Garden-variety pesticides add up to more than the sum of their parts when it comes to attacking the nervous systems of salmon, a newly published study finds.
Scientists at WSU and the National Oceanic and Atmospheric Administration Fisheries Service analyzed combinations of various pesticides to learn how they would affect juvenile salmon. Previous studies have tested pesticides individually to establish levels lethal to fish.
“We need to design new research that takes into effect the real-world situation where pesticides almost always coincide with other pesticides,” co-author Nathaniel Scholz, a research zoologist at the NOAA Fisheries Service Northwest Fisheries Science Center, told the Associated Press.
WSU entomologist and ecotoxicologist John Stark co-authored the study and the research was done in his lab at the WSU Puyallup Research and Extension Center. Stark is now the center’s director. Vince Herbert with the WSU Tri-cities Food and Environmental Quality Laboratory is also a co-author of the study.
“The findings are significant and I hope they will encourage government regulators, specifically the Environmental Protection Agency, to rethink their approach to risk management in protecting salmon,” Stark said.
The results of the research were published Monday in the March issue of Environmental Health Perspectives. The study examined five common pesticides: diazinon, malathion, chlorpyrifos, carbaryl and carbofuran, all of which suppress an enzyme necessary for nerves to function properly.
Although the idea that pesticides act synergistically is not new, Inge Werner, director of the aquatic toxicology laboratory at the University of California at Davis, told the AP the new findings were definitive, even at levels that don’t kill fish outright. Werner was not involved in the study.
“We may not see the big fish kills out there anymore like we used to,” Werner told the AP. “But the subtle, sub-lethal effects that basically render fish unfit for survival in the wild are much more important. In certain areas, pesticides really are a very important factor” in salmon survival.
Jeffrey Jenkins, a professor of environmental and molecular toxicology at Oregon State University, and who was also not involved in the study, said the study was well done, but it will take more research to push the U.S. Environmental Protection Agency to change its pesticide testing standards as they relate to fish, which are defined by law.