NRC Perchlorate Report Spurs Debate

A National Research Council (NRC) report on the health effects of perchlorate caused a stir in January.

A National Research Council (NRC) report on the health effects of perchlorate caused a stir in January.

Perchlorate is present in many public drinking-water supplies. In high doses, it can decrease the thyroid function in humans.

NRC said daily ingestion of up to 0.0007 milligrams per kilogram of body weight can occur without adversely affecting the health of even the most sensitive populations. That level is more than 20 times the “reference dose” that the Environmental Protection Agency proposed in a recent draft risk assessment.

NRC said perchlorate - a component of rocket fuel and fireworks - has been discovered in 35 states and more than 11 million people have perchlorate in their drinking water at concentrations of 4 parts per billion (ppb) or higher.

The most recent EPA risk assessment, published in 2002, proposes a daily reference dose of 0.00003 milligrams per kilogram (mg/kg) of body weight, which the agency said would correspond to a drinking-water concentration of 1 ppb based on certain assumptions about body weight and daily water consumption.

Jack Hoffbuhr, executive director of the American Water Works Association (AWWA), said, “Drinking water professionals have been researching the occurrence of perchlorate in water supplies and continue to pay close attention to relevant health effects research.”

He said AWWA is sponsoring a national perchlorate occurrence study that should yield data for the development of protective federal drinking water regulations. He also said the independent American Water Works Association Research Foundation (AwwaRF) has conducted several scientific studies on the presence and treatment of perchlorate.

The Natural Resources Defense Council (NRDC) charged that the White House, the Defense Department, and defense contractors collaborated to manipulate the NRC report.

Senior attorney Erik Olson said NRDC obtained documents through Freedom of Information Act lawsuits. He said, “We’ve never seen such a brazen campaign to pressure the NAS to downplay the hazards of a chemical, but it fits the pattern of this administration manipulating science at the expense of public health.”

NRDC charged the Defense Department has been blocking government efforts to address perchlorate pollution for more than a decade, but in the last few years, it has intensified its campaign in the face of new revelations about the chemical compound’s toxicity.

Sen. James Inhofe (R-Okla.), chairman of the Environment & Public Works Committee, noted that the study concluded adults can safely consume up to 20 parts per billion of perchlorate without experiencing health problems, about 20 times higher than the level in EPA’s risk assessment. The NAS reference dose includes a ten-fold safety factor for sensitive populations.

Inhofe said, “The NAS study clearly contradicts EPA’s risk assessment for perchlorate. I believe the study plainly shows that legislation forcing EPA to create standards for perchlorate in the very near future, as some environmental extremists are advocating, would be imprudent until a new risk assessment can be conducted reflecting the independently reviewed, sound science provided by the NAS.”

Arsenic Treatment Challenge Contest

The National Academy of Engineering (NAE) has established a $1 million prize for a practical technology to combat arsenic contamination of drinking water.

The Grainger Challenge Prize for Sustainability, funded by the Grainger Foundation, will be awarded for the development of a small-scale, inexpensive technique for reducing arsenic levels in drinking water.

NAE said arsenic-contaminated drinking water affects tens of millions of people, especially in developing countries where existing treatment technologies are too expensive for widespread use. It said treating drinking water with high levels of arsenic is not a major problem in the U.S. because many communities have the resources for expensive, centralized, and well-maintained water treatment facilities.

Alden Henderson of the U.S. Agency for Toxic Substances and Disease Registry, Atlanta, said: “Different solutions are required in the developing world, and the solution has to work in the field.”

NAE said a quarter of the population of Bangladesh drinks water from tube wells - a cheap, low-tech way of accessing groundwater. Many of the country’s estimated 10 million tube wells were built with international aid to provide an alternative to bacteria-tainted surface water. But they frequently tap into aquifers contaminated by arsenic from natural sources.

The Grainger Challenge Prize will go to a system with a low life-cycle cost. It must be robust, reliable, easily maintainable, socially acceptable, and affordable. As a sustainable technology, the system must also be within the manufacturing capabilities of a developing country and must not degrade other water quality characteristics or introduce pathogens.

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