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Enantiomer specific measurements of current-use pesticides in aquatic systems
Citation:
Ulrich, E., L. McMillan, Q. Wang, T. Albertson, G. Cho, K. Kuivila, W. Lao, S. Peoples, R. Rief Lopez, AND P. TenBrook. Enantiomer specific measurements of current-use pesticides in aquatic systems. Presented at IUPAC International Congress of Pesticide Chemistry, San Francisco, CA, August 10 - 14, 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:
Contrary to predictions, current-use pesticides are adversely affecting aquatic systems in both urban and agricultural watersheds, particularly in California. One possible divergence from fate and effect predictions is that some current-use pesticides are chiral molecules. Increased non-target toxicity may be caused by increased concentration of a more toxic pesticide enantiomer in the environment. 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. This research developed a 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 sets of environmental samples including lab dosed salmon, California aquatic systems such as concrete runoff, sediment, river, surface, storm, and wastewater. 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. Complete analysis of the data will give indications whether chirality may explain adverse impacts in aquatic systems.