Abstract
High‐boiling coal liquids from the solvent‐refined coal‐I and ‐II (SRC‐I, ‐II) processes, respectively, were fractionally distilled. In the case of SRC‐I process solvent (PS), 50°F distillation cuts were obtained between 550 and 850°F, while for the SRC‐II material, the 50°F cuts were only obtained between 700 and 850°F. These cuts, as well as the parent material, were tested for their ability to initiate skin tumors by applying a single dose (25 mg) to the shaved backs of Charles River female CD‐1 mice. After 2 weeks, the mice received twice weekly applications of 5 μg of the promoter, phorbol myristate acetate. Only a few tumors were found for SRC‐I fractions boiling below 700°F; tumor‐initiating activity increased as the boiling point increased. A similar increase in response with increasing boiling point was seen for the SRC‐II cuts. The initiating activities for the parent materials were similar to those observed for their respective 800 to 850°F cuts.