Comparative assessment of toxicities of mainstream smoke from commercial cigarettes

Three cigarette types were compared using an experimental approach for quantifying selected toxicological effects of diluted fresh whole cigarette mainstream smoke in vitro. The test procedure involved automatic smoking of cigarettes according to the FTC/ISO standard, online monitoring of generated smoke aerosols with respect to particulate and gas-phase components, and direct exposure of a human type II-like lung cell line (A549) using exposure conditions relevant to human smoking. Test specimens were the K1R4F standard research cigarettes (9.2 mg tar/cigarette) and two commercial European light filter cigarettes (brand 1, brand 2) having the same tar content (7.0 mg/cigarette). As a representative of the toxicological effect of smoke, intracellular reduced glutathione was analyzed directly after exposure of cells. Results revealed statistically significant different quantitative effects with regard to glutathione depletion when comparing whole smoke and filtered smoke from all three cigarettes. ED50 values revealed a depletion of reduced glutathione by brand 1 cigarettes that was more than twice the depletion caused by brand 2 cigarettes on a per cigarette basis. Also, quantitatively different effects were found on a per particle and on a per CO concentration basis using whole or filtered smoke from the cigarettes. We conclude that the methods we employed provide sensitive and reproducible ways of detecting differences in the toxicological action of smoke from various types of cigarettes.