Scientists and Industry Square Off Over the Potentially Harmful Effects of Atrazine

As a scientist, it doesn’t matter how many papers you’ve published or how much potential you’ve got; butting heads with one of the largest agribusinesses in the world is a dangerous proposition. Rachel Aviv published a piece in the February 10th edition of the New Yorker detailing the story of Tyrone Hayes, a biologist who discovered harmful effects of the herbicide atrazine, and the elaborate smear campaign its manufacturer Syngenta ran against him.

Although its use is currently restricted by the E.P.A., atrazine is still approved for a number of applications and is the second most used pesticide in America1. As well, the E.P.A. itself has noted that atrazine can persist in soil for up to 4 years. This is particularly troubling for pregnant women because a number of recent studies have demonstrated that atrazine is associated with striking developmental defects in newborns as well as premature births and low birth weights in full term babies2. At this point you might be wondering how atrazine could possibly still be in use. You would not be alone in this.

Aviv reports that 15 years ago when Tyrone Hayes, at the time collaborating with Syngenta, initially observed troubling effects of atrazine on the reproductive development of frogs the company sought to bury the findings. Ultimately this forced Dr. Hayes to break ties with them and publish independently, which he did in a 2002 paper3. Sadly, but perhaps not surprisingly, rather than expressing concern that their product might be harmful Syngenta responded by attempting to discredit Dr. Hayes and his work.

This same pattern appears to have recurred many times over the next decade, with Syngenta increasingly ramping up both their attacks on Dr. Hayes and their defense of atrazine. Recently unsealed documents show Syngenta resorting to tactics like hiring scientists to argue against Dr. Hayes and his colleagues, attempting to exploit Dr. Hayes’ difficult childhood and trying to entrap him legally. There is also now good reason to question the validity of much of the science Syngenta has produced defending atrazine. Indeed Aviv cites a paper claiming “the single best predictor of whether or not the herbicide atrazine had a significant effect in a study was the funding source”4.

The European Commission removed atrazine from the market in 2003. The E.P.A. on the other hand continues to maintain that there is insufficient evidence that atrazine poses a risk to humans or the environment. This is because in the United States there is an almost insurmountable burden of proof placed on regulators. In fact, as Aviv writes, only five industrial chemicals have been banned by the E.P.A since the mid-seventies while eighty thousand were approved for us. As opposed to the cautionary approach to regulation used by the European Commission, the E.P.A. refuses to act if there is any scientific ambiguity leaving the door open for industry to indefinitely delay action. As such atrazine and other potentially harmful products are presumed innocent until proven guilty while researchers like Dr. Hayes face the ruination of their reputations and careers for publishing their findings. (New Yorker)


[1] This estimate is according to a 2007 E.P.A. assessment. While the E.P.A. hasn’t published a more up to date list other groups suggest that atrazine remains second in usage

[2] All studies were published in peer reviewed scientific journals.

[3] Hayes TB, et al. Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses. Proc Natl Acad Sci U S A. 2002

[4] Rohr and McCoy. Preserving environmental health and scientific credibility: a practical guide to reducing conflicts of interest. Policy perspectives. 2010