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.

Accumulation of current‐use and organochlorine pesticides in crab embryos from northern California, USA

“…Bioconcentration factors have been reported for several OCPs in clams, oysters, fish, and other aquatic organisms, but few values have been reported for CUPs. Laboratory-derived BCFs for chlorpyrifos after 7 d of exposure in oysters were 2.3 [6], while BCFs for dichloropropionanilide (DCPA) in clams were 2.1 [2]. Bioconcentration factors of the more water-soluble pesticides are quite a bit lower than the more hydrophobic pesticides, such as dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE), whose BCFs in oysters ranged from 5.0 to 5.5 [2].…”

“…The accumulation of hydrophobic organic chemicals by invertebrates has proven useful in environmental monitoring for polychlorinated biphenyls (PCBs) [1], organochlorine pesticides (OCPs) [2][3][4], polychlorinated benzo-p-dioxins and furans (PCDD/F) [1,5] and organophosphate insecticides (OPs) [3,6,7]. Many of these chemicals are known to cause sublethal effects in aquatic organisms, including reproductive impairment and decreases in hatching success [8][9][10].…”

Bioconcentration, Bioaccumulation, and Metabolism of Pesticides in Aquatic Organisms

“…Reductive debromination of leptophos (71) was reported by Francis et al (1980) in a model ecosystem study. In the metabolism of chlorpyrifos (47) by oysters, the 6-thiomethyl derivative was identified by GC-MS (Woodburn et al 2003). The mercapturic acid or cysteine derivative of (47), produced by GST catalysis and successive enzyme action, is considered to be further transformed successively by C-S β-lyase and thiol methyltransferase.…”