Tyrone Hayes: I’ve gone from being a little kid who really just loves the outdoors, really just loves the wildlife, to being a professional scientist, and a teacher, to then using those skills to become an advocate to get involved in public policy.

That’s Tyrone Hayes, biologist at the University of California – Berkeley. Over years of examining the impacts of pesticides on amphibian and human health, Hayes has become an advocate of banning the pesticide Atrazine now widely used in the U.S. He told EarthSky he thinks it’s time for scientists to begin speaking out.

Tyrone Hayes: There are people who feel that a scientist has to be objective, and you can’t get involved in the politics, and public presentations and things. And I feel very differently. I think the people who have an understanding of the science and know the science are very much the people who should be presenting to public, and helping lawmakers understand what the real implications are.

Hayes’ research indicates exposure to Atrazine causes abnormalities in frogs and has been linked to cancer in humans.

Tyrone Hayes: Economics, and in some cases, the need to grow more food for a growing population, causes us to turn a blind eye – while at the same time, we’re really putting the environment at risk.

In April of 2002, Hayes’ team at the University of California, Berkeley announced that Atrazine – a common herbicide used to control weeds in crop fields – can have a devastating effect on frogs exposed to just one thirtieth the concentrations allowed by the U.S. Environmental Protection Agency (EPA).

The chemical can turn tadpoles into hermaphrodites – animals that have both male and female sexual characteristics. According to the U.C. Berkeley press release, “The herbicide also lowers levels of the male hormone testosterone in sexually mature male frogs by a factor of 10, to levels lower than those in normal female frogs.” The research appears in the April 16, 2002 issue of Proceedings of the National Academy of Sciences.

So-called “estrogen mimics” like Atrazine are found in many compounds that have become common in modern life – pharmaceuticals, pesticides and industrial or residential waste. Some enter the water in effluent from wastewater treatment plants. In some animals such as fish, frogs and birds – and at certain levels – these chemicals can cause males to become more like females, sperm counts to shrink, or eggs to become thinner.

Some scientists also worry about possible effects on humans.

Our thanks to:
Tyrone Hayes
Department of Integrative Biology
University of California
Berkeley, CA