Introduction
E-cigarettes, also known as electronic nicotine delivery systems (ENDS), vaporizers, or vape pens, are battery-operated devices that enable users to inhale an aerosolized solution. This solution typically contains nicotine, flavorings, and other chemicals. Since their introduction to the mass market around 2007, e-cigarette use, often called “vaping,” has grown exponentially among adults and youth around the world. As e-cigarette use has risen, so too has interest in investigating the potential benefits and harms of these devices through rigorous scientific research. This paper analyzes current peer-reviewed studies on the health effects of e-cigarettes, with a focus on analyzing research from credible scientific journals and medical institutions.
Chemical Composition of E-Cigarette Aerosols
One of the first considerations when evaluating the potential health impacts of e-cigarettes is analyzing their chemical composition. Several studies have identified and quantified the chemicals present in e-cigarette aerosols. For example, a 2017 analysis conducted by scientists at the University of California, Riverside tested 30 e-liquid flavors from major brands and found they contained chemicals like acetoin, diacetyl, and acetyl propionyl, which are associated with respiratory illnesses. A 2018 study published in BMC Public Health analyzed aerosol from 12 popular e-cigarette brands and found heavy metals like lead, nickel, and chromium present that could damage lungs through long-term exposure.
While nicotine is a key component of most e-liquids, some analyses have found the chemical and toxicant levels of most e-cigarette aerosols to be significantly lower than traditional cigarette smoke. A 2019 study in JAMA Internal Medicine compared the chemical makeup of e-cigarette aerosols from leading brands to combustible smoke and found e-cigarette aerosols contained fewer toxicants. E-cigarette aerosol was found to contain fewer known carcinogens and toxins associated with cardiovascular and pulmonary disease compared to conventional cigarette smoke. The long-term effects of e-cigarette aerosol chemical exposure are still largely unknown and require more research.
Health Effects of E-Cigarette Use
While the chemicals present in e-cigarettes pose risks, evaluating the overall health impacts requires examining studies on actual users. Several studies have begun to investigate the potential effects of long-term e-cigarette use. A 2020 study published in Radiology used MRI scans to examine lung damage in long-term e-cigarette users compared to non-smokers. The study found e-cigarette vapor caused abnormal lung function and reduced lung air capacity similar to traditional cigarettes. A similar 2019 study of over 32,000 American adults published in the American Journal of Preventive Medicine found that daily e-cigarette use was associated with increased odds of asthma, chronic obstructive pulmonary disease (COPD), and other respiratory illnesses, even when controlling for dual use of cigarettes.
Not all research has indicated harms. A large population-based cohort study published in 2019 in the New England Journal of Medicine evaluated U.S. military veterans and found no significant association between e-cigarette use and self-reported respiratory or heart-related events over 3 years of follow up compared to non-users after adjusting for smoking status. A 2018 study in Addiction that focused only on exclusive e-cigarette users also found no evidence of abnormalities in lung function over a 2-year period compared to non-smokers. Additional long-term prospective cohort studies are still needed as the long-term cardiopulmonary effects of e-cigarettes remain inconclusive based on currently available evidence.
E-Cigarette Use and Youth Smoking
While some consider e-cigarettes a possible reduced risk alternative to smoking, there are also concerns about increased uptake amongst youth and that vaping may act as a “gateway” to smoking for some youth. Evidence from the U.S. and other countries indicates youth e-cigarette use has grown rapidly in recent years, with some studies finding youth are more likely to try traditional cigarettes after vaping. Determining causation is difficult.
A 2020 study published in JAMA Pediatrics analyzed data from the National Youth Tobacco Survey and found current e-cigarette users were almost four times as likely to transition to cigarette smoking compared to those who never used e-cigarettes. The study was only able to show association and not prove causation. A comprehensive review published in Nicotine and Tobacco Research in 2021 analyzed 23 longitudinal studies and found limited evidence that e-cigarette use increases smoking uptake amongst youth, with most youth smokers having pre-existing risk factors that may drive them towards both vaping and smoking. Further large, prospective studies are still needed to make definitive conclusions on youth smoking risks.
Policy Considerations
As scientific evidence on e-cigarettes continues to emerge, public health organizations, governments, and policymakers face complex decisions around how best to regulate these products. While they may offer a less hazardous alternative for adult smokers seeking to quit, e-cigarettes raise concerns about youth initiation and still have unknown long-term risks that warrant further monitoring and research. Many public health experts have advocated for balanced policies involving strict regulations to limit youth access and appeal combined with maintaining e-cigarettes availability with oversight as a potentially reduced harm option for smokers seeking alternatives, although there are differing views in the medical and scientific community.
As research continues, regulatory approaches will need to account for mixed evidence and view e-cigarettes as a multifaceted issue with complex risks and benefits rather than an entirely dangerous or safe product. Balancing youth protections with harm reduction for smokers will likely involve compromise solutions like restricting youth-appealing flavors and marketing, while ensuring reasonable access to potentially lower-risk nicotine products as part of smoking cessation strategies. Overall policy decisions will require carefully evaluating an evolving body of research across disciplines like toxicology, clinical medicine, epidemiology, and youth prevention. Continued scientific inquiry into the health effects of e-cigarettes at both individual and population levels will help guide these difficult regulatory choices.
Conclusion
While short-term chemical analysis and some observational studies suggest e-cigarettes may expose users to fewer toxicants than cigarettes, long-term evidence on health effects remains inconclusive due to limitations of currently available research. There are also important public health questions about potential risks for youth uptake and addiction. At the same time, e-cigarettes could offer an alternative for some adult smokers seeking less hazardous options. Balancing these complex risks and benefits poses challenges for policy decisions in the absence of definitive scientific conclusions. Continued rigorous research across multiple scientific disciplines will be crucial to better understand the evolving public health impact of e-cigarettes and ultimately determine appropriate regulation to maximize benefits while minimizing potential harms.
Andrew Stroud