Epidermal carcinogenesis studies of EDS liquids.

A series of liquids representing different potential design options or operating configurations for the EDS direct coal liquefaction process* were evaluated for skin cancer potential. All of the samples that contained substantial amounts of material boiling above 370 degrees C were active dermal carcinogens; tumor yields were near 100% and median times to tumor development generally ranged from 30 to 40 weeks. Two liquids that boiled below ca. 200 degrees C were tested and each produced one squamous cell tumor. These data suggested that high-boiling-point, coal-derived liquids are likely to be relatively potent dermal carcinogens; whereas low-boiling-point liquids do not possess significant carcinogenic potential. Based on a comparison of the carcinogenic potency data, liquids produced by the EDS process apparently do not present a significantly greater dermal carcinogenic hazard than other coal-derived materials of similar boiling range.