It's been a bad week for Atrazine. The pesticide, used on 75 percent of the corn crops in the Midwest and now a common ingredient in ground and drinking water, has long been associated with birth defects in animals. Now, a new study has found that women who are exposed to Atrazine at levels considered safe are more likely to have irregular menstrual cycles and low estrogen levels.

Researchers compared women from farm towns in Illinois, where Atrazine in the drinking water is present at concentrations below the federal health standard of three parts per billion, to an equivalent group in Vermont, where it is rarely used. The women from Illinois were nearly five times more likely to report irregular periods and more than six times as likely to go more than six weeks between periods. The researchers also found that the Illinois women had less estrogen in their systems during a critical part of the menstrual cycle, raising questions about the pesticide's impact on fertility.
Women in Illinois who said they drank more than two cups of tap water daily reported an even greater occurrence of irregular periods.

According to a story in Environmental Health News , the researchers said he results, fit with studies on lab animals exposed to the herbicide, as well as with some limited research that reported human effects.

One study tied Atrazine in drinking water to low birth weight in Indiana newborns, and another of 3,000 women enrolled in the Agricultural Health Study found those exposed to Atrazine and other pesticides had an increased risk of missed periods and bleeding between periods. The Agricultural Health Study is a nationwide project sponsored by the National Institutes of Health.

On the animal front, this week a new review of the scientific data by 22 scientists, found consistent patterns of reproductive dysfunction in amphibians, fish, reptiles and mammals exposed to the chemical.
At least 10 studies found that exposure to Atrazine feminizes male frogs, sometimes to the point of sex reversal, a lead researcher said.

Atrazine was banned in the European Union in 2004 because of its persistent groundwater contamination. In the United States, however, Atrazine is one of the most widely used herbicides, with 76 million pounds of it applied each year.

But the agriculture and chemical industry points out there is an up side to Atrazine. At webcast press conference today held at the National Association of Farm Broadcasters convention in Kansas City, they highlighted just how important Atrazine is, not only for the farmers using it, but for the American economy -- an $18 to $22 billion benefit over five years, they said. Atrazine increases U.S. corn output by 600 million bushels per year, prevents 85 million metric tons of soil erosion annual, and cuts down on 280,000 metric tons of carbon dioxide per year.