Wednesday, May 26, 2010

Smokeless Tobacco Use Does Not Lead to Smoking

A favorite tactic of the Campaign for Tobacco-Free Kids and other anti-tobacco extremists is the gateway allegation – “tobacco use causes _____” (fill in the blank with an undesirable behavior). For example, one of the Campaign’s pamphlets blames smoking for teenage drug and alcohol use (read it here). Extremists rarely provide rigorous proof for such claims. Given this, it is not surprising that they claim that smokeless tobacco use is a gateway to smoking.

UAB epidemiologist Philip Cole and I looked at this issue in a new study, published in Nicotine and Tobacco Research (available here). We used the National Survey on Drug Use and Health (NSDUH), which is sponsored by the federal Substance Abuse and Mental Health Services Administration.

The NSDUH asks survey participants at what age they used cigarettes or smokeless for the first time. Using this information, we classified participants as cigarette initiators (meaning they smoked before they used smokeless), smokeless tobacco initiators, or both; we then determined the prevalence of current smoking among these groups using established criteria (available here). Our analyses were restricted to white men age 18+ years (who are most likely to have used smokeless tobacco). In addition, we looked at white boys aged 16-17 years, since the gateway claim often focuses on teenagers.

Our study showed that the prevalence of current smoking among white men who were cigarette initiators was 35%. In comparison, the prevalence of smoking among smokeless tobacco initiators was only 28%, a significantly lower statistic. If the gateway effect was real, smokeless initiators would have had smoking rates similar to – or higher than – cigarette initiators.

The results for boys were even more impressive. Current smoking among cigarette initiators was 43%, but only 18% of smokeless tobacco initiators smoked. This means that boys who had started with smokeless tobacco were less than half as likely to be smoking at the time of the survey.

A few published studies have looked at the gateway issue in the U.S. In 2003, Tomar claimed that teenage boys who used smokeless were 3.5 times more likely to become smokers than nonusers of tobacco (abstract here). However, a subsequent re-analysis (available here) of Tomar’s data found that he hadn’t considered other well-known predictors of teenage smoking, such as low grades, smoking by a family member or other risky behaviors. After including these factors, smokeless tobacco use was a non-significant risk factor. Another study, by Timberlake and colleagues (available here), found “no evidence for an increased risk of smoking among the [smokeless tobacco] users.”

Anti-tobacco extremists will continue to claim that smokeless tobacco leads to smoking. However, as we conclude in our paper, our results do “not support the hypothesis that [smokeless tobacco] use is a gateway to smoking among American white males of any age, including teenagers. In fact, there is evidence that, compared with cigarette initiators, [smokeless tobacco] initiators are significantly less likely to smoke, which suggests that [smokeless tobacco] may play a protective role.”

1 comment:

Vocal EK said...

Dr. Rodu: I'd like to see you and Phillip Cole come up with an estimate of the number of deaths that could have been avoided between 1986 and now if a significant number of the 55 million smokers had switched to smokeless. That's the year that Congress began requiring the misleading warning labels. I'll bet the total potential (if all smokers had switched) numbers in the millions.