Hazardous Waste: Perchlorate Debate Grows
Authors: Richard Dahl
Journal: Environmental Health Perspectives (2004)

The presence of a rocket-fuel component called perchlorate in drinking water sources around the nation has drawn the attention of scientists and public health advocates who say that even small doses of the chemical threaten people’s health. But the prospect of billions of dollars’ worth of cleanup bills landing on desks in the Pentagon and private industry has created a controversy that the National Academy of Sciences (NAS) has been called upon to help sort out.

The Department of Defense (DOD) and the National Aeronautics and Space Administration have been adding perchlorate to rocket fuel and munitions since the 1940s, and its use remains unregulated. Gina Solomon, a senior scientist at the Natural Resources Defense Council, points out that there is broad agreement that perchlorate interferes with the uptake of iodine into the thyroid gland as well as other tissues, including the placenta and mammary glands. The real danger of perchlorate-contaminated water, Solomon says, is the threat it poses to pregnant women, infants, and fetuses. Whereas adults have the reserve capacity to withstand a month or more with limited iodine intake, a fetus or infant can be harmed much more rapidly due to the reliance of the developing brain on adequate thyroid hormone levels.

The U.S. Environmental Protection Agency (EPA) started measuring for perchlorate as far back as the 1980s, but it wasn’t until the 1997 development of a new method to measure concentrations as low as 4 parts per billion (ppb) that the EPA and state environmental agencies were able to initiate serious examinations of the extent of perchlorate contamination of groundwater. According to the EPA, perchlorate had been detected in the groundwater of 33 states as of April 2004, and chemical users and manufacturers have been identified in more than 40.

In 1995, the EPA issued an interim guidance level of 4–18 ppb for perchlorate based on the limited data available at the time. Then, in 1998, the agency issued a draft health assessment based on studies submitted as part of a joint government testing strategy, and proposed a reference dose of 32 ppb. The external peer review that followed resulted in a recommendation for further testing.

When the EPA issued a revised risk assessment in 2002, it made things potentially much more onerous for the DOD and perchlorate manufacturers by suggesting a drinking water standard of 1 ppb or lower would be necessary to protect public health. In contrast, the Perchlorate Study Group, an industry consortium that has worked with the EPA and the DOD, proposed a much looser reference dose equivalent to 200 ppb.

With interested parties so far apart on their desired perchlorate limits, the Bush administration stepped in and called for the NAS to convene a panel to study the issue. A final report, which the EPA will consider as it finalizes its health assessment, is expected by the end of this year. In the meantime, the EPA is operating under the standing interim health guidance level of 4–18 ppb. Marianne Lamont Horinko, the agency’s assistant administrator for the Office of Solid Waste and Emergency Response, encouraged agency personnel in a 22 January 2003 memorandum to “carefully consider the low end” of that range.

A spokesman for the Perchlorate Study Group, Bill Romanelli, declined to comment on that group’s proposed reference dose while the NAS study is still ongoing. But he did say that group representatives had, in a 24 May 2004 meeting with the NAS panel, presented recent unpublished research that preliminarily concluded that a perchlorate level of 110 ppb had no effect on pregnant women and infants, and that levels as high as 10,000 ppb had no effect on healthy adults.

Even as the NAS study goes on, debate swirls. In a 14 May 2004 letter to NAS president Bruce Alberts, California senators Barbara Boxer and Dianne Feinstein questioned the appointment of panelists Richard Bull and Charles Capen, charging that defense contractor Lockheed Martin had funded both scientists in the past.

Some states are taking matters into their own hands. On 11 March 2004 the California EPA announced a goal of 6 ppb perchlorate in drinking water. The next step will be to establish an enforceable standard, which could take another year. Two months later, the Massachusetts Department of Environmental Protection proposed a cleanup guidance concentration of 1 ppb to address contamination in that state’s water.

Meanwhile, the perchlorate issue took another turn when the Environmental Working Group, a research and advocacy organization, conducted a study confirming earlier reports of perchlorate in some California-grown lettuce. Renee Sharp, an analyst with that group, points out that the Colorado River, which is polluted by perchlorate, irrigates 1.5 million acres in Arizona and Southern California, and the food grown there is shipped all over the country. “The whole food uptake issue makes it a much more widespread problem than if it was just a drinking water problem,” she says. “The drinking water problem itself is pretty enormous, but the food makes it even bigger.”