Spring Means Weedkiller In Our Water

So you eat organic, avoid using bug sprays around the house, and keep the yard looking good with elbow grease rather than chemicals.  That’s great!  Does that mean you are safe from pesticides?  Unfortunately, maybe not.  You could very well be swimming in it or drinking it.

Atrazine is a popular weed-killer that is used on mainly corn, sugar cane, lawns, and golf courses.  Last fall, our report Poisoning the Well found that atrazine was detected in most watersheds and drinking water systems that were monitored across the Midwest and the South

We have now updated our report with Still Poisoning the Well with more recent monitoring data and more recent scientific findings about the harms associated with atrazine exposure.  My colleague, Jen Sass, has done a great job of keeping track of all the dangers with atrazine, and our update adds to that growing list

Whenever there are heavy rains after atrazine is applied to a field or lawn, much of it is washed into nearby rivers and streams.  So it doesn’t come as much surprise that all the watersheds that were monitored found atrazine contamination.  What was surprising was that atrazine was showing up in drinking water coming out of the tap – sometimes at alarmingly high levels.

EPA regulates how much atrazine can be in our drinking water (no more than 3 parts per billion), but compliance with the standard is based on the average of 4 samples taken over the course of a year.  The data in our report were from samples taken much more frequently (up to once a week during the growing seasons in the spring and summer) – sometimes up to 30 times a years. 

And what did we find?  High spikes of atrazine in drinking water!  Turns out that when you sample the water more frequently, you can catch spikes of atrazine that last a few weeks, while sampling only once every 3 months (as required by the EPA rules) means it’s easy to miss these spikes. In fact, of the 153 water systems that were sampled between 2005 and 2008, 100 drinking water systems had spikes of atrazine in their untreated water that exceeded 3 ppb.  Two-thirds of these 100 systems had spikes of atrazine greater than 3 ppb in the treated water.  Most troubling, six water systems had high enough atrazine levels to exceed the EPA drinking water standard of 3 ppb. 

And here’s a little secret that Syngenta (the manufacturer of atrazine) doesn’t want people to know: we don’t actually need atrazine.  Studies have shown that not using atrazine might only cause a loss of corn yields as little at 1.19%.  And on the flip side, water systems are spending tens of thousands of dollars treating water to remove contaminants like atrazine. 

So check out our report and see if your system is keeping atrazine out of your water.  If it doesn’t, contact them and ask them why not. 

About the Authors

Mae Wu

Senior Attorney, Health program

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