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(M/MF137) Cytotoxicity guided risk estimation of polluted soils. Ragnvaldsson, Daniel1, 2, Leffler, Per1, 1 2 ABSTRACT- Extracts of contaminated soils from four different areas in Sweden were tested for their cytotoxicity in a L-929 cell-line (mouse lung fibrocyte). Differences in cell numbers (neutral red assay) after 72 hours of exposure, was used as toxicological endpoint. Two of the soils tested came from extensively industrialized sites: Bohus-Eka (chlor-alkali factory; mixed mercury and PAHs), and Husarviken (gasworks; mainly heavy PAHs). Furthermore, a municipal waste sludge from Stockholm (broad spectrum mixed pollutants) and a coastal PCB-sediment (PCB polluted fibre dump) were included in this study. Three different extraction methods were used, all with water as a solvent; 1, extraction at 26 degrees C on a shake-board for 96 hours; 2, extraction at 50 degrees C on a shake-board for 14 hours; 3, pressurized liquid extraction (PLE) at 200 degrees C and 20 MPa. The relative toxicity between treatments revealed differences due to sampling site as well as extraction method. All extracts induced a concentration related decrease in cell viability within 72 hours of exposure. The use of higher extraction temperature, in soils with mainly hydrophobic pollutants, increased the toxic effect probably because of higher extraction yield. This indicated that all soils contained toxic fractions of pollutants made bioavailable by the different water extractions. Although chemically yet poorly defined, the studied soils were ranked based on their toxicological characteristics. Key words: Cytotoxicity, Risk estimation, Polluted soil, Neutral red assay |
