M11 PM Internal Exposure
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 343-344

(GAN-1116-367640) Bioavailability of Pyrethroid Insecticides in Surface Water and Sediments.

Gan, J¹, Yang, W¹, Hunter, W¹, Spurlock, F², ¹ University of California Riverside, Riverside, CA² California Department of Pesticide Regulations, Sacramento, CA

ABSTRACT- Synthetic pyrethroids are widely used insecticides in both urban and agricultural environments, and are also important alternatives to the popular organophosphates diazinon and chlorpyrifos. Recent studies reported frequent detections of trace levels of pyrethroids in sediments or runoff effluents at many sites in California. However, although pyrethroids have high and broad spectrum of aquatic toxicity, they are also essentially insoluble in water and have outstanding affinity for solids and dissolved organic matter (DOM). These properties suggest that association with the sediment phase and DOM will likely negate the actual toxicity of pyrethroids in the aquatic environments. However, the bioavailability of pyrethroids in the multi-phase aquatic matrices is poorly understood. In this study, we used both manual solid phase microextraction (SPME) and the biomimetic polydimethylsiloxane (PDMS) fiber method to measure bioavailable fractions of pyrethroids in sediment and surface water samples. The measured concentrations were further correlated with uptake of ¹⁴C-labelled compounds by D. magna or C. tentans, and acute toxicity to C. dubia and D. magna. This presentation will give an overview of the developed procedures and a summary of the observed effects of DOM and suspended solids on ecotoxicological end-points of several pyrethroids. This information will be valuable for developing ecotoxicologically relevant monitoring methods and water quality standards.

Key words: Bioavailability, Internal exposure, Biomimetic sampling, SPME