Atrazine and Amphibians

 

            Atrazine – or 2-chloro-4-6-s-triazine – is one of the most widely used herbicides in the continental United States (1). Since its introduction in 1959 (2), farmers have been applying atrazine to prevent the growth of weedy grasses and broadleaved plants. Currently over 27 000 tonnes is applied annually to corn, sorghum and sugar cane (1). And that is fine, because it only kills weeds… right?

Well, in 2002, Dr. Tyrone Hayes of UC Berkeley published a study investigating atrazine’s effects upon amphibian development. Both in the lab as well as at atrazine-contaminated sites throughout the US, he found that frogs exposed to atrazine developed abnormal gonads (3). In many cases, both male and female reproductive organs were present on the same frog!

 His findings lead to widespread public outcry and concern, as well as calls for more studies to be conducted. Over the past ten years, Dr. Hayes has published ten more studies all with similar findings: that atrazine disrupts the endocrine system of amphibians, reptiles and fish and can result in males developing female reproductive parts (4).

On the other hand, Syngenta – the company that sells atrazine in the United States – conducted several studies of their own, and in every one concluded that atrazine had no effect upon amphibian development (5).

So… who is correct? Does atrazine affect frogs as Dr. Hayes found, or is Syngenta right in that atrazine is harmless?

However in

I think this is a quandary worthy of discussion: Should a company study the health and environmental impacts of their own products, at the risk of their findings negatively affecting their own profit margin? Or if you trust the findings of Syngenta, how did Dr. Hayes’ find what he did in the first place?

How do we know which studies to believe?

As scientists, what we believe should be irrelevant to our decision making; it should be what we think. But what are we to think about this issue when the ‘truth’ is so unclear?

I suppose the next question we should ask is, do we care about the effect of atrazine upon amphibian species, or do we spend our time and money upon a less controversial issue? On one hand, the prevalence of use of this herbicide means any impact it has would be massive and widespread. But on the other hand, if it were not used, food would likely cost a fair bit more (6).

So what do we choose – the science of Syngenta or the findings of Dr. Hayes? Do we try to save the amphibians or continue to have cheap food with a side helping of atrazine?

On a side note, the EU has not allowed the use of atrazine in their food system.

1.    U.S. Environmental Protection Agency. 2013. Atrazine Updates. Available from http://www.epa.gov/opp00001/reregistration/atrazine/atrazine_update.htm
2.      AGsense. 2013. Atrazine Regulatory Issues. Available from http://agsense.org/atrazine-regulatory-issues
3.      Nature. 2002. Feminization of male frogs in the wild. Available from http://www.nature.com/news/2002/021031/full/news021028-7.html
4.      Web of Knowledge. 2013. Web of Science. Available from http://apps.webofknowledge.com.ezproxy.tru.ca/summary.do?SID=2C3kGDLp35gO7E8k535&product=WOS&qid=2&search_mode=GeneralSearch
5.      AGsense. 2013. Atrazine and Frogs. Available from http://agsense.org/atrazine-regulatory-issues/atrazine-and-frogs/
6. Ackerman F. 2007. The Economics of Atrazine. Int J Occup Environ Health. 13:441-449.