Second Thoughts on Perchlorate Study: National Academy Panel Scientists Wonder Why Some Reporters Got The Story Wrong

Last week, a National Academy of Sciences (NAS) panel released a long-awaited report on health effects of the toxic rocket fuel chemical perchlorate. Some of the U.S. news media reported the NAS found the chemical is dramatically safer than previously thought, so Americans shouldn't be too worried about its widespread occurrence in drinking water supplies.

Since its release, NAS panel members have made it clear their findings do not set safe drinking water levels of perchlorate, which can disrupt production of thyroid hormones needed for growth and development. They say other factors - the heightened risk to infants and the added presence of perchlorate in milk and food - must be considered that would result in a drinking water standard nearly as low as any proposed or adopted by federal or state regulators.

Evidence that many reporters got the perchlorate story wrong comes from several sources...

• An e-mail, obtained by the Environmental Working Group (EWG), from the NAS panel chairman to California health scientists, saying "[O]ur recommendation dealt with a dose from all sources . . . and this should be corrected for the weight of the individual." He said he tried to set the record straight "when we saw how often the press got it wrong," but by then most stories had been published or broadcast.
• A memo from the American Water Works Association advising its 4,700 member utilities that a drinking water standard based on the NAS findings could be as low as 1.7 parts per billon (ppb) - almost identical to the standard proposed by Massachusetts, the most stringent perchlorate standard proposed anywhere.
• A public radio interview in which a scientist from the NAS panel, asked if the findings must be adjusted to reflect infants' lower body weight and additional perchlorate exposures besides drinking water, replied: "[A]bsolutely correct."

EWG has also analyzed dozens of news reports about the study to determine where mistakes were made and why. Our analysis suggests that at least some of the blame falls to the Academy's press release, which said NAS recommended a reference dose (RfD) that was 23 times weaker than the reference dose in EPA's 2002 perchlorate risk assessment.

Based on that recommendation, many reporters calculated on their own that a drinking water standard would also be 20 or more times higher than the EPA had recommended. But there were problems with that approach:

• EPA never recommended a drinking water standard. The 1 ppb widely reported as the EPA "standard" was actually a hypothetical extrapolation from the Agency's RfD - without the consideration of added factors.
• Many reporters didn't seem to understand, and the NAS release did not explain, the differences between a drinking water standard and a reference dose. An RfD is the safe level per unit of body weight, and the level considered safe to consume from all sources. By law, drinking water standards must consider the lower body weight of infants, and when exposure comes from additional sources, a drinking water standard is set lower to keep overall levels down.

EWG has written to the NAS, requesting that they issue a statement clarifying their findings for federal and state regulators who will set drinking water standards.

"Perchlorate polluters have already begun a PR and lobbying campaign to persuade the public, elected officials and regulators that the Academy decided that higher levels of perchlorate in drinking water are safe for even infants and nursing mothers," EWG President Ken Cook wrote. "If the record isn't set straight, we could end up with standards that leave millions of people at risk."

MORE IMPORTANT PERCHLORATE NEWS AND INFORMATION

Academy Succumbs to Pentagon-White House-Industry Pressure, Recommends Perchlorate Safety Level That Fails to Protect Children / NRDC Says Recommendation to Add Iodide to Prenatal Vitamins Is "Too Little, Too Late"

Report Assesses Health Implications of Perchlorate Exposure

White House and Pentagon Bias National Academy Perchlorate Report

Perchlorate Coverage at Mary Shomon's Thyroid Site at About.com

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Source: Environmental Working Group