Elution of polycyclic aromatic hydrocarbons from carbon blacks into biomembranes in vitro

Elution of endogenous polycyclic aromatic hydrocarbons (PAH) from four carbon blacks into biomembranes was investigated in vitro. Membrane systems employed were phospholipid vesicles composed of dimyristoyl phosphatidylcholine (DMPC), rat lung homogenate, and simulated lung surfactant. Amounts of benzo[a]-pyrene which were eluted from carbon blacks were not dependent on the type of membrane, but elution was dependent on the type of carbon black. Elution of B[a]P was detected from only 2 of the carbon blacks and amounts eluted represented only 0.2% to 0.6% of total B[a]P associated with those carbon blacks. The largest amount of B[a]P was eluted from the carbon black with lowest surface area and highest endogenous B[a]P content. Benzo[ghi]perylene also was eluted from carbon blacks though amounts eluted again represented extremely small fractions (0.1-0.2%) of the total on the particles. From these experiments, it appears that only very small quantities of B[a]P and other PAH on carbon blacks are bioavailable.