Atrazine, a triazine herbicide, stops pre- and post-emergent weeds by inhibiting electron transport, ultimately blocking photosynthesis. [More about the quantum mechanical properties of photosynthesis will be noted in a subsequent blog.] EPA reexamined data on the herbicide's putative toxicity four years ago as part of a systematic review of the safety of older pesticides, those initially registered for use before 1984. Atrazine was reregistered, which meant that it could continue to be sold. As part of this review, EPA concluded that Atrazine's regulated use could continue without posing undue risks to health and the environment. Yet, the pesticide is banned by the European Union and, ironically, in Switzerland, where Atrazine's leading manufacturer, Syngenta, is headquartered. I have known a number of amateur vintners that have been using Atrazine in their vineyards for at least the last 3 decades.
In recent years, however, questions have surfaced about Atrazine's safety, especially after monitoring programs picked up the chemical in drinking water and lab studies demonstrated the pollutant's ability to feminize and even deform amphibians and fish. Last fall, EPA announced it was reopening an inquiry into allegations of Atrazine's risks. EPA instructed its Scientific Advisory Panel on pesticides to reevaluate the weed killer's safety through three meetings this year, the first of which took place in February 2010. The panel will review human data and any studies, including animal or test-tube assays, that might suggest risks to people. See http://www.epa.gov/opp00001/reregistration/atrazine/.
Among the criticisms was a report in August 2009 by the Natural Resources Defense Council: "Poisoning the Well: How the EPA is ignoring atrazine contamination in surface and drinking water in the central United States." The NRDC analysis of data that the EPA had collected, but had not publicly released, showed that traces of atrazine frequently polluted not only rivers but also water exiting the tap, oftentimes at concentrations exceeding EPA's 3-parts-per-billion limit for drinking water. See http://www.nrdc.org/health/atrazine/default.asp.
For its part, Syngenta Crop Protection, based in Greensboro, N.C., the largest U.S. producer of atrazine, has argued that EPA's new review is unnecessary because it has been subjected to seven Scientific Advisory Panels, 15 years of special review, and the reregistration process in 2006.
While the comments of Syngenta have some merit, there would appear to be considerable new data that have not, for some bizarre reason, previously been part of any systematic federal review. One of the areas that appears to be under-explored is the impact of Atrazine on hormone disruption, including in humans.
As they say, stay tuned.