South Atlantic Water Science Center - Georgia
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Assessment of pyrethroid pesticides in watersheds of variable land use in Georgia
Pyrethroid insecticides have been in use for many years in the U.S., but their use in urban and in agricultural areas of the Southeastern U.S. is increasing over the past few years because of regulatory restrictions on organochlorine, organophosphate and carbamate pesticides, the effectiveness that pyrethroid insecticides have been demonstrated to have in controlling insect pests, and the low toxicity that pyrethroids have to mammalians (Elliott, 1976; Elliott and others, 1978; Casida, 1980). The USGS-National Water Quality Assessment Program (NAWQA) has documented reductions in concentrations of compounds such as diazinon in urban streams, but a key unanswered question is whether the increased use of pyrethroid insecticides is of concern for aquatic health (U.S. Geological Survey, 1999; Gilliom and others, 2006; Hladik and Kuivila, 2008a).
Toxicological and environmental studies have shown that many of the commonly used pyrethroids have significant non-target toxicity to beneficial insects, fish, and invertebrates when these compounds reach the aquatic environment (Ingersoll and others, 2001; MacDonald and others, 2000). A recent national study of urban bed sediments has found a forty percent occurrence of a commonly used pyrethroid, bifenthrin, in urban and rural sediments, including a sixty percent occurrence in Atlanta urban streams (Moran and others, 2008; Hladik and others, 2008b). Concentrations measured in environmental samples are known to be toxic to aquatic invertebrates under laboratory conditions (Kemble and others, 2008). This USGS and Georgia Department of Agriculture cooperative study will provide a basic status assessment of the types and levels of pyrethroids found in stream water and bed sediments from watersheds ranging from rural to agricultural and to urban land use. Samples will be taken over multiple seasons to determine if fluctuations in use can coincide with levels found in streams.
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