Study looks at perchlorate

Low levels may have adverse effect on women

Las Vegas Review-Journal, Keith Rogers
Published October 4, 2006

Women may suffer adverse health effects after drinking water and eating food contaminated by low levels of the rocket-fuel ingredient perchlorate, a study released Wednesday by researchers for the Centers for Disease Control and Prevention found. The study showed that reduced functions of the thyroid gland "were significant and indicate that even small increases in perchlorate exposure may inhibit the thyroid's ability to absorb iodine from the bloodstream," according to the Web site of Environmental Health Perspectives, a monthly journal of peer-reviewed research. The study was the first of its kind based on examining urine and blood samples of 1,111 women. Researchers led by Benjamin C. Blount of the CDC's National Center for Environmental Health noted that they are planning another large study to confirm their findings. Their report doesn't necessarily represent the views of the CDC. For decades, perchlorate was produced by facilities in the Las Vegas Valley and used by the defense and space industry nationwide. It is currently found in Lake Mead and the valley's treated drinking water supply at low levels, 1.5 parts per billion, according to the Southern Nevada Water Authority. Nevada doesn't have a standard for perchlorate but based on guidance from the Environmental Protection Agency in 1999 the state has a "provisional action level" for groundwater that ranges between 4 parts per billion and 18 parts per billion. The CDC study focused on levels of nearly 3 parts per billion, which amounts to about a teaspoon of water in an Olympic-sized swimming pool. Perchlorate has been known to affect the thyroid at high levels. Prolonged exposures can reduce the amount of thyroid hormones that control the body's ability to break down food and produce energy and are essential to proper development of fetuses and infants. Perchlorate can also form naturally in the atmosphere and reach groundwater supplies in trace amounts from rain and snow, where it concentrates in such locations as west Texas and northern Chile. Blount's team had set out in 2001 to identify safe perchlorate exposure levels in sensitive people. They studied samples from 2,299 men and women who participated in the CDC's National Health and Nutrition Examination Survey as well as those from boys and girls who were at least 12 years old. Later, the team focused its research on women after observing more perchlorate effects in them than in men. A watchdog organization, the Environmental Working Group, based in Oakland, Calif., contends the new study means that 44 million American women who are pregnant, thyroid deficient or have low iodine levels are at a heightened risk from exposure to the chemical. The EPA has not yet set a federal drinking water standard for perchlorate but the agency has recommended a clean-up level of 24.5 parts per billion, or 250 times greater than what the Environmental Working Group says is acceptable for drinking water. The new study "really changes the debate ... and puts increased pressure on the EPA to set a stringent standard," Bill Walker, the group's vice president, said in a telephone interview. Massachusetts set the first drinking water standard for perchlorate in July at 2 parts per billion. California is considering a standard of 6 parts per billion. In an e-mail, Southern Nevada Water Authority spokesman J.C. Davis said the group's recommendations "are entirely inconsistent with those of the National Academy of Sciences and the Environmental Protection Agency. "If one were to follow the (Environmental Working Group's) perchlorate recommendation of 0.1 parts per billion, it could require municipal water agencies to stop chlorinating drinking water and collectively cost ratepayers billions of dollars for additional treatment with no established health benefits," Davis wrote.