The American Heart Association has released a new scientific statement highlighting the health risks of vaping, including potential heart and lung problems, and emphasizing the need for more extensive research into long-term effects. The statement also discusses the alarming growth in e-cigarette use, especially among teenagers, and the lack of substantial evidence to support their use as a smoking cessation tool.
A new scientific statement from the American Heart Association outlines existing research on the health effects of e-cigarette use and highlights the need for further research into its long-term effects.
The American Heart Association recently published a new scientific statement in the journal Circulation, stating that research continues to reveal the health risks of e-cigarette use and further research into potential long-term effects on the heart and lungs is warranted.
This new scientific statement outlines the latest data and trends on e-cigarette use, identifies current health impacts, highlights existing basic and clinical scientific evidence related to e-cigarettes, and proposes research priorities to gain a deeper understanding of the short- and long-term health effects of e-cigarette use.
E-cigarette products, also known as electronic cigarettes, are battery-powered systems that heat a liquid solution or e-liquid to produce an aerosol that is inhaled into the lungs. Most e-liquid recipes contain nicotine, which has been shown to have negative health effects and is highly addictive. These products may also contain other substances, most commonly tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, as well as methamphetamine, methadone or vitamins. These liquids also include humectants (hygroscopic carriers such as propylene glycol and vegetable glycerin) that act as solvents and create a water mist or vapor, flavoring agents, coolants (such as menthol), and sweeteners, in addition to metals and other chemicals produced by the heating coils.
"E-cigarettes release many potentially harmful substances into the human body, including chemicals and other compounds that users may not be aware of or understand. Studies have shown that nicotine-containing e-cigarettes are associated with acute changes in several hemodynamic indicators, including increases in blood pressure and heart rate," said Jason J. Rose, MD, MBA, volunteer chair of the Scientific Statement Writing Committee, associate professor of medicine and associate dean for innovation and physician scientific development at the University of Maryland School of Medicine in Baltimore.
"There are also studies showing that even without nicotine, ingredients in e-cigarettes, especially flavorings, can pose risks related to heart and lung disease in animals. The negative effects of e-cigarettes have been confirmed through in vitro studies and studies of individuals exposed to chemicals in commercially available products."
The writing committee noted the importance of clinical diagnosis of "e-cigarette product use associated lung injury" (EVALI). In 2019, when the Centers for Disease Control and Prevention first recognized EVALI as a disease, approximately 2,800 e-cigarette users were hospitalized in less than a year. The statement cited this instance to highlight the lack of understanding about the risks of e-cigarettes and their ingredients. In hospitalized cases of EVALI, vitamin E acetate has been implicated as a possible contributor. This substance is used as a thickener in some e-cigarette liquids.
Research measuring the specific effects of e-cigarettes on heart attacks and strokes is limited. Many studies on e-cigarette use have been conducted on people who have used or currently use traditional cigarettes. Additionally, large survey studies have focused on younger adults, who have lower rates of heart attacks and strokes. The writing committee said longer-term studies are needed among e-cigarette users of all ages, including those with preexisting cardiovascular disease.
A recent analysis of the Population Assessment of Adult Tobacco and Health (PATH) study found a statistically significant association between participants who had ever or currently used e-cigarettes when joining the study and the development of respiratory disease (chronic obstructive pulmonary disease/COPD, chronic bronchitis, emphysema or asthma) within the next two years. The PATH study is an ongoing study that began in 2013 and was one of the first large-scale tobacco research efforts conducted by the National Institutes of Health and the U.S. Food and Drug Administration.
Other studies cited in the statement show that the number of people who have ever used e-cigarettes or currently use such devices has increased rapidly since 2010, with the majority of users being current or former smokers of traditional cigarettes. Additionally, by 2016, data from the Behavioral Risk Factor Surveillance System showed that approximately 1.2 million adults in the United States who had never smoked combustible cigarettes were currently using e-cigarettes.
The writing committee notes that e-cigarettes are reported to be the most commonly used tobacco product by adolescents, especially high school and middle school students. The statement cited data showing that among teenagers who use e-cigarettes, almost three out of four use flavored e-cigarette products exclusively. Such high rates of teen use make it critical to assess the short- and long-term health effects of these products, the statement said.
"Young people are often attracted to the flavors of these products and may become dependent on nicotine as a result of using e-cigarettes," Ross said. "There is great concern that young people will view e-cigarettes as harmless because e-cigarettes are widely marketed and marketed to an age group that includes many people who have never used any tobacco products. The long-term risks of using e-cigarettes are unknown. It's unknown, but if the risks of long-term e-cigarette use are the same as those of combustible cigarettes, or if the risks are reduced but still present, we may not observe them for decades. Also concerning, research shows that some teens who use e-cigarettes go on to use other tobacco products, and there is a correlation between e-cigarette use and substance use disorders."
Given the proven high health risks of smoking combustible cigarettes, e-cigarette products have been evaluated as smoking cessation tools. The writing committee examined the limited research in this area and concluded that any possible benefits of e-cigarettes in helping people quit smoking or stop using tobacco products need to be clearly balanced against the known and unknown potential health risks of the products, including the known risks of developing long-term dependence on these products.
"E-cigarette companies say their products are a way to quit traditional cigarettes. Beyond short-term benefits, there is no strong evidence to support this claim." RoseMarie Robertson, MD, deputy chief scientific and medical officer of the American Heart Association and co-director of the association's Center for Tobacco Regulatory Science, said: "The lack of long-term scientific safety data on e-cigarette use, and the potential for adolescents to become addicted to e-cigarette products, are among the reasons why the American Heart Association does not recommend the use of e-cigarettes in smoking cessation efforts."
"Equally important, e-cigarette products are not approved by the U.S. Food and Drug Administration (FDA) for smoking cessation. The association recommends that multiple sessions of cessation counseling be accompanied by personalized nicotine replacement therapy using FDA-approved dosages and formulations, as well as medications to help control cravings, to help smokers quit smoking combustible cigarettes. All of this needs to happen during the quitting process, because quitting often requires multiple attempts, and any failure should be viewed as an episode on the road to finally defeating the powerful craving for good, and lessons learned from it."
The Scientific Statement Writing Committee emphasized the urgent need for more knowledge and research, in particular:
Future research should focus on understanding the serious and potential long-term effects of e-cigarettes on the heart, blood vessels, and lungs.
Studies including patients with pre-existing heart and lung disease (such as coronary artery disease or chronic obstructive pulmonary disease) are needed to evaluate and compare the effects of treatment in e-cigarette users with traditional smokers, those who use both e-cigarettes and traditional cigarettes (referred to as dual users), and non-smokers.
More in-depth research is needed on the common chemicals in e-cigarettes and their effects on lung and heart health.
Clinical studies are also needed to examine the risks and potential benefits of e-cigarettes as an alternative to traditional combustible cigarettes.
Because the long-term health effects of e-cigarettes may take decades to manifest, more molecular and laboratory studies are needed in the meantime to help determine the biological effects of e-cigarette use.
"Because e-cigarettes and other vaping systems have only been available in the United States for about 15 years, we don't yet have enough information to understand their long-term health effects, so we must rely on short-term studies, molecular experiments, and animal studies to assess the true risks of using e-cigarettes," Jason Rose added. "It is necessary to expand this type of research because e-cigarette adoption is growing exponentially, especially among young people, many of whom may have never used combustible cigarettes."