Rat lung tumors induced by exposure to selected poorly soluble nonfibrous particles.

Rodent bioassays have been used to assess the carcinogenicity of several inhaled, poorly soluble, nonfibrous particles that vary in toxicity and carcinogenic potency. There is substantial published information from chronic inhalation bioassays of diesel exhaust, carbon black, titanium dioxide, talc, and coal dust. This review summarizes data from studies with exposures for 2 yr or more using these 5 materials. The review has four objectives: (1) to summarize the current information available from these bioassays concerning exposure-dose-carcinogenic response in rats, (2) to summarize the pathologic and phenotypic features of the neoplastic response in rats, (3) to examine possible strain- and gender-related differences, and (4) to compare the neoplastic responses of rat to those of other species exposed to these materials.