MOBILIZATION OF PAH AND PCB FROM CONTAMINATED SOIL USING A DIGESTIVE-TRACT MODEL

Environmental contaminants are mainly incorporated by ingestion. In ge neral only those contaminants mobilized by the digestive juices are av ailable for absorption in the digestive tract, while pollutants still fixed to indigestible particles leave the body without any effect. To evaluate the different health risks arising from the ingestion of indi vidual types of polluted soil or other materials, we developed an in v itro test system which simulates the transition of pollutants from con taminated materials into digestive juices by means of a standardized a rtificial gastro-intestinal model. The test system simulates the influ ence of the acidic environment of the stomach (gastric model) followed by the neutral or slightly alkaline environment of the small intestin e (gastro-intestinal model). Investigations on small amounts of pollut ed soil, sewage sludge, asphalt, metal scrap and blast sand showed tha t the mobilization of polycyclic aromatic hydrocarbons (PAH) and polyc hlorinated biphenyls (PCB) by artificial gastric juice reaches 3% up t o 22% of the pollutant concentration introduced into the test system. Elutions of the contaminated materials under gastric and subsequently under intestinal conditions with bile concentrations of 3 g/l resulted in PAH- and PCB-mobilizations in the range of 5% up to 40%. The degre e of mobilization depends considerably on supplementary food material added to the test system. Lyophilized milk increased the fraction of m obilized PAH and PCB to 40%-85%. Application of the test system on 22 different contaminated soils showed that the mobilization of PAH under gastro-intestinal conditions with the addition of lyophilized milk ra nged from 7% up to 95%, and the mobilization of PCB ranged from 32% up to 83%. This indicates that the test system can be a useful tool for evaluating the individual health risks arising from polluted soil or o ther materials.