[CPEO-MEF] Perchlorate: How much is too much?

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Perchlorate: How much is too much?
Research disparity delays federal safety standard

By KEVIN DENNEHY
STAFF WRITER
Helen Bresnahan can't say if chemicals in the water have aggravated her 
thyroid condition.

But these days, she wonders.

The retired teacher just knows that she's feeling more sluggish than 
before, weight doesn't come off as easily as it used to.
 
And she keeps hearing about this chemical called perchlorate, a 
substance that has been linked to thyroid conditions, and is creeping 
off nearby Camp Edwards toward the Bourne Water District water supply.

"I've only lived here since 1993, year round. I came from New Jersey, 
you know, the chemical state.

"But their water may be cleaner than what I've been drinking in this 
lovely part of the world," laments Bresnahan, who retired to a gray, 
shingled house with wide windows that overlook Phinneys Harbor.

Bresnahan is not the only one wondering if it's safe to drink water 
tainted by perchlorate. The confounding chemical has been discovered in 
water supplies from California to Cape Cod that serve more than 20 
million Americans.

But while millions of dollars have been spent on research over several 
years, there is still no answer to this question: How much perchlorate 
is too much?

Scientists know this much: Perchlorate affects the functions of the 
human thyroid.

In fact, until the mid-1960s, it was used to treat people with 
overactive thyroids.

If it's consumed by children, it can affect their growth rate, behavior, 
learning capability, even IQ level. For expectant mothers, it may 
influence how their fetus develops. In adults, it can alter metabolism 
rates.

And the federal Environmental Protection Agency recently confirmed that 
the chemical is a carcinogen, that at high enough levels it has caused 
tumors in lab animals.

Beyond that, there are more questions than answers.

Scientists disagree on just what dose would cause harm over a lifetime, 
or even during critical growth periods.

That means a federal standard won't likely be in place for years - 
frustrating news for communities such as Bourne, where the chemical was 
recently found at trace levels in three water supply wells. There simply 
isn't the magic number for safety that there is for other chemicals 
found in the cleanup of the Massachusetts Military Reservation, where 
the Air Force and Army will spend $1 billion to treat a series of 
contamination plumes caused by fuels, solvents and explosive materials.

This article can be viewed in its entirety at:
http://www.capecodonline.com/cctimes/perchloratehow23.htm

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