RESEARCH TRIANGLE PARK, North Carolina, August 25, 2010 (ENS) - Male rats exposed before birth to low doses of the weedkiller atrazine are more likely to develop prostate inflammation and to go through puberty later than non-exposed animals, finds a new study conducted by federal government scientists.
One of the most common agricultural herbicides in the United States, some 80 million pounds of atrazine are applied across the country every year to control broadleaf and grassy weeds in crops such as corn and sugar cane. It is the main ingredient in about 40 name-brand herbicides.
"Atrazine is a staple product for producers, who use it as a critical tool for weed control in growing the vast majority of corn, sorghum and sugarcane in the United States. Use of atrazine fights weed resistance, reduces soil erosion and increases crop yield," according to the Triazine Network, an association of growers and researchers.
But atrazine and its byproducts are known to be endocrine disrupters that are persistent in the environment, making their way into both surface water and groundwater supplies.
This study on how atrazine affects male rats was led by Suzanne Fenton, PhD, and Jason Stanko, PhD, of the National Institute of Environmental Health Sciences, part of the National Institutes of Health. The scientists tested male rats using atrazine concentrations close to the regulated levels in drinking water sources.
The current maximum contamination level of atrazine allowed in drinking water is three parts per billion.
"We didn't expect to see these kinds of effects at such low levels," Fenton said, releasing the findings Tuesday.
Dr. Fenton, a reproductive endocrinologist, will be presenting the research findings in September to the U.S. Environmental Protection Agency, as part of its ongoing reassessment of atrazine.
In 2009, the EPA began a comprehensive new evaluation of atrazine to determine its effects on humans. At the end of this process, in September 2010, the agency has said it will decide whether to revise its current risk assessment of atrazine and whether new restrictions are necessary to better protect public health.
This is the third time since the early 1990s the EPA has evaluated atrazine. In each of the two previous reviews the EPA ruled in atrazine's favor, most recently in 2006 after considering 6,000 studies and 80,000 public comments...
Professor Tyrone Hayes in the Department of Integrative Biology at the University of California, Berkeley, who specializes in the study of atrazine, calls the chemical, "a potent endocrine disruptor with ill effects in wildlife, laboratory animals and humans."
"Atrazine chemically castrates and feminizes wildlife and reduces immune function in both wildlife and laboratory rodents," says Hayes, who has published research showing that exposure to atrazine caused male tadpoles to turn into hermaphrodites - frogs with both male and female sexual characteristics.
"Atrazine induces breast and prostate cancer, retards mammary development and induces abortion in laboratory rodents," Hayes warns. "Studies in human populations and cell and tissue studies suggest that atrazine poses similar threats to humans."
Other scientists support the use of atrazine when it is used correctly. Purdue University weed scientist Bill Johnson says, "Farmers need to understand both the rate restrictions of atrazine for different soil types and the setbacks from water sources. Like any chemical, they shouldn't apply atrazine right before a big rain in order to prevent runoff."
...March, 16 communities in six Midwestern states filed a federal lawsuit seeking to force atrazine manufacturer, the Swiss company Syngenta, to pay for removal of the herbicide from their drinking water. The class action lawsuit was filed in U.S. District Court for the Southern District of Illinois by 16 towns and villages in Kansas, Illinois, Indiana, Ohio, Missouri, and Iowa.
Atrazine has been banned in Europe, even in Switzerland, the home of manufacturer Syngenta.