Most people are well aware that abstaining from tobacco is the only surefire way to avoid the diseases it causes. But nevertheless, almost everybody knows a "die-hard" smoker who cannot or will not quit. These people are the target for an array of new products being developed - or already on the market - that may help reduce the harm from smoking. The products include modified tobacco and cigarette-like contraptions that reportedly deliver smaller amounts of toxins. The new items - the latest in a series of attempts to lessen the harms caused by smoking tobacco - may be instilling a sense of hope in some smokers. But can they really reduce the risks and harms caused by tobacco use?

An Institute of Medicine committee that I chaired examined the scientific evidence behind these new types of modified tobacco products and their potential for reducing harm. "Harm reduction" refers to lowering total tobacco-related morbidity and mortality even though it involves continued exposure to tobacco toxicants. The committee found that although it is scientifically feasible to develop products that could reduce the risk of tobacco-related diseases, there simply hasn't been enough rigorous research to prove that they do so. In fact, it still isn't known whether they might actually threaten public and personal health by encouraging smoking. That is why it is absolutely crucial to use tried-and-true tools of public health and medicine - research, surveillance, and regulation - to assure that these products do in fact confer less risk to the individual and to the population as a whole compared with conventional tobacco products.

Attempting to reduce smokers' risks of contracting the many deadly diseases triggered by tobacco use is certainly commendable. In addition to the obvious - lung cancer - smokers are at increased risk for several other types of cancer and diseases, as well as emphysema and stroke. So the market incentive for developing these products is strong. Approximately 47 million adult Americans - about one-quarter of the adult population - still smoke cigarettes.

However, the fact is that many of the new products still contain tobacco and could cause substantial harm. For example, "light" cigarettes were advertised as having lower tar and nicotine than conventional brands. It turned out that many smokers who switched to these brands also changed the way they smoked, by smoking more or inhaling more deeply than when smoking conventional cigarettes. These behavioral changes meant that there was little or no health benefit from the introduction of "light" cigarettes. Pharmaceutical products such as nicotine gum, patches, nasal sprays, and inhalers are strictly regulated by the U.S. Food and Drug Administration for safe and effective short-term use to help people quit smoking, but have not been evaluated for long-term use in harm reduction. Indeed, more research is needed on the health effects of using these products for long periods or in tandem with smoking.

A monitoring system is essential for assessing how the introduction and marketing of modified tobacco products has affected the public's smoking behaviors and health status. The distribution, sales, and use of tobacco products, as well as their components, should be monitored. Prompt collection and reporting of these data are necessary for individuals and public health officials to decide whether these products are indeed reducing harm or whether they are detrimental to personal and public health. And at the same time, new biomedical and behavioral research is needed to show conclusively the health effects of these products.

These novel tobacco products also should be regulated more thoroughly. For example, manufacturers should base all claims on scientific evidence. That means that manufacturers should be required to conduct toxicological and clinical testing and to disclose the results. If a manufacturer makes a claim of a health benefit, its product should be subject to regulatory review to assure that it substantially reduces an individual's exposure to at least one toxicant and that, even with the remaining toxicants, it can reasonably be expected to reduce risk of a disease or other adverse health effects among users.

It is possible to make tobacco products that reduce risks, and their use in place of conventional cigarettes could reduce harm to individuals and populations. But none has been proved effective to date, and they also pose serious risks of increased harm. Only a regulatory framework can assure that these risks are known and controlled to ensure that the products do more good than harm.

If modified tobacco products are going to be an option, then public officials and consumers need to understand the consequences of using them - both positive and negative.