In this study, USGS researchers looked for 14 commonly-used pyrethroid insecticides in 98 streams across the following metropolitan areas: Atlanta, Boston, Dallas, Denver, Milwaukee-Green Bay, Salt Lake City, and Seattle. Pyrethroid insecticides reach urban streams in rainwater, storm drainage, or irrigation runoff. The metropolitan areas studied had varying levels of contamination in relation to urbanization which suggests that different management approaches may be required for different parts of the country to effectively improve stream quality.
"No one wants to have a beautiful summer evening in the backyard ruined by hungry mosquitos, and yet this new USGS study indicates that these insecticide applications are not limited to the pesky target of interest," said USGS Director Marcia McNutt. "The sum total of these applications across many urban outdoor areas is running off into nearby streams, where the chemicals are toxic to aquatic organisms that we never meant to harm."