Pesticides in Combination Shown to Increase Endangered Salmon Threat
Thursday, March 5th, 2009(Beyond Pesticides, March 5, 2009) A new study published in the March 2009 issue of Environmental Health Perspectives finds that pesticide combinations cause more harm to endangered salmon than ndividual pesticide exposure. This means that single-pesticide risk assessments required by the Environmental Protection Agency (EPA) inadequately assess hazards. Mixtures of organophosphate and carbamate pesticides are commonly detected in freshwater habitats that support threatened and endangered species of Pacific salmon. According to the researchers from the National Oceanic and Atmospheric Administration (NOAA) Fisheries and Washington State University, these pesticides inhibit the activity of acetylcholinesterase (AChE) and thus have potential to interfere with behaviors that may be essential for salmon survival. The researchers measured brain AChE inhibition in juvenile coho salmon exposed to sublethal concentrations of the organophosphates diazinon, malathion, and chlorpyrifos, as well as the carbamates carbaryl and carbofuran. The pesticides were tested individually and in combination. They plotted AChE levels on a curve to determine whether the toxicologic responses to binary mixtures were additive, antagonistic (lesser than additive) effect, or synergistic (greater than additive). The authors observed addition and synergism, with a greater degree of synergism at higher exposure concentrations. Several combinations of organophosphates were lethal at concentrations that were […]
