American Heart Association
Timothy McAuley, PhD;
David Goff, MD, PhD, FAHA;
Neal Benowitz, MD;
on behalf of the American Heart Association Advocacy Coordinating Committee, Council on Cardiovascular and Stroke Nursing, Council on Clinical Cardiology, and Council on Quality of Care and Outcomes Research
AHA Scientific Statements
tobacco smoke pollution
For decades, advocacy for tobacco control has been a priority of the American Heart Association (AHA). In partnership with major public health organizations, the association has made major strides in tobacco use prevention and cessation by prioritizing evidence-based strategies such as increasing excise taxes; passing comprehensive smoke-free air laws; facilitating US Food and Drug Administration (FDA) authority to regulate tobacco, including comprehensive tobacco cessation treatment within healthcare plans; and supporting adequate funding of comprehensive tobacco control programs in different states. These tobacco control efforts have cut in half the youth smoking rate from 1997 to 2007 and have saved >8 million lives in the past 50 years.1 However, the work is far from done and has stalled, especially for people living below the poverty line, those with mental illnesses,2 and those with low educational attainment.3 Unless current trends reverse, ≈5.6 million children alive today in the United States will die prematurely of smoking-related diseases.1 Even now, cigarette smoking kills nearly half a million Americans each year, and an additional 16 million individuals suffer from smoking-related illness, which costs the United States $289 billion dollars annually in direct medical care and other economic costs.
This statement reviews the latest science concerning one of the newest classes of products to enter the tobacco product landscape—electronic cigarettes (e cigarettes), also called electronic nicotine delivery systems (ENDS)—and provides an overview on design, operations, constituents, toxicology, safety, user profiles, public health, youth access, impact as a cessation aid, and secondhand exposure. On the basis of the current evidence, we provide policy recommendations in key areas of tobacco control such as clean indoor air laws, taxation, regulation, preventing youth access, marketing and advertising to youth, counseling for cessation, surveillance, and defining e cigarettes in state laws. The statement concludes by outlining a future research agenda to further our understanding of this emerging area of tobacco control and the impact of e cigarettes on public health.
E cigarettes or ENDS
The first concept of an electric cigarette was patented in 1965 by Herbert A Gilbert. Subsequently, an aerosolized, high-frequency e cigarette was patented in China by Mr. Hon Lik and Ruyan Technology; it entered the marketplace in 2003 and was patented internationally in 2007. Ruyan has since registered patents in >40 countries, including the United States, and has already brought patent infringement lawsuits against several e cigarette manufacturers. E cigarette design and manufacturing processes continue to evolve, and most products on the market today use a simpler, battery-powered heating element instead of the high-frequency, ultrasonic technology patented by Ruyan.
As of early 2014, there were 466 brands and 7764 unique flavors of e cigarette products. These products are now widely available online and in retail outlets in many countries across the world. In contrast to combustible products, e cigarette availability in retail outlets in the United States is currently more likely in neighborhoods with higher median household income and a lower percentage of black and Hispanic residents. E cigarette availability in retail outlets is also higher in states with weak or nonexistent laws for clean indoor air and low cigarette taxes.12
Although the sale of e cigarettes is prohibited in some countries (Australia, Brazil, Canada, Mexico, Panama, Singapore, and Switzerland), it is allowed in most others, including the United States.13 The number of e cigarettes sold has increased exponentially year by year. Wells Fargo has predicted that sales margins for e cigarettes could grow to $10 billion by 2017, surpassing conventional cigarette sales margins. The big 3 major tobacco companies have been purchasing independent e cigarette companies and may share 75% of the profit pool in 10 years.
E cigarettes are battery-powered devices that have cartridges or refillable tanks containing a liquid mixture composed primarily of propylene glycol and/or glycerol and nicotine, as well as flavorings and other chemicals.5 During use, inhalation activates a pressure-sensitive circuit that heats the atomizer and turns the liquid into an aerosol that is inhaled by the user through the mouthpiece and exhaled as a fine mist.5 Some e cigarettes have buttons that allow the user to manually activate the heating element. The exhaled aerosol does not contain smoke, tar, or carbon monoxide. Studies of specific types of e cigarettes have shown that compared with conventional cigarettes, the byproducts from their aerosols produce very low levels of air toxins.15–17 Proponents of e cigarettes maintain that these products emulate smoking behavior without exposing the user to the toxic smoke constituents of conventional cigarettes that are deleterious to health, so there would be a public health benefit if individual smokers completely switched or substantially reduced their cigarette smoking habit.18–20 However, the use of e cigarettes could be a problem at the population level. For instance, e cigarettes could fuel and promote nicotine addiction, especially in children, and their acceptance has the potential to renormalize smoking behavior. E cigarette use could also potentially serve as a gateway to other drugs and harmful substances.
E cigarettes: Design and Operation
Since their initial manufacturing in 2003, there has been a rapid growth and evolution in the types, design, and overall engineering characteristics of e cigarettes. This has resulted in a large degree of product variability in size, potential nicotine concentrations, and e liquid formulations. There have also been changes in electrical circuitry (eg, heating element or atomizer) and battery life that allow for more e liquid delivery, adjustments in flavor, and longer device use.
Different types of e cigarettes are being developed continuously. Table 1 lists some of the different e cigarette types and name brands on the market today. Newer second- and third-generation devices allow for multiple types of user customization. This has resulted in cross-product and within-product differences in aerosol production, nicotine delivery, and product use risk. These developments significantly complicate the ability to assess the impact of e cigarettes on individual and population health.
Types of E cigarettes
Regardless of type, there are 3 basic e cigarette components: a battery, an e liquid–containing cartridge, and an atomizer (ie, a vaporization chamber with heating element).21 Other components include an airflow sensor (sensing inhalation), a microchip for controlling the heating element, and a light-emitting diode light at the tip that simulates a burning cigarette tip. All devices have air holes, which control the pressure drop and facilitate the flow of air required for puffing. E cigarettes are available with automatic or manual button–activated batteries. The battery in an automatic device is activated by inhalation or the drag, whereas manual devices require the depression of a button for battery activation. The smokelike aerosol produced by these devices is not because of the combustion of organic material; rather, it is an aerosol of the e liquid. As noted, the “atomizers” contain the heating elements that convert the fluid into an aerosol. Such atomizers are an essential component of all vaporizers, and they consist of a small heating element that evaporates the fluid and a wicking device that draws in the fluid. Since the inception of e cigarettes, the atomizers have undergone dramatic engineering changes. Developments include the evolution of the atomizer into “cartomizers” (cartridge plus atomizer), which is a combination of an e liquid distribution system and a wick/fiber and heating element.
Second- and third-generation e cigarettes models, which are larger than the first “cigarette-like” e cigarettes (cigalikes), are referred to as “clearomizers,” “tankomizers,” or “carotanks” because they can hold several milliliters of fluid in refillable reservoirs. Some second- and third-generation e cigarette batteries are available in different voltages (3.0 to 7.0 V) and with greater battery life (greater milliampere-hour) than earlier models. Within the atomizer, a resistance wire is encircled around the wicking device that draws the fluid in. When activated by the sensing device, the resistance wire rapidly heats up, turning the fluid into an aerosol, which is then inhaled by the user. The resistance and voltage applied to the heating element, as well as the material from which the heating element is made, are important determinants of the temperature achieved, which determines in part the amount and quality of the aerosol produced by the atomizer.
Some second- and third-generation e cigarettes have programmed pumps, diaphragms, or micropumps on microelectromechanical systems. These allow for a specific programmed amount or a combination of e liquid delivery to the aerosol generator.22 Some e cigarettes contain programmable logic units, integrated circuits, and other electronic components that are used to display average use cycle and safety warnings.22 Ongoing product development and evolution are likely to continue, and therefore, new regulatory policies will be important to ensure appropriate quality control.
Profile of E Cig Users
The number and duration of surveys are increasing and variably include current, former, and nonsmoker categories. These surveys are difficult to consolidate because they have been undertaken in different populations and jurisdictions, using different sampling methods and definitions, over a number of years while e cigarette types, visibility, and use have increased dramatically. Generally, non-Hispanic whites, current smokers, young adults, and those with a higher education and higher income perceive e cigarettes as less harmful than combustible tobacco products and are more likely to use them. European and North American surveys conducted in 2012 and 2013 report that most e cigarette users are current or former smokers30; 40% to 70% of all adults have heard about them, with awareness highest in smokers and growing. Such surveys also report that ≈3% to 7% of the adult population has ever used e cigarettes Among smokers in the United States and Great Britain, ≈11% report ever having used e cigarettes, whereas the use of e cigarettes is significantly lower (0.5%–1.0%) in nonsmokers. A study conducted in the Czech Republic in 2012 revealed that almost 20% of smokers who try e cigarettes go on to become regular users.
It is uncertain how many e cigarette users are smokers who really want to stop cigarette smoking or ex-smokers but persistent e cigarette users, or who want to be dual users. At present, there are few longitudinal studies to assess how many smokers are able to completely quit cigarette use, whether they continue e cigarette use after quitting or whether they continue dual use, that is, using them concurrently with combustible products. Epidemiological studies and population surveys also indicate that although many e cigarette users plan to use the devices to quit or reduce their smoking, they are usually using them in a dual-use capacity, especially in places where smoking is restricted. A survey conducted in 2012 showed that >80% of current e cigarette users do not use them on a daily basis, and almost half of all smokers indicated they may use e cigarettes in the future. Finally, among college students, another e cigarette user group, e cigarette use may not be motivated by the desire to quit smoking, nor may it lead to quitting.41In conclusion, the overall use patterns are unclear and constantly changing, which makes it difficult to draw firm conclusions about the prevalence, preference, and purpose of e cigarette use.
Concerned public health advocates see e cigarettes as a route to nicotine addiction and possibly as a potential gateway to tobacco use in youth or nonsmokers and to reinitiation of tobacco product use by former users.42 Data from the 2011 to 2012 National Youth Tobacco Survey43 showed that among students in grades 6 through 12, current e cigarette use (≥1 day in the past 30 days) increased from 1.1% in 2011 to 2.1% in 2012 and any use of e cigarettes (ever use) increased from 3.3% to 6.8% in the same corresponding years. Overall, by 2012, 1.78 million high school and middle school students nationwide had tried e cigarettes. For those students who had ever used e cigarettes, 9.3% reported never smoking conventional cigarettes, whereas 76.3% of current e cigarette users responded that they also smoke conventional cigarettes. Among never-smokers, 0.7% were currently users (past 30 days), which indicates that few never-smokers who try e cigarettes continue their use. A survey of 40 000 middle school and high school students from ≈200 schools has shown that e cigarette use is higher in current smokers and ever-smokers and among those intending to quit. This surveillance does not address whether adolescents are using e cigarettes as a gateway to smoking cigarettes, but adolescents do consider e cigarettes as high-tech, accessible, and convenient, especially in places where smoking cigarettes is not allowed. Increasingly, there is robust marketing and advertising using celebrities and appealing flavors (eg, chocolate, strawberry, and vanilla) to make e cigarettes especially more attractive and appealing to children and adolescents.45 Much of the marketing for e cigarettes has been through the Internet and social media outlets such as YouTube, but increasingly, e cigarettes are advertised on television, radio, and in the print media, where broadcast cigarette ads have been banned since 1971. Data from a US population survey indicated that for those reporting they have heard about e cigarettes, the majority (48%) reported television as their primary source, followed by “in-person conversation” and the Internet.35 Another study found that youth exposure to television advertisements for e cigarettes increased 256% between 2011 and 2013, with 24 million youth reached. Online searches for e cigarettes have surpassed those for nicotine replacement therapies (NRTs) and snus, products that have been on the market much longer.