Common herbicide used on U.S. crops castrates male frogs

Thursday, May 27, 2010 by: Ethan A. Huff, staff writer
Tags: herbicides, frogs, health news

(NaturalNews) The dangers associated with pesticide and herbicide use have been receiving increased attention in the media these days. Everything from their contamination of local water supplies to their residue on food has been making headlines. But a new study has found that one popular weed killer is actually causing a certain species of frog to turn from male to female.

Atrazine, a popular weed killer used in crop fields, has recently been implicated in a similar study to cause human birth defects. Scientists have found that atrazine and other agricultural chemicals are likely responsible for the significant rise of birth defects throughout the last several decades. But a recent report from the University of California-Berkeley (UC-B), indicts atrazine even further.

Biologists from UC-B found that long-term exposure to low levels of atrazine essentially castrated about 75 percent of the male frogs on which it was tested. Frogs were exposed to the toxic herbicide at levels of 2.5 parts per billion (ppb) in water, a level that is 16 percent lower than what the U.S. Environmental Protection Agency (EPA) considers safe for drinking water. One out of every ten frogs also ended up turning into a female frog.

Like other pesticides and environmental toxins, atrazine interferes with hormones. It is an endocrine disruptor that seems to replace testosterone, the primary male hormone, with estrogen, the primary female hormone. The result is a severe alteration of normal male function that can actually turn a male into a female.

"The effects of atrazine in the long term have been shown to demasculinize or chemically castrate, combined with complete feminization of some animals," explained Tyrone Hayes, a biologist and herpetologist from UC-B that led the study.

The amazing thing about the frogs who experienced the sex change was that they actually began producing viable eggs. The male frogs who turned female were able to copulate with naturally male frogs and produce eggs. The other 90 percent of male frogs exposed to atrazine experienced decreased sperm count, lowered libidos and diminished fertility.

In typical fashion, some atrazine producers were quick to decry the findings.

"We haven't seen these kinds of responses that Dr. Hayes reports. Some of these studies are poorly conducted and are entirely inconsistent," explained Keith Solomon, an environmental toxicologist at the University of Guelph in Ontario, Canada. Solomon also served as a consultant to Syngenta.

Syngenta's principal scientist, Tim Pastoor, explained in a CNN interview that atrazine levels within the EPA's guidelines are safe, and that political pressure is responsible for efforts to get atrazine re-evaluated. Syngenta's website also purports that atrazine residue on crops and in water are not a health risk.

Yet of all the available studies on atrazine, only its manufacturers' studies found that the pesticide is safe. All other independent studies and reviews have found significant dangers associated with it. It has been continually shown to lead to cancer, birth defects, and severe endocrine disruption.

In 2004, the European Union (EU) banned atrazine because it was finding levels of the chemical in its water supplies that consistently exceeded the 0.1 ppb established threshold. Yet in the U.S., atrazine continues to be used, and is considered to be acceptable at much higher levels.

Atrazine is most commonly used on corn crops, but is also used on sorghum and sugar cane. Many farmers love it because it eliminates the need to have to till the soil. In 2008, it was estimated that over 60 million pounds of atrazine were used on crops.

A 2006 study by the U.S. Geological Survey found atrazine in nearly three-quarters of stream water and in roughly 40 percent of all groundwater supplies. This was based on data collected between 1992 and 2001. It is difficult to say what kinds of levels would be found on samples taken today.

The Natural Resources Defense Council (NRDC), an advocacy group that works to protect the health of the environment, issued a report in 2009 indicating that water supplies near agriculture fields that use atrazine are the most contaminated. Particularly in some midwestern and southern states that have high agricultural land usage, atrazine levels can be particularly high.

Individuals can remove atrazine from their home water with carbon filters, and some municipal water systems use the technology as well. It is important to investigate and take proper measures to ensure that atrazine does not enter your home through your water.

Ideally, dangerous pesticides like atrazine will eventually be banned and eliminated from agricultural use. As people become more aware of the severe negative effects of such poisons on their health and well-being, not to mention on the environment, it can only be hoped that increased pressure to stop their use will ensue. And though it cannot be said for sure, atrazine likely has a similar effect on humans as it does on frogs, and should not be considered safe at any level.

Sources for this story include:

http://edition.cnn.com/2010/TECH/science/03/...

http://www.water-research.net/atrazine.htm