Feb 05, 2010  |  ICGA

The study released today by the University of Washington, purporting to show a correlation between atrazine usage and the incidence of birth defects in Washington State, is simply not credible. This is especially true when this population-based survey is contrasted with the weight of scientific evidence. A large number of rigorous scientific animal studies have consistently shown that atrazine does not cause birth defects and does not cause reproductive effects.


Ecological studies, such as the one conducted by the UW researchers, make broad generalizations about environmental conditions and often overlook confounding factors. In fact, the UW study is not biologically plausible and provides no direct or credible link between atrazine and the kind of birth defect, gastroschisis, which it examined.  Media outlets jumping on this so-called science doesn’t help anyone.


The study's severe deficiencies are even more starkly revealed by the fact that atrazine usage in Washington State is minimal. The state has the second lowest amount of atrazine used by farmers in the United States, so the assumption that atrazine somehow causes more birth defects in Washington than in states with the highest use rates is random and doesn't follow sound logic.


Further, the study chooses an arbitrary distance of 25 kilometers (15.5 miles) from areas where atrazine had been detected without establishing how atrazine may have traveled to drinking water sources.  No community water system in the state of Washington has ever reported an atrazine drinking water notice of violation.


U.S. Geological Survey atrazine surface water monitoring data in the state of Washington (1993 to 2008) found that out of more than 1,400 samples, the maximum atrazine concentration reported was 1.4 ppb – less than half of the annual average exposure limit set by EPA.  More than 95% of the samples ranged from non-detectable to 0.05 ppb. This means that atrazine levels were essentially non-existent. 


In 2006, EPA looked at atrazine and determined it posed "no harm that would result to the general U.S. population, infants, children or other major identifiable subgroups of consumers."


Like this most recent report, many of these headline-grabbing studies are fundamentally flawed.  Scientists have long known that there are seasonal variations in birth defects in spring throughout the United States, even in states where atrazine isn't used.


Not only EPA, but governmental regulatory bodies and organizations around the world -- including the World Health Organization, Canada, the United Kingdom and Australia -- have recently examined atrazine and given it favorable reviews.


Most recently, the State of Minnesota conducted a thorough review of atrazine, and in a January announcement said, “The review finds that atrazine regulations protect human health and the environment in Minnesota.”


Farmers in the U.S. and around the world rely on atrazine for cost-effective, broadleaf weed control in corn, grain sorghum, sugar cane and other crops. EPA estimates that atrazine saves corn farmers $28 per acre in herbicide costs and yield advantages.


Data from the U.S. Department of Agriculture show that atrazine also is a widely used corn herbicide in conservation tillage systems, which can reduce soil erosion by as much as 90 percent, protecting water from sediment, the number one pollutant of US waterways.


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