title: Contaminated soils (I): In vitro dermal absorption of benzo[a]pyrene in human skin.
abstract: Dermal absorption of the lipophile and potential carcinogen benzo[a]pyrene (BaP) in soils from contaminated sites was simulated in vitro using human skin exposed to 14C-BaP-spiked soil. This study is the first in a series of tests at Health Canada with several soil contaminants spanning a wide range of lipophilicity conducted with viable human skin. Breast skin was obtained fresh from a local hospital and dermatomed to a thickness of 0.4-0.5 mm. Teflon Bronaugh diffusion cells were perfused with HEPES buffered Hanks saline (pH 7.4) with 4% bovine serum albumin (BSA) and fractions were collected at 6-h intervals for up to 24 h exposure either to 14C-BaP applied in acetone or spiked in a commercial gardening soil. As skin depot 14C levels were still high at 24 h, the study was repeated for up to 42 h to examine skin depot bioavailability. Skin was washed with soapy water at 24 h in both the 24- and 42-h studies. Exposure to 14C-BaP both with and without soil was conducted in triplicate with skin specimens from at least 4 patients. In the 24-h exposure tests including the skin depot there was 15 and 56% absorption with and without soil, respectively. The lower total percent absorption from the spiked soil applied to skin resulted from lower depot absorption of 8% with and 45% without soil. Data for 42-h studies were similar and revealed no significant decrease in skin depot levels. Including the 42-h depots there was 16 and 50% absorption with and without soil, respectively, with respective depots of 7 and 39%. As there was no significant difference between the 24- and 42-h depots both with and without soil, the data suggest the depot for BaP was not bioavailable for at least the additional 18-h post soap wash exposure. The bioavailability of BaP is discussed in relation to previous in vitro and in vivo studies in perspective with dermal exposure to contaminated soils.
authors.affiliation: Health Canada, Environmental Occupational and Toxicology Division, Systemic Toxicology and Pharmacokinetics Section, Ottawa, Ontario, Canada. rick_moody@hc-sc.gc.ca
authors.forename: Richard P
authors.initials: RP
authors.lastname: Moody
authors.forename: Julie
authors.initials: J
authors.lastname: Joncas
authors.forename: Mark
authors.initials: M
authors.lastname: Richardson
authors.forename: Ih
authors.initials: I
authors.lastname: Chu
mesh_terms: D001564:Benzo(a)pyrene / Q000493:pharmacokinetics*; D001682:Biological Availability; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D012869:Skin Absorption; D012989:Soil Pollutants / Q000493:pharmacokinetics*
chemical_list: D012989:Soil Pollutants; D001564:Benzo(a)pyrene