[CPEO-MEF] Debate Rages Over Safe Levels Of Toxin for Adults and Infants

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Debate Rages Over Safe Levels
Of Toxin for Adults and Infants
By PETER WALDMAN
Staff Reporter of THE WALL STREET JOURNAL

Perchlorate is one of a newly recognized group of toxins called
endocrine disrupters -- chemicals such as dioxin and PCBs that can alter
hormonal balances and thus impede human reproduction and development.

The debate is over how much perchlorate causes harm, and whether fetuses
and infants are more susceptible than adults to perchlorate's effects at
very low doses.

The EPA, citing experiments on rats and epidemiological studies in
Arizona and California, says perchlorate is dangerous in drinking water
at levels above one part per billion. The Pentagon and defense industry,
citing human experiments and epidemiological studies in Chile, say
perchlorate is safe in drinking water below 200 ppb. Billions of dollars
in cleanup and liability costs may hang in the balance, since most
perchlorate plumes in the U.S., including the Colorado River, range
between four and 100 ppb.

In 1993, several defense contractors, backed by the Pentagon, created
the Perchlorate Study Group to research toxicity. The group's "goal,"
according to an internal document written in 1996 by GenCorp's Aerojet
subsidiary, was "to provide EPA with a scientific-based argument to
justify a higher [reference dose] and thus a more reasonable remediation
standard." The industry group has spent roughly $7 million on toxicity
studies.

Yet, as with other contentious toxins such as arsenic and lead, the more
information EPA scientists learned about perchlorate, the more they
worried about its effects. Their main concern focuses on changes found
in the brain size of laboratory rat pups exposed to low doses of
perchlorate in utero. Such changes in so-called brain morphometry
indicate perchlorate's thyroid effects may cause permanent neurological
damage -- in rats as well as people, the EPA says, because the thyroid
system works similarly in both species.

This article can be viewed at:
http://online.wsj.com/article_email/0,,SB1039997700166193,00.html

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