NORTH America鈥檚 Great Lakes, which contain one-fifth of the world鈥檚 freshwater, are uniformly polluted with the herbicide atrazine. In a two-year study, Shawn Schottler and Steven Eisenreich of the University of Minnesota at Navarre found atrazine in all 490 samples of lake water they collected. The herbicide is used extensively in the crop growing regions around the lakes.
Concentrations of atrazine ranged from 35 to 110 nanograms per litre, suggesting a probable total of around 600 tonnes in the lakes as a whole, say Schottler and Eisenreich in the current issue of Environmental Science & Technology.
鈥淎s far as we know, the levels found do not suggest that there are acute ecotoxicological effects,鈥� says Eisenreich. However, he warns that the herbicide remains in the water for decades, and could accumulate to levels that harm fish and other aquatic organisms.
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