EPA Reevaluates Popular Weed Killer

The EPA has announced it will review the health effects of a popular weed killer used mainly by the agricultural industry. From the KUHF News Lab, Wendy Siegle has the story.


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Local environmentalist Charlotte Wells and her team of volunteers use a hands-on approach to control invasive plants and weeds around Galveston Bay.

“So we take our different tools and implements and cut it back instead of using pesticides.”

Wells is part of a global organization that aims to protect water resources around the world. Of course, her approach can prove to be quite laborious, which is why the majority of the agricultural industry use atrazine, the country’s most popular herbicide. But the use of atrazine has been controversial among some environmentalists and scientists.

“The problem with herbicides and pesticides is when it rains, that rain water flushes the pesticide into our drinking water or our bays where we’re eating from them, or drinking from them.”

Past studies have linked atrazine to low sperm count, birth defects, low birth weight and hormonal disruption. In the most recent study, the Natural Resource Defense Council found atrazine in 90-percent of the drinking water that was sampled.

The NRDC also cited gross inadequacy in the EPA’s standard for monitoring and regulating the herbicide, because it fails to measure high use periods when atrazine concentrations in drinking water spike. NRDC program attorney Mae Wu says assessing the levels of atrazine by the annual average can be misleading.

“The problem is that when it comes to regulating atrazine, they look at it on an annual average.  So the winter data and the fall data when atrazine isn’t being used is being averaged with the spring and summer data.”

In light of the NRDC’s latest study, the EPA has just announced this week that it will be conducting a year long review of atrazine to determine its effects on humans. The agency will also reevaluate the methods used to detect the herbicide in drinking water. I spoke with Steven Bradbury, the deputy director at the EPA.

“We’ll be getting feedback on the scientific foundation for our regulatory position for atrazine. And again, we don’t want to prejudge what these independent scientists will tell us, but clearly there is a whole range of possibilities.”

The NRDC hopes atrazine will be banned altogether, a position the European Union took years ago. Thankfully for Houston residents, the biggest concern is around agricultural areas, where atrazine use and run-off is high. According to 2008 data, atrazine levels in Houston’s drinking water were significantly below the EPA’s current annual average standard. And KUHF has confirmed that to ensure superior water quality, the Houston water system tests for atrazine more than twice the obligatory 4 times a year.

But Wu warns against complacency as studies show that atrazine poses health risks at much lower concentrations than previously thought. And she stresses that when it comes to fetuses, it’s the timing of the exposure to atrazine that is really critical, not just the dose.

“So even though they may not be high levels, super high levels of atrazine, even having a smaller amount that a fetus is exposed to, if it’s during that critical window of development than that’s when you’ll see the problems.”

Back with Charlotte Wells, she hopes the outcome of the EPA’s review will lead to a new way of approaching the use of all pesticides.

“I would like us to look at the precautionary principle which is to look at what harm a product such as atrazine might do before we put it on the marketplace.”

From the KUHF News Lab, I’m Wendy Siegle