Preformed tobacco-specific nitrosamines in tobacco--role of nitrate and influence of tobacco type.

Fifty-five types of commercial cigarettes on the open market in the FRG and several samples of pure tobacco types were analyzed for preformed tobacco-specific nitrosamines (TSNA) and nitrate in the tobacco. For the cigarette tobaccos the observed range for N'-nitrosonornicotine (NNN) was 50-5316 ng/cigarette and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) from not detected (less than 50 ng/cigarette) to 1120 ng/cigarette. Nitrate levels ranged from 0.6 to 14.4 mg/cigarette. The highest TSNA values were obtained for cigarettes made of dark tobaccos and the lowest for Oriental type cigarettes. The results demonstrated that there is a correlation between TSNA and nitrate levels. The tobacco type is another important influencing factor, especially for NNK. In Virginia tobaccos unexpectedly high NNK values were observed. For the samples of the pure tobacco types, NNN levels ranged from 20 to 8850 p.p.b. and NNK levels from not detected (less than 50 p.p.b.) to 1400 p.p.b. The observed range for nitrate was from traces (less than 0.005%) to 4.1%. Pure Oriental tobaccos which are low in nitrate showed the lowest TSNA concentrations. In the high nitrate Burley tobaccos the highest TSNA concentrations could be determined. Virginia tobaccos which show a low nitrate content are low in NNN but rather high NNK concentrations were found. The results from these pure tobacco types demonstrate that the nitrate content of the tobacco has a great influence on the TSNA level. However, Virginia tobaccos show higher NNK concentrations than expected according to their low nitrate content.