Environmental Health - Toxic Substances
Pyrethroid Insecticide Contamination of Streams Increases with Urbanization
Contamination and toxicity in streambed sediments caused by pyrethroid insecticides generally increased with the degree of urbanization in seven metropolitan areas across the Nation, according to a U.S. Geological Survey (USGS) study recently published in Environmental Science and Technology. Pyrethroids are a group of synthetic insecticides similar to the natural pesticide pyrethrum—produced by chrysanthemum flowers – but in a much more potent form - that are used to control insect pests. USGS scientists tested for 14 commonly used pyrethroid insecticides in 98 streams within the following metropolitan areas: Atlanta, Boston, Dallas, Denver, Milwaukee-Green Bay, Salt Lake City, and Seattle. The scientists conducted laboratory toxicity tests on sediments from the streams, and the tests showed that pyrethroid insecticides did reach levels that were toxic to aquatic organisms. The scientists observed decreased survival of test organisms (the amphipod Hyalella azteca) in approximately one-quarter of the sediment samples, which is likely due to the presence of pyrethroid insecticides. The U.S. Environmental Protection Agency (USEPA) is working with the California Department of Pesticide Regulation to reevaluate certain pesticide products containing pyrethroids. This study will provide additional information to the USEPA and to water-resource and wildlife managers about the occurrence and environmental impacts of pyrethroids in urban streams across the Nation.
Pyrethroids Found in Agricultural Streams Too
In a companion study, USGS scientists found that pyrethroid insecticides were also found in streams draining agricultural areas and that the pyrethroids found were generally consistent with the ones applied in the stream's watershed. The toxicity and number of pyrethroids detected in streambed sediments were higher in urban streams; however, the concentrations of individual pyrethroids in both urban and agricultural streams were similar. This follow-on study was funded by USGS Toxic Substances Hydrology Program and National Water-Quality Assessment (NAWQA) Program.
Kuivila, K.M., Hladik, M.L., Ingersoll, C.G., Kemble, N.E., Moran, P.W., Calhoun, D.L., Nowell, L.H., and Gilliom, R.J., 2012, Occurrence and potential sources of pyrethroid insecticides in stream sediments from seven U.S. metropolitan areas: Environmental Science and Technology, v. 46, no. 8, p. 4297-4303, doi:10.1021/es2044882.
Moran, P.W., Calhoun, D.L., Nowell, L.H., Kemble, N.E., Ingersoll, C.G., Hladik, M.L., Kuivila, K.M., Falcone, J.A., and Gilliom, R.J., 2012, Contaminants in stream sediments from seven U.S. metropolitan areas--Data summary of a national pilot study: U.S. Geological Survey Scientific Investigations Report 2011-5092, 66 p.
Hladik, M.L., and Kuivila, K.M., 2012, Pyrethroid insecticides in bed sediments from urban and agricultural streams across the United States: Journal of Environmental Monitoring, v.14, p. 1838-1845, doi:10.1039/C2EM10946H