Human exposure to atrazine is linked to a number of serious health effects. A potent endocrine disrupter, atrazine interferes with hormonal activity of animals and humans at extremely low doses.
Timing of exposure may be more important than exposure levels. Research shows that low levels of exposure during key periods of pregnancy may interfere with healthy fetal development. The third trimester of pregnancy appears to be most critical, says a recent epidemiological study. Synergystic effects between atrazine and other pesticides may also render health harms more severe.
Atrazine is one of the most widely used herbicides in the U.S., and is found in 94% of U.S drinking water tested by the USDA — more often than any other pesticide. An estimated 7 million people were exposed to atrazine in their drinking water between 1998 and 2003.
The highest levels of contamination are in the Midwest where it is widely used on corn fields. USGS monitoring shows drinking water concentrations typically spike during the spring and early summer as rains flush the freshly applied herbicide into streams — and into local water supplies.
Data from the EPA's Atrazine Monitoring Program show that atrazine levels in drinking water can spike above the legal limit of 3 parts per billion in some U.S. water supplies. Although the EPA bases its limit on an annual average (not seasonal peaks), the monitoring results reveal alarming levels of human exposure.
According to NRDC's 2010 analysis of the most recent EPA data, drinking water in 67 public systems had peak atrazine levels above 3 parts per billion (ppb), with one as high as 60 ppb in Ohio. Six water systems had average annual atrazine concentrations that exceeded the EPA limit entirely. And these figures are for treated drinking water — raw water samples contained even higher concentrations. (See also NRDC's 2009 Poisoning the Well)
Exposure to atrazine does not kill right away. For sensitive species however, atrazine's sublethal effects can be almost as devestating.
Fish and amphibians are most vulnerable. A growing body of research shows that atrazine exposure--even to trace levels of the herbicide--can adversely impact a number of species. Tyrone Hayes and other scientists have conducted research to show that exposing frogs to as little as 0.1 parts per billion can cause severe health effects, including a kind of chemical castration. Atrazine exposure from contaminated surface water is also known to compromise fish and amphibian growth, behavior, immune function, and gonadal development. Hayes recently found that 10% of male frogs reared in atrazine laced water turned completely into females. Strikingly, the level of atrazine used in the study — 2.5 ppb — is less than the EPA limit for drinking water contamination.
There are many viable ways of producing corn and growing food without relying on atrazine. According to recent analyses, dropping atrazine would result in yield losses of less than 1%, much lower than industry estimates.
Farmers in states like Minnesota are using innovative production systems to raise corn without atrazine. Since Germany and Italy banned atrazine in 1991, corn yields and acres of corn harvested have gone up, rather than down. Farm organizations such as the Land Stewardship Project have documented many ways to reduce and eliminate the use of atrazine in corn production.
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