Levels of tobacco-specific N-nitrosamines NNN and NNK in commercial cigarettes sampled in2008-2010 – A review of analytical data
The present study was designed to determine levels of the tobacco-specific N-nitrosamines (TSNAs) N’-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in tobacco cut filler and in mainstream smoke of commercial cigarette samples.
Levels of NNN and NNK were measured in samples of 236 Philip Morris International commercial cigarette brands sold in 27 countries in 2008 and 2010 and compared to levels reported in previous surveys (Counts et al. 2004 and 2005).
The results indicate that NNN and NNK levels in tobacco cut filler of samples from 2008/2010 were on average lower by 25% for NNN and 50% for NNK than the average values reported for the same tobacco constituents by Counts et al. Smaller, but statistically significant reductions were also observed in the cigarette smoke of the same samples, using both the ISO and Health Canada Intensive machine-smoking regimens.
The observed reduction of NNN are likely due to the implementation of low converter seeds in major Burley tobacco growing areas and lower usage of fertiliser implemented as part of good agricultural practices. The reduction of NNK is likely to be attributable to the introduction of heat exchangers (barn conversion) for flue-curing of Virginia (bright) tobaccos.
 M.E. Counts, F.S. Hsu, S.W. Laffoon, R.W. Dwyer, and R.H. Cox. 2004. Mainstream smoke constitutents yields and predicting relationship from a worldwide market sample of cigarette brands: ISO smoking conditions. Regulatory Toxicology and Pharmacology 39:111-134.
 M.E. Counts, M.J. Morton, S.W. Laffoon, R.H. Cox, and P.J. Lipowicz. 2005. Smoke composition and predicting relationships for international commercial cigarettes smoked with three machine-smoking conditions. Regulatory Toxicology and Pharmacology 41:185-227.