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Understanding the Health Impact and Dangers of Smoke and 'Vapor'

By: Scott Gottlieb, M.D., Commissioner, and Amy Abernethy, M.D., Ph.D., Principal Deputy Commissioner 

FDA Commissioner Scott Gottlieb, M.D.
FDA Commissioner Scott Gottlieb, MD

For years, we’ve known that cigarette smoke is a major cause of death and disease, a source of many different cancers, cardiovascular and pulmonary illnesses, and numerous other serious health problems. Tobacco smoke harbors more than 7,000 chemicals, at least 70 of which are directly linked to cancer.

But it’s not just the fact that smoke is loaded with toxic chemicals that makes it so dangerous. It’s how the chemicals and particles in the cigarette smoke enter the body and the subsequent damage they cause: lung damage and disease; infections; the buildup of dangerous plaque in arteries; and blockage of blood flow to the brain, which can result in stroke, brain damage, and death. These are just some of the many dangerous health effects of cigarette smoke.

These dangers are distinct from those posed by the addictive chemical nicotine that tobacco products contain. Nicotine is especially problematic because of the impact it can have on the still-developing adolescent brain. This is why the FDA has taken significant new actions to protect youth and young adults from starting to smoke and getting addicted to nicotine and hooked on tobacco products.

That distinction — between the addictiveness of nicotine and the peril that can come from the inhaled smoke alone — is especially important as we focus new attention on health hazards posed by electronic cigarettes (or “e-cigs”) and their unique delivery systems. The popularity of e-cigarettes has skyrocketed, in part because they’re touted as safer products when compared to combustible cigarettes, because e-cigarette users inhale aerosol (often referred to as “vapor”) rather than tobacco smoke. While e-cigarettes may be less harmful than combustible cigarettes for currently addicted adult smokers who can completely switch off of combustible tobacco and onto e-cigarettes, the e-cigs are not safe There are risks associated with their use that we are still working to fully describe and quantify.

Dangers of Aerosol Exposure from E-Cigarettes

While we’re still learning about the long-term potential benefits and health risks of e-cigarettes and related products, existing scientific research offers some clear evidence that several of the dangerous chemicals in tobacco smoke are also present in the aerosol of some e-cigarette products. And this is concerning because of the very technology that distinguishes e-cigarettes — their delivery system that feeds aerosol into the body. We know that aerosol exposure is a major health concern due to the ability of aerosol particles to penetrate deeply into the respiratory system. E-cigarette aerosols can enter the lungs and small airways in various ways, which may depend on a number of factors, including nicotine content and the type of e-cigarette. That means some of the toxic chemicals and other substances contained in e-cig aerosols have the potential to go deep into the lungs and may pose risk for diseases not usually seen in smokers.

Amy Abernethy, M.D., Ph.D.
FDA Principal Deputy Commissioner, Amy Abernethy, M.D., Ph.D.

This is why we’ve been so concerned about youth use of these products. It’s not just the addiction to nicotine, and the potential for kids who become addicted to nicotine from e-cigarettes to eventually transition to regular combustible cigarettes. It’s also the direct risks posed by the e-cigarettes themselves.

This isn’t idle speculation. We know the aerosol produced by some e-cigarettes can contain high amounts of some toxic substances. Studies have shown that in addition to propylene glycol, glycerin and flavorings, e-cigarette aerosol also contains formaldehyde, acetaldehyde, and unstable atoms (free radicals) that can damage cells and cause illness and aging. Research we’ve reviewed shows substances found in e-cigarette aerosol can pose a risk for decreased lung development, breathing difficulties, lower defense against bacterial and viral pathogens, and vaping-induced inflammatory reactions that can mimic metastatic cancer.

The Unknowns of E-Cigarettes

Still, there is much we don’t know.

Most significant is the relationship between the toxicity of e-cigarette aerosol and the distinguishing characteristics of individual e-cigarette products. For example, the content and flavoring of the e-liquid can be a factor. Flavorings that are safe for use in food may become toxic when these chemicals are heated and inhaled. Some have been shown to be harmful to the lungs.

A product’s design and what it’s made from can also affect the health-related impact of e-cigarettes, including the wicking material, the nicotine content, and the device voltage and battery output.

Still another potential danger from certain types of e-cigarette designs can relate to the metal coil elements that heat and cool the product. These coils may allow traces of metal to leak into the e-liquid, resulting in metallic nanoparticles in the aerosol. As one scientific study pointed out, the FDA previously has identified nickel and chromium, which are among the metals that can enter the body through the e-cigarette delivery system, as “harmful and potentially harmful constituents,” because they are both carcinogens and respiratory toxicants.

There is one final, critical factor affecting the health impact of e-cigs, which remains an important variable — the smoking behavior of the individual user and how much he or she inhales from the e-cigarette.

Learning Through More Research

The mounting research on the physical impacts of aerosol produced by e-cigarettes provides a strong basis for concern. This is especially true when it comes to use of these products by children. But there remains a great deal to learn. This gap in knowledge and data, combined with the rapidly expanding use of these products and the potential health risks they pose, has led the FDA to embark on important new research to help characterize the toxicology of electronic nicotine delivery systems (ENDS) products.

We’re especially concerned by evidence from animal studies that the vapor in e-cigarettes can cause changes to tissue in the airways that can induce cancer or be a precursor to cancer. We have initiated a comprehensive research plan to fully evaluate these risks, and we will report our results publicly. The FDA’s Center for Tobacco Products and Center for Drug Evaluation and Research are already leading the agency’s research efforts. Four distinct types of ENDS products are being tested, each with three different flavors: a pen style device; a tank style device; a pod style device; and cigalike (one that looks like a cigarette) style. The agency will conduct toxicity studies with some or all of the four types of products and will seek to develop and provide additional information concerning the toxicity of these products. We need to fully evaluate these potential risks to inform the public as well as our own regulatory decision-making.

This new study is part of a comprehensive portfolio of research to evaluate the potential risks associated with ENDS products. We already have several studies underway — including investigations funded by the FDA — to look at the potential harmful effects of e-cigarettes on the lungs, along with other possible health risks, including those that are considered precursors to cancer.

This important, additional research will inform and support our many ongoing efforts to reduce the death and disease from tobacco products and help prevent a new generation of youth from becoming addicted to nicotine through e-cigarettes.

Regulatory Action

The FDA has made a strong commitment and taken a number of actions to address the addictiveness posed by nicotine in cigarettes. However, there are now new concerns about the dangers from aerosols inhaled by users of e-cigarettes. We see potential opportunity from the ENDS products for currently addicted adult smokers to help them quit smoking. But we also see risk, especially when it comes to youth use of these products. It’s important that we help answer difficult questions surrounding the dangers posed by aerosol from e-cigarette products. The data will help the agency as it continues to take appropriate action and advance policy steps to regulate these products.

The product application process allows the FDA to better understand the health risks of e-cigarettes. Under FDA’s enforcement discretion policy, these products have remained on the market while manufacturers prepare these applications and the FDA continues to advance foundational rules and guidance to describe an appropriate series of regulatory gates for these products. While the FDA sees potential benefit in these products being available to currently addicted adult smokers who might be able to fully transition off cigarettes, the rising prevalence of youth use is prompting us to reconsider our current enforcement discretion policy.

We will assess the potential benefits of currently addicted adult smokers fully transitioning off cigarettes and onto ENDS products while still getting access to nicotine, but potentially without the same risks as combusting tobacco. But we also must consider the risks of use by youth and others not already addicted to cigarettes. Whether it’s traditional cigarettes or e-cigarettes, the FDA will remain especially firm in preventing kids from using and becoming addicted to tobacco products.


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