Abiotic transformation of chlorpyrifos to chlorpyrifos oxon in chlorinated water.

Roles of uptake, biotransformation, and target site sensitivity in determining the differential toxicity of chlorpyrifos to second to fourth instar Chironomous riparius (Meigen).

Early life stages of aquatic organisms tend to be more sensitive to various chemical contaminants than later life stages. This research attempted to identify the key biological factors that determined sensitivity differences among life stages of the aquatic insect Chironomous riparius. Specifically, second to fourth instar larvae were exposed in vivo to both low and high waterborne concentratio...

Transformation of chlorpyrifos and chlorpyrifos-methyl in prairie pothole pore waters.

Non-point source pesticide pollution is a concern for wetlands in the prairie pothole region (PPR). Recent studies have demonstrated that reduced sulfur species (e.g., bisulfide and polysulfides) in PPR wetland pore waters directly undergo reactions with chloroacetanilide and dinitroaniline compounds. In this paper, the abiotic transformation of two organophosphate compounds, chlorpyrifos and c...

In vitro age-dependent enzymatic metabolism of chlorpyrifos and chlorpyrifos-oxon in human hepatic microsomes as well as chlorpyrifos-oxon in plasma

Purification of two rat hepatic proteins with A-esterase activity toward chlorpyrifos-oxon and paraoxon.

A-esterases are calcium-dependent hydrolases that can detoxify the active metabolites (oxons) of organophosphorus insecticides such as chlorpyrifos and parathion. A-esterases from rat liver have previously been shown to hydrolyze chlorpyrifos-oxon but not paraoxon at low substrate concentrations. Two A-esterases were extracted by ammonium sulfate fractionation from solubilized rat liver microso...

Rat brain CYP2B-enzymatic activation of chlorpyrifos to the oxon mediates cholinergic neurotoxicity.

Chlorpyrifos is a commonly used insecticide that can be metabolically activated by CYP2B to the acetylcholinesterase inhibitor chlorpyrifos-oxon causing cholinergic overstimulation and neurotoxicity. Rat brain extracts can also activate chlorpyrifos in vitro, and the lack of circulating oxon in serum suggests that metabolic activation within the brain may be responsible for chlorpyrifos neuroto...