Perchlorate in food
JUPITERIMAGES
Utiger of the Harvard Institute of Medicine. Although some lawmakers and Food is the primary source of perthe U.S. between 2003 and 2006. environmental groups argue that chlorate for most Americans, and To estimate exposure, they the new study emphasizes the U.S. toddlers on average are becombined the analytical results need for a national drinking-water ing exposed to more than half of with food consumption estimates. standard, EPA has not declared its the U.S. EPA’s safe dose from food Drinking water was excluded from intentions. alone, according to a new U.S. Food the survey. The Safe Drinking Water Act and Drug Administration (FDA) Other studies have found perrequires that a contaminant be diet survey designed to provide chlorate in food, but this is the capable of causing adverse health perchlorate and iodine intake avfirst to estimate exposure for the effects and occur in public water erages from food for the systems at a frequenentire U.S. Even though cy and level of publicthe new study is silent on health concern. intake by highly exposed In addition, the propopulations, several posed regulation must lawmakers and environ provide a meaningful mental advocates renew opportunity for reducing their calls for a national health risks, says Alan perchlorate drinking-waRoberson, director of ter standard, but EPA is regulatory affairs at the not divulging its plans. American Water Works The agency, which has Association. been waiting for the reEPA is considersults from the FDA study ing health effects studto help it decide whether ies published after the to set a national drinkNAS study, according-water standard for ing to a May 2007 Fedperchlorate, intends to Dairy products are the major source of perchlorate for children. eral Register notice (72, issue a preliminary de24,016–24,058). termination on whether to regulate U.S. population. Toxicologist Gary These include the CDC study, the substance soon, according to Ginsberg of the Connecticut Dewhich found that women with low Benjamin Grumbles, assistant adpartment of Public Health notes iodine levels who are exposed to ministrator of EPA’s Office of Wathat the FDA estimates for adult perchlorate may have impaired ter. EPA has been investigating the exposure to perchlorate from food, thyroid function even when their contaminant for almost a decade. about 10% of the reference dose, exposure level is below the EPA Perchlorate is well known as a agree well with biomonitoring safe dose. major component in rocket fuel, data collected by the Centers for Perchlorate has been found in but the chemical also forms natuDisease Control and Prevention drinking water from 4% of major rally. In sufficient amounts it dis(CDC). But the FDA survey cannot water supply systems in 28 states rupts the thyroid by inhibiting the estimate extremes of exposure. at levels of at least 4 parts per biluptake of iodide, an essential com“The CDC study found a 4-fold lion (ppb). Scientists with the ponent of thyroid hormones. Beincrease from the average to the Environmental Working Group cause these hormones direct brain extremely exposed. . . . If this holds calculate that perchlorate concendevelopment, health concerns for toddlers, then some are likely trations in drinking water would have focused on fetuses and young to be way above the safe dose,” he need to be lower than 2 ppb to infants. says. keep toddlers’ exposure below the A National Academy of Sciences FDA toxicologist and study ausafe-dose level. (NAS) committee in 2005 recomthor Michael Bolger acknowledges As for providing a meaningful mended a safe dose of 0.7 microthat the survey on its own provides opportunity to reduce health risks, grams per kilogram of body weight no information about the distribuGinsberg notes that water compaper day, and EPA adopted this as tion of perchlorate exposures. nies know how to get perchlorate its reference dose. For iodine, the FDA study has out of drinking water. As part of FDA’s existing Total similar limitations. CDC data indi“But we really don’t know how Diet Study, agency scientists meacate that about one-third of Amerito get perchlorate out of food. By sured perchlorate levels in 285 foods can women are deficient in iodine. getting it out of the water we can obtained from grocery stores and “But those people don’t show up reduce the health risk,” he adds. fast-food outlets in different parts of in the FDA study,” says Robert —REBECCA RENNER March 15, 2008 / Environmental Science & Technology ■ 1817
