Chemical composition, cytotoxicity and mutagenicity of smoke from US commercial and reference cigarettes smoked under two sets of machine smoking conditions.

Eight blended US market cigarettes, two blended reference cigarettes, one Bright tobacco only reference cigarette and an electrically heated prototype cigarette (EHC) were smoked under US Federal Trade Commission (FTC)/International Organisation for Standardisation (ISO) conditions and under Massachusetts Department of Public Health (MDPH) conditions. Smoke was analysed for chemical composition and in vitro toxicity. Yields (quantity/cigarette) of smoke constituents were higher under MDPH conditions compared to FTC/ISO conditions (market and reference average approximately 2.5 times; EHC approximately 1.6 times). Consistent with the higher yields, in vitro toxicity per cigarette was also higher under MDPH conditions. Concentrations (quantity/mg TPM) of nearly all smoke constituents measured decreased with increasing total particulate matter (TPM) yields as regression analyses indicated. Higher TPM yields also tended to be associated with slightly less cytotoxic and mutagenic activity per milligram TPM. Blended reference cigarettes tracked market cigarettes with similar TPM yield. The Bright cigarette displayed high cytotoxicity but low mutagenicity, while in vitro activity of the EHC was remarkably low. The TPM-dependent decreases for the market range of 5-20 mg TPM/cigarette were about 20%, irrespective of whether the increased yields were due to smoking conditions or cigarette construction. At the same TPM yield, the smoke constituent concentrations and in vitro toxicity were similar for low- and high-yield cigarettes.

Toxicological evaluation of an electrically heated cigarette. Part 3: Genotoxicity and cytotoxicity of mainstream smoke.

The in vitro toxicity of cigarette mainstream smoke from an electrically heated cigarette (EHC) with controlled combustion was compared with that of the standard University of Kentucky Reference Cigarette 1R4F. In the Salmonella reverse mutation assay, strains TA98, TA100, TA102, TA1535 and TA1537 were used in the absence and presence of a metabolic promutagen activation system (S9) to determine the mutagenic potential of the total particulate matter (TPM), which was collected on a glass-fiber filter. In the neutral red uptake assay, mouse embryo BALB/c 3T3 cells were used to determine the cytotoxic potential of TPM as well as of the water-solubles in the gas/vapor phase trapped in phosphate-buffered saline. The TPM from the electrically heated cigarette was up to 90% lower in mutagenicity than that of the 1R4F calculated on an equal TPM basis. This reduction in mutagenicity is consistent with the significantly lower concentration of nearly all constituents analyzed in EHC smoke. With regard to cytotoxicity when calculated on an equal TPM basis, TPM from the electrically heated cigarette was 40% less active relative to the 1R4F. When calculated on a per cigarette basis, the cytotoxicity of both the TPM fraction and the water-solubles in the gas/vapor phase of smoke from the EHC was ca. 80% lower relative to the 1R4F.

Evaluation of the potential effects of ingredients added to cigarettes. Part 3: in vitro genotoxicity and cytotoxicity.

Cigarette mainstream smoke from blended cigarettes with and without the addition of ingredients was assayed for its cytotoxicity and genotoxicity. In total, 333 ingredients commonly used in cigarette manufacturing were assigned to three different groups. Each group of ingredients was added at a low and a high level to the test cigarettes. The mutagenicity of the particulate phase of the resulting cigarette smoke was assayed in the Salmonella plate incorporation (Ames) assay with tester strains TA98, TA100, TA102, TA1535 and TA1537. The cytotoxicity of the gas/vapor phase and the particulate phase was determined in the neutral red uptake assay with mouse embryo BALB/c 3T3 cells. Within the sensitivity and specificity of the test systems, the in vitro mutagenicity and cytotoxicity of the cigarette smoke were not increased by the addition of the ingredients.