Defining a never-smoker: results from the nonsmokers survey.

The U.S. Centers for Disease Control defines a never-smoker as someone who has smoked < 100 cigarettes per lifetime. In an attempt to explore differences among nonsmokers and to validate this cutpoint, we surveyed 69 nonsmokers who had smoked between 1 and 200 cigarettes in their lifetime on their experiences during the time they smoked. Of the 7 who classified themselves as ex-smokers, 2 met DSM-IV criteria for nicotine dependence, compared with none who classified themselves as never-smokers. No respondents provided data permitting the computation of a Fagerstrom Test for Nicotine Dependence (FTND) score. Withdrawal effects were minimal, but craving, tolerance, and subjective effects showed a pattern of significant differences that were most prominent between those who smoked only 1 cigarette and those who smoked at least a pack. Our data indicate a graded effect but also suggest that 19 cigarettes per lifetime is a more conservative cutpoint than 99 for defining the never-smoker phenotype. Further investigation of the smoking trajectory and characteristics associated with development of signs of dependence in never- vs. ever-smokers may help refine this cutpoint and shed light on what protects some people who experiment with smoking from becoming chronic users.