New Study Documents the Health Effects from Snus Use: Almost Zero

A detailed review of epidemiologic studies regarding snus use has just been published online by Regulatory Toxicology and Pharmacology (abstract here). Author Peter Lee, a UK epidemiologist, concludes: “Using snus is clearly much safer than smoking. While smoking substantially increases the risk of cancer and cardiovascular diseases, any increase from snus use is undemonstrated, and if it exists is probably about 1% of that from smoking.”

Dr. Lee confirms what I have been asserting since 1994: Smokeless tobacco use is 99% less hazardous than smoking, and the magnitude of risk, if it exists, is difficult to measure using modern epidemiologic methods.

Lee reviewed the evidence from over 150 studies covering many diseases. Previously, he published separate meta analyses involving smokeless tobacco use and all cancers (abstract here), dental problems (abstract here), pancreas cancer (here), oral cancer (here), and circulatory diseases (here).

The hallmark of Lee’s analytic approach is to use all of the published evidence in a systematic and unbiased manner. This is in direct contrast to anti-tobacco advocates like Dr. Paolo Boffetta, who cherry pick the data and use only numbers that confirm their pre-existing belief that smokeless tobacco causes disease. Pancreas cancer is an excellent example.

In 2008, Boffetta published a meta analysis (abstract here) in which he claimed that snus use is a risk factor for pancreas cancer. He cited two studies, one from Norway (here) and another from Sweden (here). The Norway study reported a risk increase among all snus users (Relative Risk = 1.7, Confidence Interval = 1.1 – 2.5) but not for a subset of snus users who were never smokers (RR = 0.9, CI = 0.2 – 3.1). The Swedish study reported exactly the opposite: There was virtually no risk among all snus users (RR = 0.9, CI = 0.7 – 1.2), but the subset of snus users who never smoked had an increased risk (RR = 2.0, CI = 1.2 – 3.3).

Dr. Boffetta chose only to use the elevated risks, even though they were from different groups. As Lee points out, “For pancreatic cancer, Boffetta cited only the increases for never smokers from the [Swedish] study and for the whole population from the [Norwegian] study, not mentioning the lack of increase for the whole population for the construction workers and for never smokers for the Norway cohorts.”

It is important to note Dr. Boffetta was an author of both studies; that makes his selective use of data from them even more objectionable.

Another issue raised by Lee about another Boffetta meta analysis (here) claiming that snus use is a risk factor for fatal – as opposed to non-fatal – heart attack and stroke. In a 2009 blog post, I noted that Boffetta’s claim was questionable (here): “Boffetta found that smokeless users had no significant risk for all heart attacks and strokes but had elevated risks for fatal cases. It logically follows that smokeless users probably had LOWER risks for NON-FATAL heart attacks and strokes.” Lee echoes my concern: “Anyway, an association for fatal cases but not for all cases seems unlikely unless implausibly snus protects against non-fatal cases.”

Finally, Lee reviewed epidemiologic studies to answer this question: Does snus encourage initiation of smoking or discourage quitting? His conclusion: “There is no good evidence that introducing snus in a population would encourage smoking initiation or discourage cessation.”

This is an especially important point, because RJ Reynolds has just launched a campaign encouraging smokers to switch completely to Camel Snus (article here). While apparently in full compliance with FDA tobacco regulations, the ads have enraged prohibitionists like Matt Myers, who said that Reynolds should “stop its insidious marketing of tobacco products in ways that seek to discourage smokers from quitting and keep them hooked on nicotine...The ads are trying to take advantage of people trying to end all uses of tobacco.”

Myers is wrong about many things. Most smokers are not trying to achieve abstinence, but they are interested in enjoying tobacco in a safer manner. As Dr. Lee documents, snus is a vastly safer cigarette substitute.