Evaluation of coal liquids derived from the EDS process in carcinogenesis screening tests

Four process streams derived from the EDS not equal to direct coal liquefaction process were evaluated in two in vitro assays to screen for carcinogenic potential: the Salmonella/mammalian microsome mutagenicity assay and the Syrian hamster embryo morphologic transformation assay. Three high boiling liquids (two recycle solvents, nominal boiling range 200-425 degrees C; and a fuel oil blend, nominal boiling range 200-538 degrees C) were active in both assays. A hydrotreated naphtha sample (< 200 degrees C) was not active in either. The Salmonella data agreed qualitatively with results of dermal carcinogenesis studies; however, quantitative differences as measured by the estimation of mutagenic potency were apparent. The lack of quantitative agreement may have been related to the fact that the dermal carcinogenic activity of coal-derived synthetic fuels is predominantly associated with neutral polycyclic aromatic hydrocarbons, whereas activity in the Salmonella assay is strongly influenced by the presence of aromatic amines and nitroaromatic compounds. Two modifications of the Salmonella assay--detergent dispersion and hamster S9 activation--were examined. These techniques improved assay performance for some but not all of the coal liquids. The differences in response may have been related to compositional differences in the various liquids.