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Benzo[ a ]pyrene bioavailability from pristine soil and contaminated sediment assessed using two in vitro models
Author(s) -
Vasiluk Luba,
Pinto Linda J.,
Walji Zahra A.,
Tsang Wing Shan,
Gobas Frank A.P.C.,
Eickhoff Curtis,
Moore Margo M.
Publication year - 2007
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/06-343r.1
Subject(s) - bioavailability , desorption , pyrene , sorption , chemistry , environmental chemistry , organic matter , sediment , persistent organic pollutant , matrix (chemical analysis) , chromatography , hydrocarbon , adsorption , organic chemistry , biology , pharmacology , paleontology
A major route of exposure to hydrophobic organic contaminants (HOCs), such as benzo[ a ]pyrene (B a P), is ingestion. Matrix‐bound HOCs may become bioavailable after mobilization by the gastrointestinal fluids followed by sorption to the intestinal epithelium. The purpose of this research was to measure the bioavailability of [ 14 C]‐B a P bound to pristine soils or field‐contaminated sediment using an in vitro model of gastrointestinal digestion followed by sorption to human enterocytes (Caco‐2 cells) or to a surrogate membrane, ethylene vinyl acetate (EVA) thin film. Although Caco‐2 cells had a twofold higher lipid‐normalized fugacity capacity than EVA, [ 14 C]‐B a P uptake by Caco‐2 lipids and EVA thin film demonstrated a linear relationship within the range of B a P concentrations tested. These results suggest that EVA thin film is a good membrane surrogate for passive uptake of B a P. The in vitro system provided enough sensitivity to detect matrix effects on bioavailability; after 5 h, significantly lower concentrations of [ 14 C]‐B a P were sorbed into Caco‐2 cells from soil containing a higher percentage of organic matter compared to soil with a lower percentage of organic matter. The [ 14 C]‐B a P desorption rate from Caco‐2 lipids consistently was twofold higher than from EVA thin film for all matrices tested. The more rapid kinetics observed with Caco‐2 cells probably were due to the greater surface area available for absorption/desorption in the cells. After 5 h, the uptake of B a P into Caco‐2 lipid was similar in live and metabolically inert Caco‐2 cells, suggesting that the primary route of B a P uptake is by passive diffusion. Moreover, the driving force for uptake is the fugacity gradient that exists between the gastrointestinal fluid and the membrane.