Inhalation studies with benzo[a]pyrene in Syrian golden hamsters.

Groups of Syrian golden hamsters were exposed by inhalation to benzo[a]pyrene (BP) in concentrations of 2.2, 9.5, and 45.6 mg/m3 air. Although 45.6 mg BP/m3 air was carcinogenic and toxic, 2.2 mg BP/m3 air led to no neoplastic response. The highest tumor incidence was seen in the group exposed to 9.5 mg BP/m3 air. Average survival times were similar in the controls (not exposed to BP) and in the 2 groups given 2.2 and 9.5 mg BP/m3 air. Exposure-related neoplasms were found in the nasal cavity, larynx, pharynx, esophagus, and forestomach. Bronchogenic tumors did not develop.