Objectives To assess trends in smokeless tobacco use and to identify risk factors that distinguish youths who use or who are at risk of using smokeless tobacco.

Design Population based telephone surveys conducted in 1990,1992, and 1993.

Subjects Adolescent boys in California aged 12 to 17 years and men between the ages of 18 and 24. Sample sizes were 3912 in 1990, 883 in 1992, and 2814 in 1993.

Main outcome measures Current use and susceptibility to use smokeless tobacco.

Methods The predictor variables that were examined included exposure to other users of smokeless tobacco, exposure to advertisements, rebelliousness, peer norms, school performance, depression, cigarette smoking, involvement in competitive or organised sports, attending religious services, and peer use of alcohol and drugs. Age and race adjusted logistic regression analyses was used to identify important predictors of outcome measures of the 1993 data.

Results Whereas 15% of adolescent males had experimented with smokeless tobacco, current use appeared stable at around 6% for males aged 16 to 24 years. Smokeless tobacco use in teenage boys was associated with having best friends who were users (odds ratio = 13.2, p < 0.001). This effect was compounded when family members were also users (odds ratio = 34.4, p < 0.001). Recall of smokeless tobacco advertisements was also strongly associated with use (odds ratio = 7.5, p < 0.001) and susceptibility to use smokeless tobacco (odds ratio = 1.6, p < 0.001). Cigarette smokers were at greater risk of being users (odds ratio = 3.3, p < 0.001).

Conclusions Despite the large scale California Tobacco Control Program, adolescent use and susceptibility to use smokeless tobacco remained unchanged from 1990 to 1993. Exposure to other smokeless tobacco users was the largest predictor of both current use and susceptibility to use smokeless tobacco. However, peer approval and exposure to tobacco advertising were also both significant predictors for use and susceptibility. Extending the ban of tobacco marketing practices to all mass media may be necessary if smokeless tobacco use is to be reduced.