Perchlorate Goes From Obscurity To Point Of ControversyDec 14, 2002 | San Bernardino County Sun
It's a chlorine atom with four oxygen atoms attached.
It helps the space shuttle fly, air bags inflate and fireworks dazzle. It may also prevent babies from developing properly or cause problems for people with underactive thyroids.
Now perchlorate, once a household word only for rocket scientists, is the hottest topic in water pollution.
Ever since the California Department of Health Services developed a test in 1997 to detect tiny levels of perchlorate in water, scientists, regulators and researchers have been trying to find out how much of the salt is safe to drink.
There is disturbing evidence based on studies that even low levels of exposure can cause changes in thyroid function of children. But similar studies conducted in various locations don't always show a relationship.
The Colorado River is contaminated with perchlorate, and in one study, researchers compared the thyroid data of infants born in Yuma, Ariz., which relies heavily on the river water, with data from Flagstaff, Ariz., which gets no Colorado River water.
There appeared to be lower levels of thyroid function in the Yuma children compared with those in Flagstaff, though scientists warn the study has some major gaps in its data.
"It's hard to get good indisputable results,' said Kevin Mayer, who has long worked on the perchlorate issue for the U.S. Environmental Protection Agency.
Perchlorate's effects on the thyroid are well known. Indeed, it was used as a medicine for years to tame hyperactive thyroids.
This month, state officials in a draft proposal recommended a public-health goal of between 2 and 6 parts per billion. A public-health goal is the level at which regulators are reasonably certain there will be no ill effects after a lifetime of exposure.
The public may comment on the proposal through Jan. 24. A final number is expected to be adopted by spring.
But it's not a drinking-water standard. State officials expect to enact a maximum allowable level in water in 2004.
It seems the more that scientists look at the issue, the less perchlorate they want to see in the water. A previous recommendation in March suggested 6 parts per billion. The EPA has suggested 1 part per billion would be safe.
In another study, a UC Berkeley graduate student, Jackie Schwartz, looked at areas thought to have perchlorate contamination and then at data related to thyroid function in infants.
Again, there appeared to be a correlation between possible perchlorate exposure and reduced thyroid function.
Along with research on animals, those studies led the state this year to set a temporary "action level' of 4 parts per billion. A well that exceeds that level doesn't have to be shut down. Instead, local governments must be notified.
But most of the 75 wells in San Bernardino County in which perchlorate has been detected have been closed, or water is blended with other water to get the levels down.
Perchlorate is a problem because the thyroid relies on iodine for production of hormones that regulate the body's systems. And the salt behaves just like common table salt and readily dissolves in water, spreading easily.
But the molecule that carries iodine to the thyroid is much more attracted to perchlorate. It picks up the perchlorate instead of the iodine, reducing thyroid function.
"If pregnant women can't take up enough iodine, the fetus's brain development can be affected,' said Allan Hirsch, a spokesman for the state Office of Environmental Health Hazard Assessment, which made the health goal recommendation.
Mary Backus, 60, of Mentone was one of the early plaintiffs in a huge lawsuit against Lockheed Martin for allegedly contaminating the water beneath Mentone, Redlands and San Bernardino with perchlorate.
Both she and her 31-year-old daughter have thyroid problems, she says. But there's no way to know for sure if the water she drank is the culprit.
"I don't know if it's related,' she said.