title: Bioaccessibility of PAHs in Fuel Soot Assessed by an in Vitro Digestive Model with Absorptive Sink: Effect of Food Ingestion.
abstract: We investigated the effects of changing physiological conditions in the digestive tract expected with food ingestion on the apparent bioaccessibility (Bapp) of 11 polycyclic aromatic hydrocarbons (PAHs) in a fuel soot. A previously established in vitro digestive model was applied that included silicone sheet as a third-phase absorptive sink simulating passive transfer of PAHs to intestinal epithelium in the small intestine stage. The Bapp is defined as the fraction found in the digestive fluid plus sheet after digestion. We determined that Bapp was independent of gastric pH and addition of nonlipid milk representing dietary proteins and carbohydrates, whereas it increased with bile acids concentration (2.0-10 g/L), small intestinal pH (5.00-7.35), and addition of soybean oil representing dietary lipid (100% and 200% of the mean daily ingestion by 2-5 year olds in the U.S.). Bapp of PAHs increases with small intestinal pH due to the combined effects of mass transfer promotion from nonlabile to labile sorbed states in the soot, weaker sorption of the labile state, and increasingly favorable partitioning from the digestive fluid to the silicone sink. Under fed conditions, Bapp increases with inclusion of lipids due to the combined effects of mass transfer promotion from nonlabile to labile states, and increasingly favorable partitioning into bile acid micelles. Our results indicate significant variability in soot PAH bioaccessibility within the range of physiological conditions experienced by humans, and suggest that bioaccessibility will increase with coconsumption of food, especially food with high fat content.
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, P.R. China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Environmental Sciences, The Connecticut Agricultural Experiment Station , New Haven, Connecticut 06504-1106, United States.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Pignatello
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, P.R. China.
authors.forename: Shu
authors.initials: S
authors.lastname: Tao
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003-9246, United States.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D001647:Bile Acids and Salts; D001682:Biological Availability; D004063:Digestion / Q000502:physiology; D004435:Eating; D041981:Gastrointestinal Tract / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007421:Intestine, Small / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000493:pharmacokinetics*; D012828:Silicones; D053260:Soot / Q000737:chemistry*; D013024:Soybean Oil / Q000494:pharmacology
chemical_list: D001647:Bile Acids and Salts; D011084:Polycyclic Aromatic Hydrocarbons; D012828:Silicones; D053260:Soot; D013024:Soybean Oil