title: The linear relationship between cigarette tar and nicotine yields: regulatory implications for smoke constituent ratios.
abstract: Cigarette smoke analyte yields are often expressed as ratios relative to tar or nicotine yields, usually to compare different products or to estimate human uptake of smoke in relation to nicotine uptake measurements. The method, however, can lead to distorted interpretations, especially in the case of ratios from ultra-low tar yield cigarettes. In brief, as tar yields decrease below the 5–6 mg per cigarette range, the tar-to-nicotine ratio (TNR) decreases rapidly in a non-linear fashion. If, however, the nicotine yield, rather than the ratio, is plotted versus the tar yield, the non-linearity disappears and a straight line is obtained, with a slight positive intercept for nicotine on the ordinate. Unlike the ratio, the slope appears to depend only on the concentration of the nicotine in the blend and does not appear to vary with smoking parameters such as puff volume, puff interval or length smoked or with cigarette design parameters such as length, circumference or the amount of filtration or filter ventilation. Therefore, such a slope is analogous to the TNR although, unlike that ratio, it is invariant. Even more simply, the concentration of the nicotine in the blend, at least for American blend-style cigarettes, provides a similar index.
authors.affiliation: Consultant to British American Tobacco Investments Ltd, Group Research & Development, Southampton SO15 8TL, UK. kstcharles@bigfoot.com
authors.forename: F K
authors.initials: FK
authors.lastname: St Charles
authors.forename: C J
authors.initials: CJ
authors.lastname: Cook
authors.forename: P M
authors.initials: PM
authors.lastname: Clayton
mesh_terms: D004305:Dose-Response Relationship, Drug; D006801:Humans; D016014:Linear Models; D009538:Nicotine / Q000493:pharmacokinetics; D012907:Smoking / Q000378:metabolism; D013638:Tars / Q000493:pharmacokinetics; D019460:Tobacco Industry / Q000331:legislation & jurisprudence*; D014028:Tobacco Smoke Pollution / Q000032:analysis*; D014481:United States
chemical_list: D013638:Tars; D014028:Tobacco Smoke Pollution; C024746:tobacco tar; D009538:Nicotine