by Mitchell Clute
The Environmental Protection Agency has declined to set allowable levels for perchlorate contamination of drinking water. Instead, the agency called for the National Academy of Sciences to conduct a further study of the toxic rocket fuel component.
The chemical is especially dangerous to children and developing fetuses because perchlorate blocks the thyroid's uptake of iodine, which is a key building block of thyroid hormone.
"Our primary concern with perchlorate is its effect on the thyroid gland," said Anila Jacob, a senior scientist with the Environmental Working Group, based in Washinton, D.C. "We know from studies that one-third of American women have lower iodine levels, so perchlorate exposure is especially problematic during pregnancy, because women need adequate levels of thyroid to ensure brain development in the fetus."
EPA critics suggest that the failure to regulate perchlorate levels is a result of pressure from the White House and Defense Department in an attempt to protect the defense, aerospace and chemical industries. Manufacturers and users of perchlorate would likely be liable for millions in clean-up costs if contamination levels were adopted.
"EPA has dragged its feet for so long on this issue that Congress has introduced bills in both the House and Senate to force EPA to adopt a drinking water standard," Jacob says. "We are hopeful that the new administration will be more proactive about this issue."
The issue marks a battle between long-term EPA scientists who advocate regulation and White House officials who oppose it. Last September, the Washington Post obtained the EPA's "preliminary regulatory determination" on perchlorate. The document, heavily edited by the Office of Management and Budget, assumed maximum allowable levels of 15 parts per billion, versus 1 ppb in EPA documents released in 2002.
Even with this higher limit, the document suggests the more than 16 million people are exposed to unsafe levels of perchlorate. The document also found that if parents were to mix formula with water containing perchlorate levels of 15 ppb, infants would receive more than five times the level deemed safe.
"Two states have already set drinking water standards," said Jacob. "Massachusetts has a standard of 2 ppb, and California a standard of 6 ppb. We'd like to go as low as the technology will allow, which is 1 ppb. There is widespread exposure across the U.S. population, and this exposure needs to be regulated."