Studies estimating the dermal bioavailability of polynuclear aromatic hydrocarbons from manufactured gas plant tar-contaminated soils

In vitro percutaneous absorption studies were performed with contaminated soils or organic extracts of contaminated soils collected at manufactured gas plant (MGP) sites. The MGP tar contaminated soils were found to contain a group of targeted polynuclear aromatic hydrocarbons (PAH) at levels ranging from 10 to 2400 mg/kg. The soil extracts contained target PAH at levels ranging from 12000-34000 mg/kg. Dermal penetration rates of target PAH from the MGP tar-contaminated soils/soil extracts were determined experimentally through human skin using H-3-benzo[a]pyrene (BaP) as a surrogate. Results from three MGP sites showed reductions of 2-3 orders of magnitude in PAH absorption through human skin from the most contaminated soils in comparison to the soil extracts. Reduction in PAH penetration can be attributed to PAH concentration and (soil) matrix properties. PAH dermal flux Values are used to determine site-specific dermally absorbed dose (DAD) and chronic daily intake (CDI) which are essential terms required to estimate risk associated with human exposure to MGP tar and MGP tar-contaminated soils.