Perchlorate's Risk Is Clear
Article Summary: Bottled spring water not being tested for perchlorate and that plain carbon filters remove little or no perchlorate (a chemical used in rocket fuels). Southern California --- particularly L.A. area --- has many military defense contractors, so many areas' groundwater has perchlorate contaminants (for example, Ventura County recently found it in its water).
(01-05) 22:32 PST (AP)
-- San Francisco Chronicle
Perchlorate's
risks clear, but not at what levels. The Associated Press
QUESTION: What is perchlorate?
ANSWER: Perchlorate is an oxygen-rich chemical used in rocket fuel and other explosives, including fireworks and flares. It easily dissolves in water and has been found to contaminate sites in 22 states where it was manufactured and handled. It is made up of chlorine and oxygen, and can combine with sodium, potassium or ammonium to form salts. Ammonium perchlorate is the form most frequently used in rocket fuel.
Q: Is perchlorate harmful?
A: The salt is a toxin, but there is disagreement about how much is bad for you when ingested. The U.S. Environmental Protection Agency is creating drinking water standards for the pollutant. "There's absolutely no question that it is a very big risk. The question is at what level do you avoid that risk?" said Kevin Mayer, the EPA's perchlorate coordinator for the Southwest.
Q: How does perchlorate affect human health?
A: Scientists know it interferes with the way the body takes iodide into the thyroid and can disrupt the gland's regulation of metabolism. In developing fetuses and newborns, iodine (the body reduces iodide to iodine) deficiency can cause mental retardation.
Q: Do any studies show it's harmful?
A: A 2000 Arizona study found an increase in abnormal thyroid levels in Yuma, Ariz., newborns whose mothers drank water from the Colorado River that contained five to seven parts per billion perchlorate. Dr. Ross Brechner, author of the study and now Maryland's state epidemiologist, said he could show only an association between perchlorate exposure and abnormal thyroid function. Further work is need, he said, but he said his personal recommendation would be that pregnant women be conservative and not drink the water.
Other perchlorate research, most of it funded by industry and the Pentagon, suggests moderate doses might not affect healthy adults. "At very low levels, I think levels below 200 parts per billion, you wouldn't have any effect on human health," said Dr. John Gibbs, medical director for former perchlorate manufacturer Kerr-McGee Corp.
Q: What are the standards for perchlorate in drinking water?
A: The EPA is considering a standard of one part per billion, which would be the equivalent of a grain of salt in an Olympic-sized pool.
Q: Is showering or bathing in contaminated water a threat?
A: No. The skin provides a barrier, the EPA's Mayer said.
Q: Is store-bought bottled water tested for perchlorate?
A: There is no state or federal requirement that bottled water be tested for perchlorate, although some bottlers can do so voluntarily. Mountain spring water is unlikely to contain the toxin. Tainted tap water that has been distilled or treated by reverse osmosis and then bottled is likely to be free of the toxin. Carbon filtering removes little or no perchlorate from polluted water, Mayer said.
Q: Should you avoid cooking with tap water if you suspect it contains perchlorate?
A: Cooking with perchlorate-laced
water poses the same risk as drinking. However, when food is cooked and drained,
any perchlorate would likely remain with the water, Mayer said.
