Development of a Biokinetic Model to Evaluate Dermal Absorption of Polycyclic Aromatic Hydrocarbons from Soil

Abstract

The high carcinogenic potency of polycyclic aromatic compounds often results in the dermal pathway indicating significant risk to human health at sites with contaminated soils, resulting in the establishment of conservative, risk-based remediation goals. The sorptive properties of soil sequester chemical contaminants, making them less available for uptake by receptors. Recent studies of desorption from soil indicate that PAHs follow a nonlinear desorption pattern that can be estimated by two phases: a rapid, followed by a slow, desorbing fraction. In this work, we adapt a fugacity-based model to evaluate the availability of polycyclic aromatic hydrocarbons (PAHs) from soil to human skin. Incorporating two-site desorption kinetics into the fugacity model renders a less available fraction of chemical in soil for absorption, decreasing predicted dermal uptake. We explore the impacts to dermal bioavailability of removing the “fast-desorbing” fraction of chemical from the soil. The model predicts uptake within a factor of two when compared with experimental data on dermal uptake. Soil moisture and soil loading rates emerge as potential limiting variables; however, the model is most sensitive to the size of the fast desorbing fraction of chemical in soil