Mainstream cigarette smoke (MCS) is a complex mixture of more than 5000 compounds including toxicologically relevant constituents such as tobacco specific nitrosamines, polycyclic aromatic hydrocarbons, aromatic amines, carbonyls and phenolic compounds. Various in vitro and in vivo studies have indicated that MCS may also contribute to a wide variety of potentially toxic and biologically relevant responses. Meanwhile, it has also been reported that the chemical composition and in vitro biological activity of MCS varies with smoking regime and cigarette specification. Cigarette products marketed in Japan have a variety of characteristics including diverse blend types, charcoal or non-charcoal filter and a wide range of tar yields.

The aim of this study is to investigate the chemical and biological characteristics of commercial cigarettes available on the Japanese market. MCS from three reference cigarettes (Kentucky 1R5F and 3R4F, and CORESTA Monitor 6) and 15 commercially available cigarettes (tar range from 1 to 21 mg), which included a heated cigarette, were generated according to ISO and Canadian Intense smoking regimes. Generated MCS were subject to quantitative constituent analysis in accordance with those specified in the Canadian Regulations and analysed according to the in vitro assays recommended by CORESTA In Vitro Toxicity Task Force. (Ames, Micronucleus and Neutral red uptake assay).

Results revealed that the magnitude of mutagenic activity associated with total particulate matter (TPM) in the Ames assay as well as the quantity of aromatic amines in MCS (per TPM weight unit) had a wide distribution. This was in contrast to what was observed in the other assays. Blend type and tar yield with filter ventilation also had an impact on the magnitude of mutagenic response.

Notably, a drastic reduction in MCS chemical composition and associated in vitro biological activity was observed for the heated cigarette in comparison with all combusted cigarettes.