PERCHLORATE LEVELS STUMP RESEARCHERS STATE, FEDERAL AGENCIES CAN'T AGREE ON WHAT'S SAFE IN WATER.

Byline: ALEX DOBUZINSKIS Staff Writer

Researchers know the rocket fuel component perchlorate can be harmful to humans, they just can't agree on how much of it makes drinking water unsafe.

State and federal agencies have set different levels, and environmental groups have battled industry over the science of understanding perchlorate's health effects.

The debate is important to Santa Clarita, which has the 996-acre Whittaker-Bermite property in the center of town, a site with high levels of perchlorate from decades of munition manufacturing.

Several years ago, environmentalists expressed concern that perchlorate could be a carcinogen. But research has found little evidence of that in humans. Instead, researchers have focused on the effects on the thyroid and the intake of iodine, which could affect pregnant women and fetuses.

California, the National Academy of Sciences and Massachusetts have all used a 2002 study that tested the effects of perchlorate on humans. But they came to different results.

California in 2004 set 6parts per billion as a goal for how much perchlorate should be tolerated in drinking water, although the state is still formulating an enforceable standard.

Massachusetts last year set the nation's first enforceable drinking water standard for perchlorate at 2parts per billion. And the U.S. Environmental Protection Agency, which a few years ago was considering a standard of 1part per billion, revised its assessment based on a National Academy of Sciences study. The EPA considers anything below 24.5parts per billion a safe level, but it has no enforceable standard.

The science is complicated by the fact that perchlorate could have little effect on a healthy adult man, but a permanently damaging effect on a fetus or infant's IQ level.

``The biggest concern was in the pregnant women because of the exposure of the fetus, and then a few weeks after birth, babies who are nursing,'' said Richard Johnston, who led a National Academy of Sciences study released in 2005. ``So that's a population you worry about most because of the effect on brain development.''

Ethical constraints prevent subjecting pregnant women to doses of perchlorate for research purposes, and using animals as test subjects has been controversial because animals' perchlorate reactions may be different from humans'.

The 2002 Greer study, which has been used by California, the National Academy of Sciences and Massachusetts, used healthy adults as subjects.

To adjust for vulnerable populations of pregnant women and fetuses, the National Academy of Sciences divided the level of perchlorate it would expect to affect a healthy human by a factor of 10. That resulted in the finding that 24.5parts per billion should be the limit for perchlorate in drinking water.

But a Centers for Disease Control and Prevention study released last year suggests it could take less perchlorate than that to harm pregnant women and their fetuses, especially those with low iodine levels.

The nonprofit Environmental Working Group has translated the amount of perchlorate identified in the CDC study as potentially harmful as 5parts per billion.

California officials are aware of the findings.

``It's not unusual for new studies to come out and produce important new information on chemicals,'' said Allan Hirsch, a spokesman for the California Office of Environmental Health Hazard Assessment. ``That's why we're supposed to review our public health goal periodically for every drinking water contaminant.''

Sujatha Jahagirdar, a clean water advocate for Environment California, said the state should not adopt 6parts per billion as an enforceable health standard when the CDC study indicates that might not be strict enough.

``My perception of that decision is it's prioritizing bureaucracy over health,'' she said. ``It's incredibly flawed public policy, and I think people should be outraged that the system that is set up to protect people's quality of water is failing.''

As for Johnston, he said the CDC study is not necessarily proof that perchlorate is more of a health risk. Instead, it shows pregnant women should take a prenatal vitamin with iodine, to avoid the health effects of low iodine levels, he said.

Environmental groups criticized the National Academy of Sciences report, arguing that industry groups had too much influence on the research. Many environmental groups continue to call for a standard of 1part per billion.

The debate rages on, as the California Department of Health Services works on determining whether the level of 6parts per billion is economically feasible to enforce as a standard, since cleanup of a site can cost millions of dollars.

alex.dobuzinskis(at)dailynews.com

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