The substance is known as atrazine, and researchers from Miami University found in tests they conducted on cricket frogs that it resulted in a 55 percent reduction in the number of male frogs compared to female frogs. In other words, atrazine appears to be a potent estrogen-mimicking herbicide that is particularly harmful to the male species.
The second most commonly used herbicide in the United States, atrazine has long been the subject of controversy. Earlier research has similarly confirmed its gender-bending properties, warning that human exposure likely has a similar effect. The Pesticide Action Network (PAN) agrees, indicating that this endocrine-disrupting chemical (EDC) can cause damage to the hormone systems resulting in delayed puberty and "chemical castration" in males.
Further, atrazine has been shown to damage the reproductive system, increasing the risk of infertility, low birth weight, miscarriage, and birth defects. Atrazine is also highly carcinogenic – so much so that the President's Cancer Panel Report lists it alongside dichloromethane and other known cancer-causing substances. The U.S. Environmental Protection Agency (EPA) is currently conducting a review of atrazine to determine the extent of its carcinogenic potential.
One of the major reasons why atrazine is such a threat is its persistent nature. After being sprayed on crop fields, it ends up running off into streams, rivers, and lakes, some of which are used to provide drinking water to local municipalities. The result is that people end up drinking and bathing in this contaminated water, which increases their risk of suffering hormone problems.
An analysis of state and federal records conducted by the Chicago Tribune found that more than one million people living in 60 communities throughout Illinois, a major agricultural state, are exposed to atrazine in their drinking water on a regular basis.
This, of course, represents only the levels of atrazine that are detected on the four occasions per year when water utilities are required by the EPA to test for it. Short-term "spikes" of atrazine, in other words, go largely undetected – spikes that typically occur during the intense spraying season.
As it turns out, the EPA has a cozy little relationship with Syngenta, the leading manufacturer of atrazine in the U.S. What would otherwise mean weekly and even bi-weekly testing mandates has essentially been reduced to quarterly requirements by the EPA, allowing Syngenta to continually poison water supplies without consequence.
However, even with such limited testing, the data shows that atrazine is typically present at levels higher than the 3 parts per billion (ppb) threshold established by the EPA for safety. More than half of the communities in the Midwest that undergo such testing have shown atrazine levels higher than the federally imposed limit. In one instance in the city of Flora, Illinois, atrazine was detected at levels as high as 30 ppb.
Recognizing the widespread problem of atrazine and how little is known about how it affects humans and other mammals in the long term, the Miami University researchers who worked on the study involving frogs see a dire need for more research into how the chemical affects people. They stated that there is a need to "translate these impacts to their population-level, ecological, and evolutionary consequences in ways that can ultimately generate predictions for risks faced by untested species."