Discussion of a Study on the “Determination of Mainstream and Sidestream Cigarette Smoke Components for Cigarettes of Different Tobacco Types and a Set of Reference Cigarettes”

The following discussion looks at some of the results of the paper by PERFETTI et al. (1) from a different perspective. Those results are in Tables 3 and 7 of PERFETTI et al. Tables in this discussion are identified by letter rather than number to avoid confusion. The main purpose of the discussion is to suggest that sidestream (SS) and mainstream (MS) yields of a smoke component should be “normalised” to SS and MS tars respectively before calculating SS/MS ratios. With the ubiquitous use of filter ventilation, simple SS/MS ratios are subject to substantial variation and may be of limited value in understanding the smoke system. BROWNE et al. (2) found that as ventilation increases (0-83 %), the SS/MS ratio for smoke nicotine increased (3.49-13.11) and PERFETTI et al. found a similar trend. This is because of the known reduction in mainstream nicotine with ventilation and the known relatively minor effect of ventilation on sidestream yields. It follows that, with the introduction of ventilation in many products, SS/MS ratios for many smoke components will have a very wide range, making this ratio of relatively little value in understanding the underlying system. However, if the SS and MS yields of component X (in this case nicotine) are “normalised” to SS and MS tar yields respectively, then a more useful ratio can be calculated. That ratio is SS yield of X per unit SS tar divided by MS yield of X per unit MS tar. In the case of nicotine/tar ratio (NTR) it is conveniently expressed as a percentage, or milligrams of nicotine per 100 mg of tar. Tables A - C use tobacco nicotine (%), weight of nicotine consumed (mg), weight of tobacco consumed (mg), MS and SS tar and nicotine (mg) from tables of PERFETTI et al. to calculate other variables and construct scatter plots. In Table A, “nicotine transfer” is the MS or SS nicotine (mg) divided by weight of nicotine consumed (mg) expressed as a percentage. “NTR” was defined previously. “TANT” (“Tar Adjusted Nicotine Transfer”) is the NTR (%) divided by tobacco nicotine (%). Table B gives the SS/MS nicotine ratios from Table 3 of PERFETTI et al. and, additionally, the SS/MS NTR ratios calculated from Table A.