Tap water in the U.S., particularly in the agricultural regions of the Midwest, comes tainted with a weed killer called atrazine. The herbicide is spread across 75% of all U.S. cornfields and frequently turns up in surface and groundwater. The U.S. Environmental Protection Agency (EPA) has set a safety limit of 3 parts per billion of the chemical in drinking water, but a new study reveals that women’s hormone levels and menstrual cycles can be radically altered at far lower levels.Researchers compared women in Vermont (in towns without atrazine use) to those in Illinois (with high levels of atrazine use) and found that atrazine exposure in drinking water, even below the EPA’s standards, was associated with altered menstrual cycles and periods delayed by over six weeks, as well as lowered levels of reproductive hormones. Specifically, as reported in Environmental Health News, “The women from Illinois farm towns were nearly five times more likely to report irregular periods than the Vermont women, and more than six times as likely to go more than six weeks between periods. In addition, the Illinois women had significantly lower levels of estrogen during an important part of the menstrual cycle.”
The more tap water an Illinois woman drank, the more likely she was to have irregular periods. Most troubling was that levels of atrazine in the water in both states was well below the EPA’s established 3ppb standard. In the case of Illinois, tap water concentrations of atrazine averaged at 0.7ppb. While it is possible some other chemical is causing these hormonal changes, atrazine has been tied to such abnormalities before. Notes the article in Environmental Health News: “In 2009, a study tied atrazine in drinking water to low birth weight in Indiana newborns. And in a study of more than 3,000 women enrolled in the Agricultural Health Study, those who described using atrazine and other pesticides had an increased risk of missed periods and bleeding between periods.”
One researcher added that the hormonal changes in evidence could also impact a woman’s fertility, and they could play a role in diseases from osteoporosis to diabetes to cancer. Atrazine has been the subject of numerous studies as to its health impacts and has been banned in the European Union due to increasing evidence that it poses harm to both humans and wildlife. In fact, the herbicide appears to “affect development of the male reproductive system” in frogs, “decreasing fertility and in some cases leading to hermaphroditic frogs.” Despite growing concerns, use of the herbicide is on a steady climb in the U.S.