Mobilization of PCBs and lindane from soil during in vitro digestion and their distribution among bile salt micelles and proteins of human digestive fluid and the soil

Children can take up contaminated soil via hand-to-mouth behavior. The cont aminants can be mobilized from the soil by digestive juices and thus become available for intestinal absorption (i.e. become bioaccessible). In the pr esent study components of an in vitro digestion model were varied to study their effect on the mobilization of several PCBs and lindane from surrogate soil (OECD-medium). Approximately 35% of the PCBs and 57% of lindane were bioaccessible after a default digestion. Since the mobilization was indepen dent of the spiking level, a partitioning-based model could describe the di stribution of the test compounds. Fitting the data to the model yielded a r atio of partitioning coefficients that indicated that approximately 60% of the PCBs were sorbed to the OECD-medium, 25% to bile salt micelles, and 15% to proteins. The respective values for lindane were 40%, 23%, and 32%. The relatively large fraction of the mobilized compounds that was sorbed to bi le salt micelles indicates that micelles play a central role in making hydr ophobic compounds bioaccessible. The distribution model is suitable for exp laining the results reported in several literature studies and can be used to extrapolate the physiological parameters for the worst case situation an d trends in the bioaccessible fraction.