Rat Lung Tumors Induced by Exposure to Selected Poorly Soluble Nonfibrous Particles

Abstract

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.

Pulmonary Squamous Cyst Induced by Exposure to Indium Arsenide in Hamsters

“…Since pulmonary localized hyperplastic lesion was recognized in both the InAs-and InP-treated animals, but not in GaAs-treated animals in our previous studies [3][4][5] , the main cause of squamous cyst induced by InAs exposure is not arsenic but indium, nevertheless InAs contains arsenic, a potent carcinogen 8) . There is disagreement concerning squamous cysts among researchers, who variously consider squamous cyst to be either a benign tumor or exaggerated squamous metaplasia 9) . Recently Gottschling et al 10) reported that InP particles caused lung tumors when Fischer 344 rats were exposed to the particles for 2 yr.…”

Approaches to carcinogenic risk assessment for polycyclic aromatic hydrocarbons: a UK perspective

“…It is also important to consider the likely enhancing properties of the inflammatory effects of particles on lung tissue when evaluating lung carcinogenicity of PAHs attached to inhaled fine particles. (Baulig et al, 2003;Nikula, 2000;Saito et al, 2002) There is some evidence for a biphasic effect similar to that observed in inhalation studies in the clearance of PAHs administered as solutions via intratracheal instillation to suggest that this is an appropriate surrogate route of administration for inhalation exposure. Thus, Bond et al (1985) administered radiolabeled PAH solutions to rats intratracheally and killed them at various times after instillation to determine the amount of radiolabel retained in the lungs.…”

Titanium dioxide (respirable fraction) [MAK Value Documentation, 2009]

“…By incubating polymorphonuclear leukocytes of humans together with alveolar type II epithelial cells of rats, it was possible to demonstrate that the reactive oxygen species released by leukocytes reach the genome of the epithelial cells, where they induce premutagenic 8-oxo-2'-desoxyguanine adducts (Knaapen et al 1999). As already mentioned, the epithelial cells used, are regarded as primal cells for lung tumours in the rat (Nikula 2000;Nikula et al 1995).…”