Perchlorate Isn’t as Risky as Some Think, Study Says

Times Staff Writer

Perchlorate, a component of rocket fuel and munitions that has contaminated water supplies nationwide, may not be dangerous to people at the levels considered unhealthful by California scientists, a UC Irvine study says.

The chemical is known to affect the thyroid, and research, largely on laboratory rats, has led state and federal scientists to conclude that it could be dangerous even at low levels, particularly to pregnant women and young children.

But the UC Irvine study, which reviewed existing research, concluded that perchlorate at levels substantially higher than those considered harmful by California appeared to pose no health risk. In healthy adults, exposure to perchlorate in water at 100 parts per billion should not cause any hormonal effects, the study found. The report did not offer any conclusions about how pregnant women or people with thyroid problems would be affected at such levels.


Researchers at the state’s Environmental Protection Agency, by contrast, recently released a scientific assessment concluding that perchlorate could be dangerous at 6 parts per billion. That number, a “public health goal” that state scientists reached by reviewing much of the same data as UC Irvine, will serve as a basis for future drinking water standards. UC Irvine representatives said they planned to forward their findings to state officials to consider as they set such criteria.

The same day the UC Irvine report was released, one of its authors, toxicologist Richard Bull, was forced to resign from a National Academy of Sciences panel studying the health dangers of perchlorate.

Bull was a former paid expert for a law firm representing defense contractor Lockheed Martin, one of several aerospace firms responsible for much of the perchlorate pollution. His involvement with the study had been criticized by environmental groups and U.S. Sens. Dianne Feinstein and Barbara Boxer.

The national academy was asked by the federal government to look into the issue after the U.S. Environmental Protection Agency came out with a preliminary finding that perchlorate should be restricted to 1 part per billion in water supplies.

The Pentagon, which also is responsible for much of the perchlorate contamination around the country, strongly opposed the federal EPA’s conclusions and persuaded the White House to solicit the opinion of the National Academy of Sciences.

Representatives of the academy, which had initially defended Bull, said after his resignation this week that his work on the UC Irvine panel could lead others to believe he had already made up his mind on perchlorate. Academy officials confronted Bull after learning of the UC Irvine study, and he subsequently resigned, spokesman Bill Kearney said.


“We expect our committee members to come in with an open mind,” Kearney said.

Bull, a former director of the EPA’s toxicology and microbiology division, said he understood the concerns of the National Academy of Sciences.

“It’s the appearance that was the problem,” Bull said. “It was not the details, but the fact that I was associated with an opinion that put the NAS in an awkward position. I was not sensitive enough.”