Significant Flaw in Study Claiming That Decreasing Nicotine Content of Cigarettes Reduced Smoking

Image via Shutterstock

Image via Shutterstock

Is changing the habits of the population a proper aim of government? Those who think that it is believe that there are experts or wise persons who know better what is good for people than do people themselves. Furthermore, bad habits may pass on their costs to people who do not indulge in them, which is unjust. Those who think the opposite believe that people are the best judges of their own interests, but that even if or when they are not, to allow government to interfere in this fashion is the slippery slope to totalitarianism, for there is no end to governmental paternalism’s potential claims to interfere benevolently.

Smoking is an obvious case in point. Government has sought to reduce it by a variety of means: propaganda, tax measures, restriction of circumstances in which it is legally permissible. According to a recent article in the New England Journal of Medicine, regular smokers in America reduce their life expectancy by 10 to 15 years which, if true, means that at least half the gain in life expectancy since 1960 is attributable to the decline in the percentage of the population that smokes. And if in turn this is true, it means that all the individual technical advances in medicine during that period have by comparison been trifling in their effect on life expectancy.

The same edition of the journal reports an experiment to estimate the effect of reducing the nicotine content of cigarettes on smoking behavior. It has been said that it is the tar content of cigarettes that kills people, but the nicotine content that keeps them smoking; therefore a reduction in nicotine content might result in a lesser inclination to continue to smoke, and therefore save lives by a lesser exposure to tar.

840 regular smokers who said they had no intention of giving up were recruited to the study by means of advertisements, and were offered up to $835 for their participation. Though the authors do not say so, this payment might have introduced some bias in the results, for the recruits might have lied about their intentions in order to be accepted for the study, and where a variable is unknown it cannot be controlled for.

The smokers were assigned to continue smoking their normal brand, or to smoking unmarked cigarettes of various levels of nicotine content, for a period of six weeks. The cigarettes contained 15.8, 5.2, 2.4, 1.3 or o.4 milligrams of nicotine respectively.

The results showed that at the end of 6 weeks, those who smoked cigarettes containing 2.4, 1.3, or 0.4 milligrams of nicotine smoked significantly fewer cigarettes per day than those who smoked cigarettes with 15.8 or 5.2 milligrams, and that they did not seek to compensate for lower levels of nicotine by resorting to their normal cigarettes, as the terms of the experiment permitted them to do. They did not suffer severe withdrawal effects and in fact experienced less craving for nicotine than those who had high nicotine content cigarettes. The authors concluded that regulating the permitted content of nicotine in cigarettes would be a way of reducing both adoption of and persistence in the habit.

The authors failed to notice a curious aspect of their results. The difference between the numbers of cigarettes smoked daily by the high- and low-nicotine groups was attributable not to a reduction in the number of cigarettes smoked by the latter group by comparison with their normal, pre-experiment levels, but by an increase in the number of cigarettes smoked by the former compared with their pre-experiment levels. Why this should have been the case is mysterious, but it was so.

Six weeks is a short time, even in the reduced life of a smoker. But reducing the nicotine content of cigarettes in this trial did not reduce the number of cigarettes smoked.