title: The bioconcentration and metabolism of chlorpyrifos by the eastern oyster, Crassostrea virginica.
abstract: Eastern oysters (Crassostrea virginica) were exposed to [14C]chlorpyrifos (O,O-diethyl-O-[3,5,6-trichloro-2-pyridyl] phosphorothioate) at an average measured seawater concentration of 0.6 microg/L under flow-through conditions for 28 d. The compound O,O-diethyl-O-(3,5-dichloro-6-methylthio-2-pyridyl)phosphorothioate (DMP) was extracted and identified as the single metabolite observed, and this metabolite constituted the majority of the total [14C] activity in the oyster at all sampling times. Once oysters were exposed to clean water, both chlorpyrifos and DMP residues cleared rapidly from whole oysters, with elimination half-lives of <3 d. A simple two-compartment uptake/elimination model was adequate to describe total [14C] activity in whole oysters, edible tissue, and oyster liquor. The average bioconcentration factors (BCFs) for total [14C] activity in whole oysters, edible tissue, and oyster liquor were 565, 1,400, and 35 ml/g, respectively. The parent [14C]chlorpyrifos accumulated to a peak residue concentration of 135 microg/kg in whole oyster tissue, representing an empirical [14C]chlorpyrifos BCF value in the oyster of approximately 225 ml/ g; the BCF value for [14C]chlorpyrifos was lower than the BCF for total [14C] activity in whole oysters and edible tissue because of extensive metabolism to DMP and oyster elimination processes.
authors.affiliation: Dow Chemical Company, Toxicology, Environmental Research and Consulting Laboratory, Midland, Michigan 48674, USA. kbwood@dow.com
authors.forename: Kent B
authors.initials: KB
authors.lastname: Woodburn
authors.forename: Steven C
authors.initials: SC
authors.lastname: Hansen
authors.forename: Gary A
authors.initials: GA
authors.lastname: Roth
authors.forename: Kathryn
authors.initials: K
authors.lastname: Strauss
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D004390:Chlorpyrifos / Q000378:metabolism / Q000493:pharmacokinetics*; D003198:Computer Simulation; D008401:Gas Chromatography-Mass Spectrometry; D006207:Half-Life; D010125:Ostreidae / Q000378:metabolism*; D010573:Pesticide Residues / Q000302:isolation & purification*; D014018:Tissue Distribution; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D002250:Carbon Radioisotopes; D010573:Pesticide Residues; D014874:Water Pollutants, Chemical; D004390:Chlorpyrifos