California Panel Softpedals Perchlorate Risk

IRVINE, California, June 9, 2004 (ENS) - The contaminant perchlorate in drinking water "seems to pose no additional risks to healthy people" even at higher levels than recommended by the state of California, according to a new report issued Tuesday by the University of California-Irvine Urban Water Research Center.

The Urban Water Research Center reached its "no additional risk" conclusion following a review of existing research on perchlorate. The Center is providing the report, produced by a five member committee of scholars, to the California Department of Health Services and other policymakers as they work towards setting a statewide standard for perchlorate in drinking water.

Perchlorate is a byproduct of rocket fuel manufacturing that was discharged as waste into groundwater supplies from defense sites, and has been a source of conflict in California, where it has been detected in 89 water systems.

There are three major sources of perchlorate in the United States - ammonium perchlorate is used as an oxidizer in solid rocket propellant, sodium perchlorate is used in slurry explosives, and potassium perchlorate is used in road flares and air bag inflation systems. Manufacturing wastes and improper disposal of chemicals containing perchlorate are increasingly being discovered in soil and water.

Researchers differ on how much perchlorate is safe to drink. (Photo courtesy EPH)

More than 20 million Americans in 24 states drink water contaminated with perchlorate, and contamination is suspected in 19 other states.

"Perchlorate has been shown to be absorbed into crops from irrigation water or other sources," the committee reports.

Perchlorate has been found throughout California in approximately 350 wells in the 89 water systems. Ninety 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 six parts per billion (ppb). This figure is the current official public health safety level for the contaminant, known as a goal, issued by the California Office of Environmental Health Hazard Assessment.

The committee found that exposure to perchlorate at levels up to 100 parts per billion "would still protect the public health," although the panel said in its report that this concentration "may not protect pregnant women and the normal development of their offspring, because of a number of uncertainties that are present in the database."

The U.S. Environmental Protection Agency (EPA) draft reference dose is one part per billion, a value which the aerospace companies view as overly restrictive.

“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 professor and chair of community and environmental medicine at the University of California-Irvine College of 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 six ppb public health goal, and a level 10 times higher,” Shank said.

The five member committee viewed the Office of Environmental Health Hazard Assessment’s current public health goal of six parts per billion as "well reasoned and in keeping with a value set only on health considerations."

In Santa Clarita, California the U.S. Army Corps of Engineers is working to remediate a perchlorate contaminated site that for 60 years has been used by companies making dynamite, ammunition, rockets, practice bombs and Sidewinder missiles. (Photo courtesy USACE)

California, Nevada and Arizona would likely be the states most impacted, the companies said.

"Overly strict standards would in effect create a 'problem' where one does not really exist, forcing citizens, industry and government to incur significant expenses for new treatment plants, retrofitting existing treatment plants, purchasing additional water supplies, lowering reservoir levels and pumping more groundwater from existing sources."

This would "contribute to a significant water shortage crisis as water supplies are closed because they do not meet the new standards," the companies said.

Questions have been raised about the impartiality of one of the Urban Water Research Center committee members - Richard Bull, adjunct professor of pharmacology/toxicology and environmental science at Washington State University and former director of the U.S. Environmental Protection Agency’s Toxicology and Microbiology Division.

Also a member of the National Academy of Sciences (NAS) Committee to Assess the Health Implications of Perchlorate Ingestion that is currently preparing a report, Dr. Bull has consulted in the past for government and industry, including litigation support on trichloroethylene-related issues for a law firm representing the aerospace company Lockheed Martin.

On May 14, California's two U.S. senators questioned Bull's impartiality in a letter to National Academy of Sciences President Bruce Alberts.

Senators Barbara Boxer and Dianne Feinstein said that "records indicate that a financially interested party has funded two of the committee scientists, Dr. Richard Bull and Dr. Charles Capen. Dr. Bull's conflicts of interest were partially acknowledged only due to external pressure. Dr. Capen's reported relationship with Lockheed Martin remains unnoted. This raises serious issues about NAS review of conflict of interest, bias, and balance for this panel."

The senators wrote that even the "appearance of conflict of interest or bias undermines NAS's credibility," and asked that NAS "fully investigate and disclose and potential conflicts of interests of any panel member immediately."

"Perchlorate dissolves easily, moves quickly, and persists indefinitely," the senators wrote. "Even at low concentrations, perchlorate poses serious health threats, including impaired physical and brain development in fetuses and newborns."

The U.S. Environmental Protection Agency is expected to recommend a final Reference Dose for perchlorate in 2005 after the National Academy of Sciences committee report has been completed. The NAS report is expected in late summer 2004.

Guests visit Site 285 where the Air Force is testing a technology that selectively removes perchlorate from groundwater. May 14, 2003. (Photo courtesy Edwards Air Force Base)

The Air Force granted a waiver to test the new resin technology at Edwards because of persistence shown by the base’s Restoration Advisory Board (RAB).

"It was the RAB that kept our focus on these kinds of sites," said Robert Wood, director of environmental management for Edwards Air Force Base, which is a Superfund site. "Normally, until cleanup benchmarks for perchlorate were established, perchlorate would have gone untreated at Edwards. But the RAB made their concerns heard."

The experimental technology cost $800,000, said Wood.

The closest Edwards groundwater contamination to the drinking water production wells in North Edwards is the Site 285 perchlorate plume. The Site 285 treatment system, which was designed to capture the perchlorate plume during the ongoing treatability study, is currently capturing the plume and preventing it from moving toward North Edwards. This system will continue to operate this year while the technology is being fully evaluated.

A copy of the Urban Water Research Center report, "Perchlorate in Drinking Water: A Science and Policy Review," is available at: http://www.urban-water.uci.edu/index.asp

The National Academy of Sciences Committee to Assess the Health Implications of Perchlorate Ingestion is found at: http://www4.nas.edu/webcr.nsf/ProjectScopeDisplay/BEST-K-03-05-A?OpenDocument