T9 PM Pyrethroid Insecticides in Urban and Agricultural Environments
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 339-340

(DOB-1117-556378) The toxicity of synthetic pyrethroids to freshwater and estuarine sediment dwelling organisms.

Putt, A¹, Dix, M¹, Tavano, J¹, Dobbs, M², PWG, ³, ¹ Springborn Smithers Laboratories, Wareham, MA, USA² Bayer CropScience, Research Triangle Park, NC, USA³ Bayer Crop Science, Du Pont Crop Protection, FMC Corporation, Pytech Chemicals GmbH, Valent USA Corporation, Syngenta AG

ABSTRACT- Nine sediment toxicity tests were conducted with four synthetic pyrethroids, bifenthrin, cyfluthrin, cypermethrin, and esfenvalerate, under GLP following EPA standard methods. Separate 10-day sediment toxicity tests (EPA Test Method 100.2) were conducted with all four compounds in the same freshwater sediment to evaluate the impact on survival and growth of the freshwater midge larvae, Chironomus tentans. In addition, a life cycle test (EPA Test Method 100.5) was conducted with cypermethrin in the same freshwater sediment to evaluate the impact on survival, growth, emergence and reproduction of C. tentans. Separate 28-day sediment toxicity tests (EPA 600/R-01/020) were conducted with each pyrethroid in the same estuarine sediment to evaluate the impact on survival and growth on the estuarine amphipod, Leptocheirus plumulosus. LC50, EC50 and No-Observed Effect Concentrations were calculated based on measured sediment concentrations. In the 10-day midge studies, LC50 values ranged from 280 to >2500 g/kg, while EC50's ranged from 220 to 780 g/kg. Growth was the most sensitive parameter in the midge life-cycle study with clear effects seen in body weight at 100 g/kg. L. plumulosus, with a 28-d exposure, was in general more sensitive then C. tentans (10 days) with LC50 values in the range of 34 and 240 g/kg, and EC50's in the range of 36 to 150 g/kg. Trends regarding species and parameter sensitivity will be discussed as well as expression of results in a manner more reflective of the bioavailable fraction (e.g., sediment concentrations normalized for sediment organic carbon).

Key words: Pyrethroid, Toxicity, Chironomus tentans, Leptocheirus plumulosus