Quantifying the presence of current-use insecticides and toxicity of sediments in urban residential watersheds in central Texas.

In the US, residential use of pyrethroid and other recently developed insecticides has increased substantially in recent years, yet the impact of these insecticides on benthic invertebrates in urban streams is largely unknown. The objective of this study was to determine the presence and concentration of current-use pesticides in the sediments of residential streams in central Texas. Additionally, the toxicity of these sediments to Hyalella azteca was evaluated. Sediment samples were collected from several sites in urban streams over the course of a pesticide application season. The sediments were extracted and analyzed using a Varian 2100 gas chromatograph with MS/MS for the presence of several pyrethroids and other common insecticides. Ten-day sediment toxicity tests using H. azteca were also conducted with the sediment samples. Results of this study suggest that pyrethroid insecticide contamination of urban sediments may indeed be a concern in central Texas.