Reactions to cigarettes as a function of nicotine and "tar".

Experiments carried out to examine the effects of nicotine and "tar" on the extent of and subjective reactions to cigarette smoking. It was confirmed that smokers rate commercial, low-nicotine cigarettes as less "strong" and less "satisfying" than their usual brands. Since such cigarettes deliver reduced amounts of tar as well as of nicotine, an experiment to distinguish between the two was carried out with special cigarettes. Ratings of "strength" were directly related to nicotine but were not affected by tar. The numbers of cigarettes smoked fell slightly as their estimated delivery of nicotine increased, but tar had no effect on this index. The urinary excretion of nicotine was correlated with the rated yields of nicotine for the different cigarettes, but there was also evidence that subjects tended to adjust their manner of smoking so as to titrate their doses of nicotine. The results are interpreted as indicating a role for nicotine, but not for tar, in the maintenance of cigarette smoking behavior, and as support for the view that less harmful cigarettes should have a high yield of nicotine relative to tar.