USGS looks at pyrethroids in urban streams
A study by the US Geological Survey (USGS) has found that contamination of stream sediments with pyrethroid insecticides generally increases with the level of urbanisation. The USGS pilot study sampled sediments at 98 sites in seven metropolitan areas, with streams ranging from undeveloped to highly urbanised basins. It confirmed that pyrethroid insecticides reached levels in urban streams that were toxic to aquatic organisms in laboratory tests, the USGS points out. The varying levels of contamination in relation to urbanisation suggest that different management approaches may be required for different parts of the country to improve stream quality, the Survey concludes.