Light smokers were defined as individuals who reported having smoked for at least one year during their lifetime and, in 1982 and 1992, reported always having smoked fewer than 5 cigarettes per day and in 1997, fewer than 10 cigarettes per day (the option of fewer than 5 cig/day was not provided on this questionnaire). Light smoking was a rare phenotype, especially among men. Among participants with DNA, 461 men and 1482 women met the criteria for light smoking. To have a total sample of light smokers the same size as the heavy smoking sample, we included all light smoking men and a random sample of 1039 light smoking women for a total of 1500 light smokers. Less than two percent of these light smokers were still actively smoking in 1997.
