Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 2. In vitro toxicology of mainstream smoke condensate

Introduction:
This text is a scientific study comparing the genotoxic and cytotoxic potential of mainstream cigarette smoke condensate (CSC) from a new cigarette that primarily heats tobacco (TOB-hT) with that of CSC from a Kentucky reference low ‘‘tar’’ cigarette (1R4F) and a Kentucky reference ultra-low ‘‘tar’’ cigarette (1R5F). The study uses a battery of in vitro toxicology tests including sister chromatid exchange, chromosome aberration, neutral red cytotoxicity assays in ChO cells, and the ames bacterial mutagenicity assay.

Key Points:

* The study found that CSC from 1R4F and 1R5F cigarettes was positive in the ames assay, while CSC from TOB-hT was negative in all five strains.
* CSC from 1R4F and 1R5F cigarettes was positive in sister chromatid exchange (SCE), chromosome aberration (Ca) and neutral red cytotoxicity assays, while CSC from the TOB-hT cigarette yielded negative results in all the above endpoints.
* The study used 1R4F and TOB-hT cigarettes, which were assayed concurrently, while 1R5F results were generated several months earlier.
* The CSCs were evaluated at concentrations where concentration-dependent positive responses were induced by 1R4F and 1R5F.
* The ames test was conducted using Salmonella tester strains Ta98, Ta100, Ta1535, Ta1537 and Ta1538, both in the presence and absence of metabolic activation.
* The SCE and Ca assays were conducted using ChO cells grown in McCoy’s 5a culture medium supplemented with 10% foetal calf serum, L-glutamine (2 mM), penicillin (100 units/ml) and streptomycin (100 mg/ml) at 378C in an atmosphere of 5% CO 2in air.
* The neutral red cytotoxicity assay was conducted using Chinese hamster ovary (ChO)-WBL cells and cytotoxicity was evaluated by quantifying the ability of ChO cells to incorporate neutral red into the lysosome of the cells.

Main Message:
The main message of this study is that the genotoxic and cytotoxic potential of CSC from the new cigarette that primarily heats tobacco (TOB-hT) is significantly less than CSC from Kentucky reference 1R4F and 1R5F cigarettes, which are representative of cigarettes currently sold in the US. This suggests that TOB-hT cigarettes have less cyto-toxic and genotoxic potential than tobacco-burning cigarettes currently sold in the US.

Bombick, B.Reed, h Murli, J.T avalos, D.W Bombick, W.T Morgan, K.P Putnam, and D.J Doolittle. “Chemical and Biological Studies of a newCigarette That Primarily heats Tobacco. Part 2. In Vitro Toxicology of Mainstreamsmoke Condensate.” Food and Chemical Toxicology 36, no. 3 (March 1998): 183–90. https://doi.org/10.1016/S0278-6915(97)00107-5.