Comparative Subchronic Inhalation Bioassay in Hamsters of a Cicarette that only Heats Tobacco

Abstract

This subchronic inhalation study compared the effects of nose-only exposure in hamsters to the smoke from the University of Kentucky 1R4F reference cigarette, which burns tobacco, and a test cigarette, which only heats tobacco. Thirty-four Syrian golden hamsters per sex per group were exposed to either reference or test smoke at 0, 120, 350, or 640 pg wet total particulate matter (WTPM)/l of air, 1 h/day, 5 days/wk. Of these 34 hamsters, 9 hamsters/sex/group were evaluated for respiratory flow, blood carboxyhemoglobin, and plasma nicotine and coining during the first 12 wk of exposure and then killed. Another 75 of the 34 hamsters/sex/group were killed and evaluated after 13 wk of exposure (Basic Study); the remaining 10 hamsters/sex/group were held without smoke exposure for an additional 6 wk (Recovery Croup). Clinical appearance, mortality body and selected organ weights, and gross and histologic changes were examined in hamsters killed after 13 wk of exposure and 6 wk after cessation of exposure. Hematologic and clinical chemistry parameters were examined in hamsters killed after 13 wk of exposure. The test tobacco smoke produced significantly fewer and less pronounced biological changes than the reference tobacco smoke. Histologic changes were either absent or less frequent and less pronounced in the test tobacco smoke groups. Microscopic lesions regressed completely in all test tobacco smoke groups and completely or partially in the reference tobacco smoke groups after 6 wk of recovery.