PM15 Biomarkers
Exhibit Hall
8:00 AM - Monday
(PM256A) Brain cholinesterase inhibition in juvenile rainbow trout exposed to carbaryl - benchmark concentrations for active ingredient vs formulated products.
Curran, C1, Black, T1, Granger, B1, Guerrette, Z1, Ireland, K1, Marchesini, E1, Schneider, R1, Spradlin, C1, Sternberg, M1, Grassley, J1, Cabarrus, J1, Major, W1, Grue, C1, 1 School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA
ABSTRACT- A variety of pesticides have been detected in surface waters within agricultural and urban areas. In most cases, their biological significance (singly or in combination) to aquatic communities is not known. In the Pacific Northwest, the potential impact of low levels of pesticides in surface waters on efforts to enhance or restore habitats for juvenile and adult salmon is of particular concern. Several of the most commonly reported pesticides are cholinesterase-inhibitors and carbaryl (1-naphthyl N-methylcarbamate; trade name Sevin) is the most commonly reported carbamate. Acetylcholinesterase (AChE) activity in brain tissue is the primary biomarker in fish and wildlife for diagnosing exposure to, and mortality from, pesticides that are cholinesterase-inhibitors. The enzyme is critical for normal nerve function and therefore reductions in enzyme activity may result in changes in physiology and behaviors essential for survival and reproduction. Studies by our laboratory and others suggest that "end products" may be significantly more toxic than active ingredients (ai) alone. Our objectives were: (1) determine dose response curves and threshold concentrations (benchmarks) for AChE inhibition in juvenile rainbow trout (Oncorhynchus mykiss) exposed to carbaryl as active ingredient and two formulated products (Sevin XLR Plus [44.1% ai] and Sevin 80 WSP [80% ai]) for 96-h, (2) determine differences in inhibition between soluble and membrane-bound forms of the enzyme, and (3) compare these values to concentrations reported in surface waters. Results suggest that benchmarks are ca. 15 ppb ai for the formulated products and technical grade material with inhibition similar between the soluble and membrane-bound forms at concentrations ≥15 ppb. An increase in AChE activity (hormesis) was observed at 6.3 ppb
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