EPA Action On Perchlorate Gets Mixed Review

EPA’s safe daily dose for perchlorate of 24.5 ppb is protective of human health but fails to address an important public health issue, the agency’s inspector general says. EPA needs to determine the cumulative health risk from exposure to perchlorate and other chemicals that inhibit the uptake of iodine by the thyroid, the IG says in a Dec. 30, 2008, report. By lowering the amount of thyroid hormone, low iodine levels in pregnant and nursing women can impair brain development of their fetuses and infants. The IG criticized EPA for assessing the risk posed by perchlorate, a chemical used in rocket fuel and found in many public drinking water supplies, without considering other factors that restrain iodine uptake. EPA needs to assess the risks of perchlorate, along with these other factors: exposure to thiocyanate and nitrate—two chemicals that also hinder the uptake of iodine—and the lack of sufficient iodine in the diet, the IG says. EPA set the safe daily dose for perchlorate in February 2005, following the release of a National Research Council report that recommended the 24.5-ppb level.