Pesticide atrazine is an endocrine disruptor

Posted on Apr 18, 2009 by Susie Collins in Blog, Environment, Research, Susie Collins

“From Silent Spring to Silent Night,” a talk by biologist Tyrone Hayes on his seminal research on the pesticide atrazine.

Fascinating talk by Tyrone Hayes, professor of integrative biology at the University of California, Berkeley, given in 2007 at Humphrey Institute in Minneapolis. He is an authority on the effects of the pesticide atrazine on frogs and other forms of life. Not surprisingly, he’s not very popular with chemical companies for his views and proven research. The conclusion Prof. Hayes reached after conducting his seminal research: BAN ATRAZINE.

This talk is particularly disturbing to me because we have Atrazine in our water, a gift from the former sugar industry here on the Big Island of Hawaii. It’s under federal limits, but as Prof. Hayes points out, in the case of atrazine, exposure to minute amounts is what causes reproductive harm and rise in cancer rates.

Endocrinology is the study of hormones. Hormones (endocrine substances) control growth, reproduction, metabolism, development, behavior, immune function, and stress, among other functions critical for life. Hormones are also important in many disease states including diabetes and cancer. Endocrine disruptors, such as atrazine, which interfere with hormone production and/or activity, can affect any of these processes.

In particular, atrazine inhibits production of testosterone (the male sex hormone) and induces estrogen production (the female sex hormone), upsetting the balance between these two hormones. This effect of atrazine has been observed and published in fish [1, 2], amphibians [3, 4], reptiles [5, 6], and mammals [7-14]. The result is chemical castration (demasculinization) and feminization. In fish [1, 2], amphibians [3, 4, 15-20], and laboratory rodents [7, 8, 10], the decrease in testosterone results in decreased sperm counts, impaired fertility, and a reduction in masculine features. Similarly, atrazine exposure is associated with decreased sperm and reduced fertility in humans [21]. The increase in estrogen by atrazine results in feminization of males in fish, amphibians, and reptiles. “Feminized” male fish [2] and amphibians produce eggs and egg yolk [16, 18] and some males even grow ovaries (become hermaphrodites) [3, 4, 17].

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…atrazine exposure in rodents impairs immune function [32-40] and decreases an exposed animal’s ability to fight cancer [33] and other diseases. Further, atrazine exposure in rodents can lead to hypersensitivity [36], making exposed animals more susceptible to allergies.