More studies sought on perchlorate

Thursday, June 15, 2000 | 10:57 a.m.

The American Water Works Association is calling for more studies on the effect on human health from the rocket fuel booster perchlorate after an Arizona researcher discovered four Yuma infants with over-active thyroids.

Dr. Ross Brechner presented his research today on ammonium perchlorate contaminating the Colorado River that serves 20 million people downstream of two industrial plants in Southern Nevada that have produced millions of pounds of the salt for more than 50 years.

Newborns of mothers from Yuma exposed to perchlorate had "significantly higher" levels of a thyroid-stimulating hormone than infants of non-exposed mothers from Flagstaff, the study found. In fact, the Flagstaff infants did not show increased hormone activity.

Brechner's study is the first time health effects have been linked from such low doses of the chemical to pregnant women drinking water, association spokesman Douglas Marsano said from Denver at the water works association's annual meeting.

"The results clearly warrant further study," Marsano said.

Brechner studied blood tests from infants in Yuma, where residents rely on the river for drinking water, and others in Flagstaff, which has an independent water source. He is chief of the Arizona Department of Health Services' Office of Epidemiology and Statistics in Phoenix.

From October 1994 through August 1999 the Arizona Newborn Screening Program reported four cases of hypothyroidism in Yuma newborns, Brechner reported. The study included 7,599 newborns from Yuma and 3,539 infants from Flagstaff.

The data demonstrated an association between low-level perchlorate exposure, he said. "It does not seem prudent to assume that the observed changes in neonatal thyroid function are harmless," Brechner said.

"In addition, appropriate interventions to limit human exposure to perchlorate should be undertaken," the study concluded.

The U.S. Environmental Protection Agency tested Yuma's water in August 1999 and found 6 parts per billion in the drinking water, according to Kevin Mayer of the EPA's Superfund Site Cleanup Branch.

The latest level of perchlorate in Lake Mead was 11 parts per billion, according to the Southern Nevada Water Authority.

There is no federal or state drinking water limit for perchlorate. California set a guideline of 18 parts per billion in 1997.

Although it was an ecological study, Brechner said that perchlorate contamination is not removed by treating water with carbon filters or conventional water treatment plants.

Perchlorate competes with iodine in the thyroid. The chemical easily crosses the placenta in the womb and can cause over-active thyroid activity in both fetuses and the newborn, he said.

Some potential harm to the thyroid in fetuses can hinder nerve development, normal movement, fine motor skills and cause abnormal vision, hearing and speech.

Other recent studies suggest that there are no harmful effects from ammonium perchlorate exposure on human thyroids.