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Tobacco-specific nitrosamines (TSNA) levels in tobacco cut filler and cigarette smoke were measured in more than 1000 commercially available cigarettes sampled between 2008 and 2014. Relative contributions to their transfer from tobacco to the mainstream smoke in terms of direct transfer by distillation, pyrorelease, and pyrosynthesis were evaluated on the basis of the comparison with the transfer of nicotine from tobacco to smoke. N′-nitrosonornicotine (NNN) was transferred essentially by distillation, while N′-nitrosoanatabine (NAT), 4-(methylnitrosamino)-1-(3-bipyridyl)-1-butanone (NNK) and N′-nitrosoanabasine (NAB) were transferred by pyrorelease or pyrosynthesis as well. In the case of the Tobacco Heating System 2.2, the transfer of nicotine from tobacco to the aerosol was similar to that observed for cigarettes, while the % transfer of TSNAs from tobacco to THS 2.2 aerosol was 2–3 times lower than in cigarettes. This difference is due to the fact that the tobacco is heated instead of burnt resulting in a lower direct transfer by distillation and a lower if any contribution of pyrosynthesis or pyrorelease.The transfer of TSNA from tobacco to cigarette mainstream smoke was evaluated by comparison to the transfer of nicotine.NNN transfers essentially by distillation, while NNK, NAB and NAT also transfer by pyrosynthesis and/or pyrorelease.In THS2.2, there is a factor 2 to 3 reduction in the % transfer of TSNA in comparison with cigarettes.