USA Refuses to Ban Atrazine

by: Posted on: August 08, 2013

Editor’s Note: Atrazine is used in many herbicides in the USA. It is a known endocrine disruptor that reduces testosterone production and stimulates estrogen secretion. Why is a conflict of interest within the EPA stopping us from banning it?

By Alex Valentine, Read the Dirt intern

Summer is in the air, a time when the sidewalk is decorated with pink petals and the deep croak of the frogs punctuates the night. This croaking marks more than just an annual serenade or an ode to summer nights but also signals the nearing birth of a generation of frogs and amphibians alike.

However, this captivating time of year is also a time to be aware of the threats that these creatures face and the dwindling amphibian populations around the globe. One of the most controversial and pervasive culprits in this discussion is the herbicide atrazine.

According to the Environmental Protection Agency (EPA), atrazine is applied on agricultural land both “before and after planting to control broadleaf and grassy weeds.” Atrazine is used extensively in the U.S., particularly in corn, sorghum and sugarcane production. Atrazine is one of the most commonly used herbicides in the world with roughly 80 million pounds being applied annually in the U.S. in addition to use in over 50 countries.

With such widespread use comes the inevitable contamination of countless water supplies through runoff of the herbicide. This ultimately led to the ban of atrazine in the European Union in 2004. Atrazine has also been linked with possible carcinogenic effects, and endocrine disruption—altering of hormone systems—in amphibians and humans. All of these factors have contributed to a long history of controversy regarding atrazine and has caused many researchers and environmental organizations to call for a ban on atrazine in the U.S.

Of the most cited and concerning studies on the effects of atrazine was the one conducted by Dr. Tyrone Hayes, a scientist from UC Berkeley in 2002. Dr. Hayes and his colleagues found evidence that exposure to atrazine resulted in demasculization and hermaphroditism of male frogs even at very low concentrations (30 times lower than EPA recommended levels in drinking water). In fact, at all doses above .01 parts per billion all ‘specimens’ experienced gonadal abnormalities that were never observed in control animals. These abnormalities included reduced larynges and plasma testosterone in males and excess estrogen in females. After much replication, Hayes’ laboratory concluded that atrazine consistently inhibited testosterone production and generated estrogen secretion.

Dr. Hayes’ discoveries have ultimately transformed him into one of the most passionate advocates for the banning of atrazine, because of its dangers as an endocrine disruptor. Hayes emphasizes that while his work at UC Berkeley was performed using the African clawed frog (Xenopus laevis), various field studies suggest that wild frog populations likely suffer similar effects all over the world.

Even more troubling is the fact that atrazine is most often applied during the breeding season for amphibians with the highest levels of atrazine runoff occurring during spring rainfall. This means that the timing of atrazine application and key developmental stages for frog and other amphibian larvae overlap.

Despite the concern over atrazine’s capacity to disturb hormonal and reproductive systems in amphibians and humans, the EPA has yet to outlaw the use of atrazine. Member of congress, Rep. Keith Ellison (D-Minn) has twice proposed legislation in attempts to ban the sale and use of any pesticide containing atrazine. Thus far, both attempts have been unsuccessful.

The EPA and its Scientific Advisory Panel (SAP) have reviewed the studies done on atrazine and its effects, including the work of Hayes’ lab. They have stated that there is not yet enough evidence to determine if atrazine poses a threat to amphibians. In a cumulative risk assessment released by the U.S. EPA in 2006, the EPA declared that atrazine was not a cause for concern and posed no danger to “consumers”.

Dr. Hayes has resigned from his former post as a member of the SAP panel and continues his work on atrazine and its impacts. Hayes has also stated that those studies and conclusions that deny atrazine related risks often lack credibility or are funded by Syngenta, the manufacturer of the herbicide. Not surprisingly, Syngenta has countered this by releasing several statements in direct opposition to Hayes and other studies that suggest reproductive and development hazards related to atrazine consumption.

As it currently stands, atrazine will undergo registration review by the EPA as a re-evaluative measure in mid 2013. During this review the EPA will examine atrazine and other existing pesticides, ultimately forming a work plan that will be available for public comment for a 60-day period. This plan will include both what is known about atrazine and what data is still lacking.

Whatever the outcome of this review brings, the information that is already available on atrazine and that continues to emerge from labs like Dr. Hayes’ provides compelling evidence regarding the effects of pesticides on amphibians. While atrazine continues to make its way through the political process and across America’s cornfields, it is important to remember that many of the species that will live and breathe these chemicals may also suffer from the most internal and detrimental effects. Perhaps, then all of us could benefit from listening and appreciating the songs of summer just a little more.


Photo: Kathryn Kozowski

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