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Enantiomer Specific Measurements of Current-use Pesticides in Aquatic Systems (#2)
Citation:
Ulrich, E., L. McMillan, Q. Wang, T. Albertson, G. Cho, K. Kuivila, W. Lao, S. Peoples, R. Lopez, AND P. TenBrook. Enantiomer Specific Measurements of Current-use Pesticides in Aquatic Systems (#2). SETAC (Society of Environmental Toxicology and Chemistry), Vancouver, BC, CANADA, November 09 - 13, 2014.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
Research has shown that current-use pesticides can enter urban and agricultural watersheds and adversely affect aquatic organisms. A potential cause may be higher concentrations of the more toxic pesticide enantiomer present in the pesticide mixture. The presence of pesticide enantiomers is dictated by the formulation (e.g., racemic or enriched), transport and degradation rates (usually stereoselective if biotic, non-selective if abiotic) which can vary between the mirror images. We developed a new GC/MS method for stereoisomer-specific analysis of the current-use pesticides fipronil, cis-bifenthrin, cis-permethrin, cypermethrin, and cyfluthrin. Single enantiomer standards were obtained for the first four compounds to allow a direct link to enantiomer toxicity. The method was applied to several different sets of extracts including lab dosed salmon and various environmental media (concrete runoff, sediment, river-, surface-, storm-, and waste- water) that were collected from California aquatic systems. Preliminary data in dosed fish shows that cis-bifenthrin enantiomer fractions (EF) are statistically different from racemic standards (P <0.001). The EF for standards ranges 0.466-0.521 and 0.378-0.490 for fish, with all but 3 of 23 fish samples having EFs lower than standards. In a study of runoff from concrete where both bifenthrin and permethrin were applied, preliminary EFs were calculated for 12 and 22 samples, respectively, out of 28 total. Bifenthrin EFs were not statistically different than racemic standards (P>0.21), however, cis-permethrin EFs were statistically different (P <0.005) than racemic standards with 7 of 22 sample EFs outside the range for standards. Complete analysis of the data will give indications whether chirality may explain adverse impacts in aquatic systems.