The risks associated with tobacco products vary significantly with the type of product used and how it is consumed. A recent two-year study of the toxicity and carcinogenicity of smokeless tobacco products completed at Battelle is helping the industry understand the risks associated with oral exposure to ever-evolving tobacco formulations. The results were published in the October edition of Experimental and Toxicologic Pathology.
The comprehensive two-year oral chronic toxicity/carcinogenicity study, conducted in collaboration with researchers from the R.J. Reynolds Bowman Gray Technical Center, assessed the effects of smokeless tobacco on rodents. The test groups consisted of a tobacco blend used in snus and an aqueous tobacco extract of the same blend. Subjects were exposed to dosages of tobacco chosen to simulate potential exposure for humans ingesting smokeless tobacco or an aqueous extract of smokeless tobacco (the latter intended to simulate a snus extract, to enable bridging these data to snus epidemiology data).
Over the course of the two-year study, clear treatment-related, dose-responsive effects were observed including: (1) increases in plasma nicotine and cotinine (indicating that animals were appropriately exposed to levels relevant to human exposure) and (2) decreases in body weights. In addition, two tumor types displayed statistically significant increases in the experimental groups vs. controls: (1) uterine carcinoma in females and (2) epididymal mesothelioma in males. Three tumor types displayed statistically significantly decreased incidence trends: (1) mammary gland adenomas in females, (2) skin basal cell carcinomas in females, and (3) thyroid follicular cell adenomas in males. These increases (and decreases) in tumor trends were interpreted as not being treatment-related because: (1) there were no preneoplastic or related nonneoplastic histopathological findings in the treated rats at the 1-year or 2-year time points to suggest that any of these neoplastic findings were treatment-related, and (2) the tumor morphologies and incidences were generally within the expected range of historical controls for Wistar Han rats. Findings from this study indicate that chronic exposure of male and female Wistar Han rats to either a tobacco blend used in snus or a tobacco extract of that blend does not lead to increased toxicity or carcinogenicity, based on the specified outcomes measured.
Access the complete study here: Toxicological evaluation of smokeless tobacco: 2-year chronic toxicity and carcinogenicity feeding study in Wistar Han rats.