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What the experience of Swedish snuff can teach us about e-cigarettes

snusA new study in JAMA Internal Medicine suggests that e-cigarettes don't help tobacco smokers quit.  This study will no doubt attract enormous attention because it relates to the hottest debate in tobacco control: Whether e-cigarettes are a boon or bane to public health. E-cigarette proponents see them as a way for cigarette smokers to transition to a less damaging way of consuming tobacco; opponents worry that e-cigarettes will entice non-smokers into using a product that will ultimately be a gateway to cigarette smoking. Until more definitive data are gathered on e-cigarettes, participants in this debate would do well to examine the experience of Swedish snuff (also known as “snus”).

Snus is a smokeless tobacco that is mainly used in Scandinavia. Its use is damaging to health, but because it is not smoked and contains a low level of cancer-causing nitrosamines, the damage to users and those around them from snus is less than that of tobacco cigarettes. The fundamental question at play in the current e-cigarette debate was also raised regarding snus: Would it be a net harm or a net benefit to public health?

A study of 15,000 Swedish males examined snus use and smoking among a younger (age 16-44) and older (age 45-84) cohort. About 18 percent of tobacco smokers had previously been snus users. This gateway effect from snus to cigarettes was more common for older than younger individuals.  However, in both cohorts, the reverse pattern was far more common, leading to an overall drop in tobacco smoking. Among the younger cohort, snus accounted for six smoking quitters for each smoking starter.  In the older cohort, the benefit was less: About two smoking quitters per starter. Given the size of these effects and the prevalence of snus use, it is entirely credible to argue that snus has contributed to the declining lung cancer rate in the Swedish population.

The Swedish results would seem to make a conclusive case for the public health benefits of snus. However, a subsequent study of 1151 Finnish men had starkly different results. Only 22 participants in the study had replaced tobacco smoking with snus use. The norm in this population was to use snus to supplement rather than replace cigarette smoking, tending to increase the physical dependence of tobacco users. Although not able to draw a definitive conclusion, the authors noted that “it is likely that snus use complicates the attempts to quit smoking”.

The science on snus is thus unsatisfying for those desiring a simple answer regarding the public health value of putatively less harmful forms of tobacco. In one context, snus was enormously beneficial. In another, it appears to have made things worse. The effect of snus also varied across historical time periods as younger and older people used it in distinct ways.

The experience of e-cigarettes may very well follow the same pattern - or perhaps it is better said - the same lack of a pattern. An empirically grounded, universally valid judgment on the impact of e-cigarettes may be difficult to attain. Whether they are a net positive or negative for public health will depend on the context in which they are used, the degree to which different generations adopt them, and the regulations society sets regarding them.

Addiction expert Keith Humphreys, PhD, is a professor of psychiatry and behavioral sciences at Stanford and a career research scientist at the Palo Alto VA. He recently completed a one-year stint as a senior advisor in the Office of National Drug Control Policy in Washington. He can be followed on Twitter at @KeithNHumphreys.

Previously: E-Cigarettes: The explosion of vaping is about to be regulated
Photo by Ole C Eid

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