Tyrone B. Hayes (born July 29, 1967 in Columbia, South Carolina[1]) is a biologist at University of California, Berkeley.[2] He is perhaps best known for his work on the effects of atrazine on frogs, causing demasculinization in Northern Leopard Frogs.[2]
In 2002, Nature published research by Hayes and colleagues showing that "developing male frogs exhibited female characteristics after exposure to atrazine ... at exposure levels deemed safe by the US Environmental Protection Agency (EPA).",.[3] More recently, Hayes has been a co-author on work that details atrazine inducing mammary and prostate cancer in laboratory rodents and highlights atrazine as a potential cause of reproductive cancers in humans.[4]
According to Hayes, "the induction of aromatase and estrogen production has been demonstrated ... in fish, frogs, alligators, birds, turtles, rats and human cells.",[5] and further, "I believe that the preponderance of the evidence shows atrazine to be a risk to wildlife and humans. I would not want to be exposed to it, nor do I think it should be released into the environment."[5] Syngenta has fought this research by quoting EPA findings regarding methodological problems in his research, which Hayes refutes. In 2007, the EPA's review of science literature concluded against claims made by Hayes and concluded its evaluation by stating: "At this time, EPA believes that no additional testing is warranted to address this issue."[6]
Currently, the research that Hayes has published are being used as evidence in a class action lawsuit against Syngenta by 15 water providers in Illinois seeking $350 million to clean drinking water of atrazine. A similar case involving six states is also occurring in federal court.[3]