Oral bioavailability of pentachlorophenol from soils of varying characteristics using a rat model

Evidence accumulated during the last two decades suggests that only a fraction of any chemical in soil is available to organisms, and soil-related effects on bioavailability should be considered in optimizing soil remediation cleanup levels. In the current study, the absolute and relative bioavailabilities of pentachlorophenol (PCP) from freshly spiked and environmentally aged soils varying in organic carbon content, clay content, and pH were examined using a rat model. PCP is a broad-spectrum biocide widely used as a wood preservative, and thus is ubiquitous in the environment. Soils and corn oil containing equivalent levels of PCP were administered to male Sprague-Dawley rats by gavage at 2 dose levels: 100 and 200 microg/kg body weight. Equivalent doses were also given intravenously. The areas under the plasma concentration of PCP versus time curves were calculated, and absolute and relative bioavailabilities of PCP from each soil were determined. At a dose of 100 microg/kg body weight, the absolute bioavailabilities of PCP across soils ranged from 36% to 65%, and the relative bioavailabilities ranged from 48% to 82%. At the higher dose level (200 microg/kg body weight), absolute and relative bioavailability ranges were somewhat higher at 46% to 77% and 52% to 87%, respectively. All soils decreased absolute PCP bioavailability significantly at both dose levels and relative bioavailability at the lower PCP dose level. At the higher dose level, only one of the two field-contaminated soils decreased the relative PCP bioavailability. The data indicate that PCP-soil interactions do significantly decrease the oral bioavailability of PCP from soil, but no obvious correlation was observed between soil properties and bioavailabilities.