Chemical in Water May Cause Thyroid Troubles

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Thursday August 10 10:34 AM ET

Chemical in Water May Cause Thyroid Troubles

NEW YORK (Reuters Health) - Drinking water contaminated with low

levels of perchlorate--a chemical used in the production of rockets,

missiles, fireworks and matches--may be to blame for unusual thyroid

hormone levels in some Arizona newborns, results of a study suggest.

The chemical has made its way from disposal sites in Nevada into the

Colorado River system, which is a source of drinking water for about

20 million people in Arizona, California and Nevada, according to a

team of researchers led by Dr. Ross. J. Brechner, of the Arizona

Department of Health Services in Phoenix.

The amount of perchlorate that humans can consume without

experiencing any ill effects is uncertain. Ordinary water-treatment

plants cannot remove the chemical from the water supply.

The chemical is known to affect the function of the thyroid gland, so

Brechner's team decided to compare cases of thyroid problems in

children born in two Arizona cities--Yuma, where the water supply

contains perchlorate, and Flagstaff, where the water is perchlorate-

free.

Compared with infants born in Flagstaff, those born in Yuma had high

levels of hormones that stimulate the thyroid, which may indicate

that the thyroid is not functioning properly, Brechner and colleagues

report in the August issue of the Journal of Occupational and

Environmental Medicine.

The levels were still elevated even when the researchers took into

account factors that might have affected thyroid-stimulating

hormones, such as race, ethnicity and age at testing.

If not detected and treated promptly, thyroid problems may affect a

child's mental development, according to the report.

``We're not telling people to stop drinking the water,'' Brechner

told Reuters Health in an interview. There is not enough evidence to

prove that perchlorate in the water causes thyroid problems, he said.

``There is a statistical association between low-level contamination

with ammonium perchlorate and elevated or abnormal thyroid

function,'' Brechner said. ``We do not know the clinical significance

of this.''

He and his colleagues conclude that further research is needed to

measure levels of the chemical in the water supply and to confirm

whether it might cause health problems.

SOURCE: Journal of Occupational and Environmental Medicine

2000;42:777-

http://dailynews.yahoo.com/h/nm/20000810/hl/thyroid_1.html