Testes Hit by Herbicides

Male gonads of many species suffer negative effects from exposure to the herbicide atrazine.


A pesticide is shown to cripple the male gonads of more than 100 species.

Certain frogs appear to suffer the most dire effects as the chemical made males turn into females.

A review of 142 studies on the effects of the herbicide atrazine had bad news for testes.

"Essentially, atrazine chemically castrates animals. When you look at a male exposed to atrazine, the testes are missing sperm," Tyrone Hayes of the University of California, Berkeley told Discovery News.

The effects of atrazine on male development are consistent across all examined animals, found a study published by a team of 22 researchers from more than 60 nations in the Journal of Steroid Biochemistry and Molecular Biology.

Mammals, reptiles, and fish were all affected, but amphibians caught the worst of it. In a study by Hayes, male African clawed frogs turned into females after exposure to atrazine, which kills weeds around the world in everything from corn fields to orchards.

"And this is not at extremely high concentrations" said co-author of the review Val Beasley of the University of Illinois in a press release. "These are at concentrations that are found in the environment."

Humans aren't spared the effects of atrazine, the world's second most common herbicide after glyphosate, Hayes said.

Hayes pointed to studies correlating atrazine exposure to low sperm quality, birth defects, miscarriage, and breast cancer

"The hotspot is probably the US, because we use so much" Hayes said. "The biggest hotspot in the US is the Midwest, the cornbelt, another is Florida where it is used on sugar cane."

But, he added, "We're all exposed to it. Surface water, rainwater you name it atrazine is in it."

The European Union has already banned the use of atrazine

"I think a global ban is certainly in order" Hayes said.

The maker of atrazine, Switzerland-based Syngenta, disagrees

"The science is clear. Atrazine cannot, does not, and will not cause adverse effects at levels to which people would ever be exposed in the real world" Ann Bryan, Syngenta's senior manager of external communications told Discovery News.

"Independent organizations such as the EPA, World Health Organization , Australian Pesticides and Veterinary Medicines Authority , and others have conducted or reviewed studies that consistently support the safety of atrazine" Bryan said.

Syngenta and Hayes haven't always been at odds.

Hayes was introduced to atrazine when he worked on the chemical for Syngenta, he said. Now, though, Hayes says his public talks have been disrupted by Syngenta, and he's received vulgar and threatening comments from them.

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"There is no truth to these claims" said Syngenta's Bryan.

No matter what side of the atrazine debate wins, there will be economic consequences.

In the face of a global atrazine ban... "We would be concerned for the millions of farmers and the US consumers who benefit from atrazine. US consumers benefit by $3.6 to $4.4 billion annually due to decreased producer costs" Bryan said.

Banning the chemical in just some areas might not be a good idea

"There needs to be a system of global [agricultural chemical] regulation" review co-author Val Beasley told Discovery News.

"What we don't want to see is a situation like DDT" said Beasley.

After being banned in the US, DDT continued to be used in the developing world to eliminate insects.

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