Clearing the smoke: the science base for tobacco harm reduction—executive summary

Tobacco smoke is the cause of the most deadly epidemic of modern times.

Smoking causes cancer (for example, lung, oral cavity, oesophagus, larynx, pancreas, bladder, kidney), chronic obstructive pulmonary disease (COPD), myocardial infarction, and stroke.

The continuing toll of tobacco use has prompted the search for means of harm reduction for those who cannot or will not stop using tobacco. Numerous products that make implied or explicit claims to reduce the burden of smoking while allowing continued nicotine consumption are now entering the market. This report is concerned with the evaluation of these products.

Nearly one quarter of adult Americans—an estimated 47 million people—smoke cigarettes.1 Although this is far lower than the 42% recorded in 1965, the decline in the rates of smoking among adults appears to have levelled off during much of the 1990s.2 In a recent survey, 12.8% of middle school children and 34.8% of high school students reported some form of tobacco use during the month prior to their being interviewed.3 The vast majority of smokers begin tobacco use during adolescence.4 However, 70% of smokers say they want to quit5 and 34% of smokers make an attempt to quit each year. Thus, many but not all tobacco users find it very difficult to quit and continually expose themselves to known toxic agents.

Definition of harm reduction

For the purposes of this report, a product is harm reducing if it lowers total tobacco related mortality and morbidity even though use of that product may involve continued exposure to tobacco related toxicants. Many different policy strategies may contribute to harm reduction. However, this report focuses on tobacco products that may be less harmful or on pharmaceutical preparations that may be used alone or concomitantly with decreased use of conventional tobacco. The committee does not use the term “safer cigarette” in particular, in order to avoid leaving the impression that any product currently known is “safe”. Every known tobacco containing product exposes the user to toxic agents; every pharmaceutical product can have adverse effects.

History of efforts to reduce harm from cigarettes

There have been many efforts in the past to develop less harmful cigarettes, none of which has proved to be successful. One of the first innovations with the promise of harm reduction was the development of cigarettes with filters. Filters attempt to reduce the amount of toxicants that go into the smoke inhaled by the smoker. The next major modification of cigarettes with safety implications was “low yield” cigarettes. These products emit lower tar, carbon monoxide (CO), and nicotine than other products as measured by the Federal Trade Commission (FTC) assay (the “smoking machine”). Many consumers believed, and still do, that these products pose less risk to health than other cigarettes.

However, data on the health impact of low yield products are conflicting, in part because of a lack of systematic study early in the introduction of the products. Most current assessments of morbidity and mortality suggest that low yield products are associated with far less health benefit, if any, than would be predicted based on estimates of reduced toxic exposure using FTC yields. In order to maintain the desired intake of nicotine, many smokers who changed to low yield products also changed the way they smoked (for example, compensated by inhaling more deeply than when smoking higher yield products). Thus, their exposure to tobacco toxicants is higher than would have been predicted by standardised assays and people who have continued to use these products have not significantly reduced their disease risk by switching to them. Moreover, widespread use of these products might have increased harm to the population in the aggregate if tobacco users who might otherwise have quit did not, if former tobacco users resumed use, or if some people who would otherwise not have used tobacco did so because of perceptions that the risk with low yield products was minimal.

Types of exposure reduction products

Tobacco and cigarette-like products have been introduced recently that, under measurement systems such as the FTC smoking machine, result in decreased emission of some toxicants compared to conventional tobacco products. Currently available products include tobacco with reportedly reduced levels of some carcinogens and cigarette-like products that deliver nicotine with less combustion than cigarettes. Two classes of pharmaceutical products approved by the Food and Drug Administration (FDA) for short term use in smoking cessation might also be used for harm reduction. These include nicotine products, such as in patch, gum, inhaler, and nasal spray preparations, and a non-nicotine product that reduces the craving for tobacco. These cessation drugs could be used long term to maintain cessation or concomitantly with continued but decreased use of conventional tobacco products (table1).