By Sean Henahan, Access Excellence

CHAMPAIGN, Ill.- Atrazine, a common agricultural herbicide that often makes its way into US drinking water rapidly causes chromosomal damage in test animals at exposure levels below those established by the EPA as safe, according to researchers at the University of Illinois.

Using a technique called flow cytometry, a method of monitoring molecular changes, a team of researchers tested concentrations of atrazine in 135 surface water sources in Illinois. Atrazine was detected in 114 of these sites. Thirty-four sites had concentrations at or above the EPA maximum contaminant level of 3 parts per billion, according to the study by A.G. Taylor of the Illinois EPA.

"The results provide evidence for further investigations as to the potential health risk of consuming water contaminated with atrazine," writes U. of I. cytogeneticist A. Lane Rayburn in an article accepted for publication in the Journal of Environmental Quality. Chromosomal breakages, which cause structural changes in DNA, have been associated with some forms of cancer and birth defects.

A study by Dr. Rayburn's team showed that exposure of the ovary tissues of hamsters to even relatively low concentrations of atrazine caused chromosomal breakage within two days. Their data shows chromosomes with breaks in size and a skewing of distribution peaks. Previous studies that found chromosomal damage and links to cancer were based on high levels of exposure not normally found in the environment.

"This research shows a potential that these low levels can cause chromosomal damage, and we need to proceed to the next step -- the testing of human tissues to see if the same thing happens at low levels of exposure through drinking water," Rayburn said. "People could say that what we are seeing are small breaks, perhaps even insignificant, but keep in mind that these studies involved exposure for just 48 hours. Over time, these breakages potentially could grow. For now, however, we do not know what the results of these breakages would be. "

Atrazine, first registered for use in 1959, is under review by the EPA because of health concerns of exposure through food and water. At high levels it has been found to cause cancer in rats. Atrazine is widely used on corn, sorghum, sugar cane, wheat fallow, macadamia nuts, guava and turf grass to control certain weeds. The Corn Belt accounts for 50 percent of its use. Only certified users may apply atrazine.

Rayburn and Biradar also tested the herbicides bentazon and simazine; neither caused measurable chromosomal damage. The studies were funded by the Illinois Groundwater Consortium. Farmers use 64 million to 80 million pounds of atrazine a year, according to the U.S. Environmental Protection Agency.