Thursday, April 15, 2010
Three Decades of Smokeless Tobacco Misinformation
On Wednesday April 14, the U.S. House Subcommittee on Health had a “kangaroo-court” hearing on smokeless tobacco. Announced only a week earlier, it was clearly a reaction by anti-tobacco extremists to an April 4th “60 Minutes” story about Sweden’s successful tobacco harm reduction efforts (watch it here).
The hearing was a diatribe against smokeless tobacco. Organizers invited only strident anti-tobacco crusaders to testify. One notable witness was Deborah Winn, a National Cancer Institute epidemiologist who fueled the misinformation campaign against smokeless tobacco almost 30 years ago.
Winn was the first author of an epidemiologic study concluding that “exceptionally high mortality from [oral cancer] among white women in the South is primarily related to chronic use of snuff. The relative risk associated with snuff dipping among white nonsmokers was 4.2.” The study, published in the New England Journal of Medicine in 1981 (abstract here), irresponsibly led the public and the medical establishment to falsely believe that smokeless tobacco was responsible for an American oral cancer epidemic.
First, Winn exaggerated her own findings. She claimed that smokeless tobacco produced an “exceptionally high mortality from [oral cancer],” even though her risk estimate only resulted in approximately 12 deaths per year among 100,000 long-term smokeless tobacco users. That mortality rate is not trivial, but it is not “exceptionally high.” It is comparable to the annual death rate of 12 to 15 per 100,000 users of automobiles – a figure that does not deter American drivers.
Exaggeration is unacceptable, but Winn’s study has a special place in the annals of American smokeless tobacco misinformation. It focused solely on a niche tobacco product -- powdered dry snuff -- used by a tiny number of women in the southern U.S. But this passage in Winn’s article transferred dry snuff’s risk to all smokeless products: “The carcinogenic hazard of oral snuff is of special concern in view of the recent upswing in consumption of smokeless tobacco in the United States.” This misleading statement appeared in the Associated Press wire story carried by the nation’s media.
Winn’s results should never have applied to chewing tobacco and moist snuff, popular American smokeless products that have been used widely with significantly fewer medical consequences than powdered dry snuff. Long after her widely cited article was published, Winn acknowledged in two obscure scientific forums that her results were specific to powdered dry snuff. In 1986, Winn was asked whether the patients in her study had used “dry snuff or [moist] snuff.” She replied, “Almost exclusively dry snuff,” and then admitted that “Dry snuff is now [in 1986] a minor portion of the U.S. market.” Her late acknowledgment in a sparsely attended scientific meeting did nothing to deter tobacco prohibitionists from misapplying her mortality claims to all smokeless products.
Epidemiologist Philip Cole and I first demonstrated the significance of Winn’s omission in our meta-analysis of smokeless tobacco and oral cancer, published in 2002 (abstract here). Our conclusion was unequivocal: “The use of moist snuff and chewing tobacco imposes minimal risks for cancers of the oral cavity and other upper respiratory sites, with relative risks ranging from 0.6 to 1.7. The use of dry snuff imposes higher risks, ranging from 4 to 13.”
The impact of Winn’s sloppy epidemiology and obfuscation is hard to overestimate. It is as if the federal official investigating the Toyota Prius accelerator problem stated that all automobiles are at risk for the defect. Winn’s 1981 report effectively projected the risk from a small subset of smokeless products to the entire smokeless category.
After nearly 30 years, Winn’s misinformation should no longer be used to keep millions of American smokers from switching to vastly safer smokeless tobacco products.