the efficient and fair use of water resources and to protect the environment. The center considers the entire urban water system, including water use, water economics and the institutional systems.

About the University of California, Irvine: The University of California, Irvine is a top-ranked public university dedicated to research, scholarship and community. Founded in 1965, UCI is among the fastest-growing University of California campuses, with approximately 24,000 undergraduate and graduate students and about 1,300 faculty members. The third-largest employer in dynamic Orange County, UCI contributes an annual economic impact of $3 billion.