Chemical and Biological Studies of a New Cigarette that Primarily heats Tobacco.Part 3. In Vitro Toxicity of Whole Smoke

Introduction:
This text reports the results of a study comparing the cytotoxic and genotoxic potential of mainstream smoke from three types of cigarettes: a Kentucky reference low tar cigarette (1R4F), a Kentucky reference ultra-low tar cigarette (1R5F), and a test cigarette that primarily heats tobacco (TOB-hT). The study used cellular smoke exposure technology (CSET) to expose Chinese hamster ovary (ChO) cells to whole smoke and measured cytotoxicity using the neutral red assay and genotoxicity using the sister chromatid exchange (SCE) assay.

Key Points:

* The study found that mainstream smoke from 1R5F and TOB-hT cigarettes was significantly less cytotoxic and genotoxic than smoke from the 1R4F cigarette on a per cigarette basis.
* The cytotoxic and genotoxic activity of smoke from TOB-hT cigarettes was slightly greater than the smoke from the ultra-low tar 1R5F reference cigarettes.
* The mainstream whole smoke of the TOB-hT cigarette had slightly greater cytotoxic and genotoxic potential compared with an ultra-low tar 1R5F Kentucky reference cigarette and significantly less activity compared with the whole mainstream smoke from a low tar 1R4F Kentucky reference cigarette.
* The study used the Federal Trade Commission (FTC) smoking regime to smoke the cigarettes.
* The TOB-hT cigarette yields approximately 92% of the WTPM and 77% of the CO yielded by smoking the cigarette to extinction.
* The study used ChO cells, WBL strain, with an average cycle time of 12-14 hours with a modal chromosome number of 21.
* The study used ham's F-12 medium supplemented with 10% FCS, 1% L-glutamine, and gentamicin (50 ng/ml) for cell culture.

Main Message:
The main message of this study is that the TOB-hT cigarette, which primarily heats tobacco, has significantly less cytotoxic and genotoxic activity compared with the whole mainstream smoke from a low tar 1R4F Kentucky reference cigarette. however, the TOB-hT cigarette has slightly greater cytotoxic and genotoxic potential compared with an ultra-low tar 1R5F Kentucky reference cigarette. These findings suggest that the TOB-hT cigarette may be a less harmful alternative to traditional cigarettes, but further research is needed to confirm these results.

Bombick, D.W., P.h. ayres, K. Putnam, B.Reed Bombick, and D.J. Doolittle. “Chemical and Biological Studies of a New Cigarette That Primarily heats Tobacco.Part 3. In Vitro Toxicity of Whole Smoke.” Food and Chemical Toxicology 36, no. 3 (March 1998): 191–97. https://doi.org/10.1016/S0278-6915(97)00155-5.