One of the environmental downsides of pesticides is that all that runoff has to go somewhere and much of it ends up in rivers and streams, causing water contamination.
Until now, researchers didn’t know the extent of water contamination worldwide. But new research shows that agricultural application of pesticides contaminates rivers and streams on 40 percent of the land surface, according to the Environment News Service. Specifically, stream pollution and water contamination is prevalent in the U.S., the Mediterranean, Central America, and Southeast Asia, according to researchers at University of Koblenz-Landau,University of Milan, Aarhus University, and Aachen University.
“Our analysis provides a global map of hotspots for insecticide contamination that are a major risk for biodiversity in water bodies. To our knowledge this is the first study that assesses insecticide contamination of water bodies on a global scale,” Professor Dr. Matthias Liess from the Helmholtz Center, who serves on the scientific advisory board for Germany’s National Action Plan on Sustainable Use of Plant Protection Products said to the Environment News Service.
In all, 4 million tons of agricultural pesticides are applied annually around the world and that number is on the rise as third world nations continue to adopt first world pesticide use.
“The risks of insecticide exposure to water bodies increased significantly the further South one travelled on a North-South gradient in Europe, North America and Asia, mainly driven by a higher insecticide application rate as a result of higher average temperatures,” Dr. Mira Kattwinkel, a researcher at the Swiss Federal Institute of Aquatic Science and Technology told the Environment News Service.
Contaminated water systems have a huge impact on local water systems by killing a range of species including invertebrates, insects, crustaceans, snails, and worms. Not to mention that contaminated water and soil leads to issues with local water supplies, although, pesticides are less common in ground water than they are in streams.
In the U.S., the Mississippi River basin is among the most intensely farmed areas in the nation. In fact, it’s estimated that as much as two-thirds of all pesticides used in agriculture are used in this area. Storm runoff concentrates these pesticides in rivers and streams. According to the U.S. Geological Survey, “[t]he half-life of pesticides, once they are in surface water, is generally much longer than in soil because water contains much less organic matter and fewer micro-organisms to degrade the pesticides.”
Beyond Pesticides reports that we’re already seeing some of the side effects of this contamination including frogs exhibiting hermaphrodism when exposed to atrazine, even in below the legal allowable limits. Low birth weights and increased instances of breast cancer are tied to herbicide-contaminated water. Plus there’s the stress that degraded stream water puts on municipal water systems. Surface water, which was the subject of the study above, is the most vulnerable to contamination and it supplies 47 percent of water in the U.S.
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Image of man spraying pesticides from Shuttershock