Vaping – Impact on Adolescent Health
American College of Pediatricians – November 2020
ABSTRACT
Adolescents are known to experiment with electronic cigarettes (e-cigarettes) and to vape them on a regular basis because they consider doing so to be safe. Unfortunately, vaping is far from harmless. Health risks include addiction to nicotine and other substances, the numerous attendant harms associated with those substances as well as exposure to other toxins, including formaldehyde. The most serious complication from e-cigarette use is e-cigarette vaping-associated lung injury (EVALI) which can be fatal. ACPeds urges health professionals, educators and policy makers to do all they can to educate parents and adolescents about these dangers, and to strongly discourage teen vaping.
INTRODUCTION
Electronic cigarettes are a diverse group of primarily hand-held devices that produce a heated aerosol and have a mouthpiece to facilitate inhalation. All e-cigarette devices have a chamber to hold a liquid solution and a heating element that is usually battery powered to vaporize the solution, creating an aerosol that consists of fine particles. Most often the liquid and particles contain nicotine, propylene glycol or glycerin (which facilitate aerosolization), flavorings, and small amounts of heavy metals and other substances.1 E-cigarettes range in appearance from the first generation “vape sticks” resembling regular cigarettes to fourth generation pod-based devices that have replaceable nicotine cartridges and are easily mistaken for USB drives.1,2,3 JUUL is the most popular pod-based e-cigarette among adolescents; it is so popular that “JUULing” has become a synonym for vaping.4 Second-generation e-cigarettes resemble pens and third-generation e-cigarettes are square or rectangular-shaped tank systems that are also referred to as electronic nicotine delivery systems (ENDS), e-hookahs, or “mods”.1,2,3
E-cigarettes were initially introduced in 2006 to facilitate smoking cessation. According to the CDC, e-cigarettes “have the potential to benefit adults who smoke and who are not pregnant if used as a complete substitute for regular cigarettes and other smoked tobacco products.”2 In 2009 the Family Smoking Prevention and Tobacco Control Act placed regulation of the tobacco industry under the jurisdiction of the United States Food and Drug Administration. It was not until 2016 that the FDA introduced regulations for e-cigarettes. However, because these devices may assist with smoking cessation, unrestricted advertising was permitted.5 Due to unlimited advertising, widespread availability, relative affordability and numerous flavor options, vaping e-cigarettes has become more common among adolescents than smoking regular cigarettes.5 Although research on the health effects of e-cigarettes is on-going, this paper reviews some of the substantial evidence that vaping e-cigarettes poses numerous harms and great risk to adolescents.
EPIDEMIOLOGY
Unsurprisingly, with product advertising allowed to target young audiences, adolescent use of e-cigarettes has steadily increased. Vaping fluids, for example, are sold in boxes resembling juice cartons and are available in several appealing flavors, including cinnamon, mango, and crème brulee. In addition, with its increased legalization, marijuana readily became another common addictive ingredient added to vaping fluids.5
There are several national surveys that have evaluated the use of e-cigarettes among adolescents, including three cross-sectional surveys – the National Youth Tobacco Survey (NYTS), Monitoring the Future (MTF), and the Youth Risk Behavioral Surveillance (YRBS). Additional surveys of adult and total population use are also available and capture various measures of e-cigarette use. It is important to note, however, that there was little data on e-cigarette usage available in any of these surveys prior to 2011. In addition, there are several different terms that are used for e-cigarettes so interpretation of survey data must account for this.
In 2015, the NYTS reported that 27.1% of middle and high school students had ever used e-cigarettes. The MTF survey of 2016 reported similar rates, noting that 17.5% of 8th-grade students and 33.8% of 12th graders had ‘ever used’ e-cigarettes.5 Utilizing data from the NYTS survey in 2017, the US Morbidity and Mortality Weekly Report (MMWR) presented data that 11.3% of high school students said they had used e-cigarettes in the previous 30 days, compared with 8.0% who had used combustible cigarettes, 7.7% who had used cigars and 5.8% who had used smokeless tobacco. This pattern was found to be similar for all racial and ethnic groups with the exception of black middle and high school males who were more likely to report higher rates of cigar smoking.6 A similar report in 2018, found there had been an increase in e-cigarette use among middle school and high school students, with 840,000 middle school students (7.2%) and 4.04 million high school students (27.1%) stating they were current users. This was an increase of 38.3% from the previous year for high school students and 28.6% increase for middle school students.7 These surveys demonstrate a great increase in the use of e-cigarettes among youth and also demonstrate a preference for e-cigarettes over traditional combustible cigarettes, cigars, or smokeless tobacco. Sadly, this increase abruptly changed the previous downward trend in adolescent smoking that began in 1997.8
More concerning is evidence that adolescents are initiating e-cigarette use at younger ages. In 2014, for example, 8.8% of lifetime users started at age 14 years or younger, but by 2018, 28.6% of users had done so by age 14.9 However, the Centers for Disease Control and Prevention did report some encouraging news in September of 2020. According to the 2020 National Youth Tobacco Survey, a cross-sectional, school-based, self-administered survey conducted between January 16 and March 16, 2020, 19.6% of high school students and 4.7% of middle school students reported current use of e-cigarettes. These rates were decreased from those reflected in the 2019 report when 27.5% of high school students and 10.5% of middle school students indicated that they smoked e-cigarettes.10 This decrease in rates of use might be related to raising the federal age restriction on sales as well as public health campaigns, but it should also be noted that use of disposable e-cigarettes rose significantly from the previous year.
Peer pressure and peer-to-peer education certainly contribute to the increasing use of e-cigarettes. Examining data from 22,007 middle and high school students in the 2014 U.S. National Youth Tobacco Survey, researchers found that those adolescents who attended schools with high rates of vaping were more likely to think of e-cigarettes as less harmful and less addicting than traditional cigarettes, even if they themselves did not smoke.11 Furthermore, the abstaining students were more willing to try e-cigarettes if they attended a school with high-use.
It is difficult to know how many adolescents have been using products that contain nicotine. Initially, all e-cigarettes contained some amount of nicotine (often much higher than traditional cigarettes), but e-cigarettes that only contain flavoring have since become available. In the MTF survey, nearly 2/3 of both middle school and high school students who had ever vaped stated they only vaped flavorings at their last use. Nicotine and marijuana were used more among frequent vapers. This means that not all e-cigarettes can be designated as ENDS – electronic nicotine delivery systems – making it more difficult to understand the health risks that accompany vaping. In addition, diverse and non-standardized terminology is used when discussing e-cigarette devices and their components, increasing the difficulties in research.
Pod cigarettes (JUUL)
It is important to note that JUUL products always contain nicotine at higher levels (advertised as 3 – 5%) than the majority of other e-cigarette brands that usually contain 0 – 2.4%.12 In addition, JUUL e-cigarettes’ nicotine content is in the form of a benzoate salt.13 This makes it easier to deliver higher doses of nicotine in a low pH form that is less harsh and encourages deeper inhalation.14,15 Adolescents are not always aware of this; in one study only 37% of youth and young adult users agreed with the statement that JUUL always contains nicotine.16
Significantly, adolescent users of pod cigarettes are more likely than users of other non-pod electronic cigarette types to state they vape daily and to show more signs of nicotine dependence.
In a study of 517 adolescents recruited from three outpatient offices, those who stated they had used pod-style e-cigarettes within the past week were compared to those e-cigarette users who did not utilize a pod-style device.17 In that study, adolescents using pods tended to be younger than non-pod vapers and were more likely to state they were daily users (63%) versus non-pod users (11%). The researchers also surveyed the adolescents for symptoms of nicotine dependence and found that 21.4% of pod users provided at least one positive answer versus only 7.1% of non-pod users.
Advertising
It is important to note the role that advertising has played in this increase in sales of e-cigarettes and other electronic nicotine delivery systems (ENDS). Marketing and promotion have occurred in the media, movies, video games, social media, and the Internet. Often the products are said to be healthier and safer than traditional cigarettes, although this has not been scientifically proven. One report revealed that advertising expenses increased from $6.4 million in 2011 to $18.3 million the next year.18
JUUL (JUUL Labs) was introduced and advertised to youth in 2015 and quickly became popular among adolescents because of its replaceable pod-style nicotine cartridges, the ease of concealment, as well as its attractive design. Annual sales exceeded $650 million in 2017 despite an advertising budget of only $2.1 million between 2015 and 2017 as JUUL focused on social media, including Twitter, Instagram, and YouTube.3
JUUL’s advertising is clearly effective. Using 1129 respondents to the National MyVoice Cohort of youths between 14 and 24 years of age who were recruited the last week of January 2019, researchers found that 88% of the participants were familiar with JUUL.19
HEALTH RISKS
The National Academy of Sciences reported in 2018 on the public health consequences of e-cigarettes and labeled all the data evaluated according to its level of evidence. That report, along with more recent publications, is the basis for analyzing the health risks of e-cigarettes discussed in this paper.20
Nicotine present
Evaluating the impact of nicotine from e-cigarettes is difficult and confusing because of several factors. First, not all e-cigarettes contain nicotine. In addition, those e-cigarettes that do contain nicotine have varying concentrations of nicotine, and the various devices allow differing amounts of nicotine to be inhaled.
A study in 2015 that measured nicotine in popular brands of e-liquids purchased in the United States and two other countries found that the nicotine levels in the US ranged from below detectable to 36.6 mg/ml. Of the 32 samples taken from U.S. e-liquids, 9 (28%) had measured nicotine levels that deviated from the labeled strength by more than 20%, and, in addition, three samples had trace amounts of nicotine present even though they were labeled as being free of nicotine.21
Many other factors can influence the amount of nicotine delivered to the individual, including the power of the device, the duration of the puff, the velocity or intensity of the puff, and the additional ingredients in the e-liquid that may impact how the nicotine is distributed in the lung.1
The National Academies of Sciences, Engineering, and Medicine reviewed 25 research articles that evaluated the amount of nicotine entering an individual’s bloodstream after smoking e-cigarettes and compared that to levels obtained from traditional combustible cigarettes. The authors concluded, “These studies suggest that e-cigarettes deliver lower levels of nicotine when used by e-cigarette-naïve smokers compared with levels delivered from combustible tobacco cigarettes, which is about 1 mg.”1 However, the studies performed in smokers who were experienced in the use of e-cigarettes showed their blood nicotine levels were quite similar to those obtained when using traditional cigarettes.1
A clinical study of 22 vaping adolescents presenting to the outpatient clinics of Stony Brook Children’s Hospital in New York found their median urinary cotinine concentration of 244.8 ng/ml was much higher than had been reported previously in adolescents who smoked traditional cigarettes (155.2 ng/ml).22
A study in rats exposed to aerosols from e-cigarettes, including JUUL, versus those exposed to clean air, found endothelial cell function was impaired, comparable to impairment found with traditional cigarettes.23
Researchers have also studied the cellular damage caused by the nicotine in e-cigarettes by evaluating the oxidative stress experienced as well as gene expression profiles in human bronchial epithelial cells in culture. Again, the National Academies of Sciences report stated in their conclusion, “There is substantial evidence that e-cigarette aerosols can induce acute endothelial cell dysfunction, although the long-term consequences and outcomes on these parameters with long-term exposure to e-cigarette aerosol are uncertain.”1
Thus all the health consequences accruing to users of traditional cigarettes due to nicotine will most likely also accrue to users of e-cigarettes when the e-liquid contains nicotine. These include an increased risk of cardiovascular disease, stroke, cancer, respiratory disease and potential for addiction. However, the research is not yet conclusive since e-cigarettes have been in use for a relatively short period of time.
Toxins (Organic, Inorganic and Microbial) and Metals Present
The National Academy of Sciences review of e-cigarette use identified numerous toxins present in the e-liquids and more that are generated during the vaping process. Most e-cigarettes contain propylene glycol and glycerol as solvents, as well as metals, volatile organic compounds, phenolic compounds, and aromatic hydrocarbons.1
One study detected approximately 115 volatile organic and inorganic compounds in a single puff. When the chemical profiles of the aerosolized product were compared with that of the e-liquid, the researchers found many more compounds in the aerosolized samples, particularly formaldehyde and acetaldehyde. This demonstrated that research cannot solely focus on the components of the e-liquids being used but must also investigate the end products of the vaping process.24
In addition, metals have been detected in both the e-liquids and the aerosolized particles. These metals include chromium, nickel, lead, aluminum, and iron and may be present due to leaking from the coils and other components of the devices. Forms of chromium, lead, and nickel are all known carcinogens. One study found the tank-style e-cigarettes that operate at a higher voltage and power are more likely to produce higher concentrations of the metals.25
It should also be noted that one study demonstrated the presence of endotoxin, which is part of the outer membrane of Gram-negative bacteria, as well as glucan, a fungal wall component, in many of the e-liquid products tested. Endotoxin was found in 17 of 75 products tested (23%), while glucan was found in 61 of 75 products (81%). Exposure to these microbial toxins is known to be associated with respiratory conditions such as asthma and other reduced lung function disorders.26
Marijuana Present
Marijuana is a common ingredient incorporated into e-cigarettes, and adolescent vaping of marijuana showed a significant increase in the latest Monitoring the Future Study.27 This survey of 42,531 adolescents from 396 public and private schools revealed that 3.9% of 8th graders, 12.6% of 10th graders, and 14% of 12th graders stated they had vaped marijuana in the past 30 days. This is still lower than those who reported vaping nicotine, but marijuana vaping almost doubled in one year for those in 10th and 12 grades.
There has been little research on the effect of vaping marijuana, but presumably, they would be similar to when the drug is smoked or ingested.
A study done by Johns Hopkins researchers found that for those who use marijuana infrequently, the dose received via vaping may actually be higher than when smoked traditionally, most likely due to the higher temperature reached in the e-cigarettes. Furthermore, there were significantly greater cannabis effects on cognitive and psychomotor impairment and higher blood THC concentrations when individuals inhaled set quantities of vaporized versus smoked marijuana.28
As mentioned previously, one of the difficulties researchers face when evaluating the effects of e-cigarettes is that compounds are often generated by the aerosolizing process -- compounds that were not originally found in the e-liquids prior to vaping. Terpenes, for example, are compounds that occur naturally in cannabis but some producers add additional terpenes to their e-liquids to improve flavor and smell. Researchers have hypothesized that terpenes during the aerosol process produce potentially toxic compounds.29
Effects on cardiovascular system
The adverse effects of nicotine on the cardiovascular system are well documented and include hypertension, heart attacks, and strokes. However, we are just beginning to learn the heart health consequences of e-cigarettes, including those products that do not contain nicotine. Many articles do not specifically identify whether the e-cigarettes evaluated contained nicotine and because of the recent introduction of e-cigarettes, there are no long-term studies evaluating chronic use.
In an abstract reporting on the National Health Interview Survey from years 2014, 2016, and 2017, researchers presented data from 96,467 participants with respect to myocardial infarction, hypertension, diabetes, depression/anxiety, circulatory problems, and stroke in those who used e-cigarettes, users of traditional cigarettes, and those who were nonsmokers.
E-cigarette users had a 56% increased risk for a heart attack, and even when results were adjusted for other cardiovascular risk factors, the users still were 34% more likely to have a heart attack compared with nonsmokers. In addition, they also had higher risks for circulatory problems, including blood clots, as well as a two-fold increased risk for emotional concerns such as depression and anxiety. The risk was increased regardless of the frequency of use. It is important to note that this study did not differentiate e-cigarette users whose liquid contained nicotine from those who were not exposed to nicotine.30
Researchers at the University of Pennsylvania, however, have concluded that vaping even one nicotine-free e-cigarette causes a reduction in blood flow and impaired endothelial function in the femoral artery supplying blood to the thigh and leg. Studying 31 healthy young adult nonsmokers, the researchers measured vascular reactivity in the femoral artery and in the superior sagittal sinus in the brain, as well as stiffness in the aortic arch. Not only did they find a transient reduction in blood flow, but they also found an increase in aortic pulse wave velocity, suggesting acute aortic stiffening after just the one e-cigarette. The authors hypothesize that these changes are due to oxidative stress that occurs after particles from e-cigarettes inflame the respiratory mucosa.31
Unfortunately, there is definitely controversy in the literature. An article evaluated the effects of propylene glycol and glycerol as well as nicotine on the microcirculatory system in 25 tobacco smokers. They were exposed to vaping with and without nicotine, as well as to sham vaping, and, in the absence of nicotine and flavorings, the propylene glycol and glycerin in high-temperature e-cigarette vehicles did not alter the microvascular function, nor increase oxidative stress. (These were affected, though, in the presence of nicotine.)32
One intriguing study evaluated metabolic activity in the spleen of those using traditional cigarettes, e-cigarettes or neither. The authors describe the importance of the ‘splenocardiac axis’ - “an inflammatory signaling network underlying acute cardiac ischemia, characterized by sympathetic nerve stimulation of hematopoietic tissues, such as bone marrow and spleen, which then release proinflammatory monocytes that populate atherosclerotic plaques, thereby promoting ischemic heart disease.”33
When they evaluated metabolic activity in the spleen after smoking traditional cigarettes or nicotine containing e-cigarettes, they found splenic activity was increased in traditional cigarette users more than those who used e-cigarettes, but the metabolic activity seen in e-cigarette smokers was greater than that seen in nonsmokers. The authors state, “This activation suggests a mechanism by which tobacco cigarettes, and potentially e-cigarettes, may lead to increased risk of future cardiovascular events.”
Effects on Respiratory System
Just as cigarette smoking is associated with an increased risk for wheezing, vaping is correlated with wheezing in adults. Utilizing data from more than 28,000 adults who participated in the 2014-2015 Population Assessment of Tobacco and Health (PATH) study, researchers found that those adults who self-reported using e-cigarettes were 1.7 times more likely to experience wheezing and related respiratory symptoms than were non-users.34 This increased risk was, however, lower than the risk of wheezing seen in those who smoked traditional cigarettes.
Investigating how the particles from vaporized cigarettes impact the lungs, researchers observed vaping sessions of 23 volunteers and developed a simulated vaping machine so they could collect the aerosol and measure particle size distribution. They varied the power settings and the types of e-liquids, as well as the duration of the puff. Given the particle size found, and utilizing a model of airways, the researchers determined that although the particles from e-cigarettes are smaller than those exhaled from traditional cigarettes, they have a similar deposition pattern in human airways.35
This is concerning because known cancer-causing agents are present in the vaping aerosol, chemicals such as aldehydes, including formaldehyde. Confirming that particles from e-cigarettes actually deposit on airway cells, researchers measured the concentrations of aldehydes in the breath of 12 e-cigarette users before and after vaping. Since they knew the concentration of the aldehydes in the vapor, they could then determine how much of the chemical remained in the lungs. Their findings showed that more than 90% of the toxins (formaldehyde, acetaldehyde and acrolein) remained in the airways, and in addition the concentration of aldehydes in the user’s breath after vaping showed a ten-fold increase.36
Effects on Immune System
It is well known that nicotine and smoke from traditional cigarettes contribute to an impairment of the immune system, placing the smoker at an increased susceptibility to infection. Epithelial cell responses as well as the activation of neutrophils and macrophages are suppressed, and the interferon and cytokine responses are also altered. Researchers are now finding evidence that not only do electronic cigarettes suppress the immune system, they may also cause more damage than traditional cigarettes.
In one study comparing the responses of nonsmokers, cigarette smokers, and e-cigarette users, researchers evaluated the responses of immune cells in nasal scrape biopsies and nasal lavage for changes in gene expression.37
Utilizing a specialized machine that assessed the expression of 597 immunologic-related genes, the authors reported three main findings. First smoking either traditional or e-cigarettes caused a decreased expression in many immune-related genes. All genes that were adversely affected by traditional cigarettes were also suppressed by e-cigarettes. But even more significantly, the findings showed that vaping e-cigarettes resulted in a much greater suppression than that seen with traditional cigarettes. One stated example is that 18 genes related to cytokines were suppressed in cigarette smokers versus 75 genes suppressed in those using e-cigarettes.37
The flavorings utilized in e-cigarettes are also of concern to researchers since most have not been evaluated when inhaled. One study demonstrated the effects of flavorings on monocytes. When two monocyte cell lines were exposed to flavorings (without nicotine), including the most commonly utilized ones such as cinnamaldehyde, acetoin, o-vanillin, and diacetyl, the cells were more likely to experience cell death in a dose-dependent manner. In addition, the exposed white blood cells secreted interleukin 8 (IL-8) in a dose-dependent manner that indicated a significant inflammatory response.38
The authors also noted that flavorings caused differing degrees of toxicity, but the mixing of the flavors as is often done in e-liquids caused the greatest amount of cytotoxicity.38
Effects on Inflammatory Response, Cells, and DNA
Nicotine is known to inhibit antioxidant defenses and thereby causes DNA and cell damage. To determine whether e-cigarettes caused the same degree of DNA damage, researchers, using cell cultures, found that DNA damage occurred even when e-liquids did not contain nicotine. The damage was actually similar to that seen when cells were exposed to e-liquids containing 12 or 18 mg/ml of nicotine. This seems to indicate that components other than nicotine may be responsible for the DNA damage.39
Research from the University of Minnesota demonstrated that three DNA-damaging compounds (formaldehyde, acrolein, and methylglyoxal) were found in the saliva of individuals who experienced a 15-minute vaping session. In addition four of the five e-cigarette users participating showed DNA damage to cells in their oral mucosa.40
Dental researchers are now evaluating the effect of e-cigarettes on oral mucosa and their possible relationship to increased inflammation. One study evaluating the response of gingival epithelial cells when exposed to e-cigarettes with and without flavorings found that increases in oxidative stress and DNA damage was greater when the cells were exposed to the flavorings.41
Another study, again using cell cultures, demonstrated that cinnamaldehyde, a common flavoring in e-liquids, “rapidly disrupts mitochondrial function, inhibits bioenergetics processes, (and) reduces ATP levels” which all lead to impaired ciliary function in bronchial epithelial cells.42 Interestingly in this study the addition of nicotine to the cell cultures had no increased effect on the disruption of mitochondrial function.
Propylene glycol and vegetable glycerin are used as solvent carriers for flavors and nicotine in e-cigarettes. The aerosols from these ingredients contain more than 100 volatile organic compounds, including formaldehyde and acetaldehyde, which have been noted to cause inflammatory changes in in vitro studies. A 2019 pilot study from Ohio State University randomized 30 nonsmokers to either 4 weeks of e-cigarette use or to no-use. It is important to note that the e-cigarettes contained only 50% propylene glycol and 50% vegetable glycerin – there was no nicotine and no flavorings in the e-cigarettes smoked. The volunteers underwent bronchoscopy and bronchoalveolar lavage at both the beginning of the study and after 4 weeks of product use (in the exposed group). Changes indicative of inflammation were found in the cell counts in the lavage as well as changes in interleukin 8, 13, and tumor necrosis factor levels.43
Significantly, the researchers also found a mild dose-response of these inflammatory markers to the concentrations of propylene glycol.
E-cigarette / Vaping-associated Lung Injury– EVALI
The first report by the Centers for Disease Control and Prevention of lung injury associated with vaping was released in an MMWR report that described the death of 34 patients whose lung injury was felt to be related to vaping. Termed e-cigarette/vaping-associated lung injury (EVALI), the report included 1604 cases, 70% were male, and 79% were less than 35 years of age. Patients presented with respiratory symptoms along with fever, headache, myalgias and fatigue, making differentiation from influenza difficult. There are no diagnostic tests specific for EVALI and it remains a diagnosis of exclusion. Epidemiologic evaluation at that time indicated tetrahydrocannabinol (THC) -containing products played a major role in the disease.44
A February 25, 2020, update indicated that 2,807 hospitalizations were reported from all 50 states. Sixty-eight deaths were confirmed, but the CDC also noted a gradual decline in case reports after October 2019.
In September 2019, the University of Utah reported finding lipid-laden macrophages in the bronchoalveolar lavage from six patients with EVALI. This finding is quite unusual and the authors questioned whether these cells were reacting to components found in the vaping oil.45
Since that first report, Vitamin E acetate, a common cutting ingredient used with THC, is now felt to be a contributing factor in lung injury. In one study, vitamin E acetate was found in fluid samples taken from bronchoalveolar lavage from 48 of the 51 EVALI patients but was not found in a healthy control group.46
Vitamin E is found in many foods and does not cause harm when ingested. However, when inhaled, it may cause lung damage, and so some producers of e-cigarette liquids are removing it from their products.
An early report of 13 adolescents diagnosed with confirmed or probably EVALI found 85% of patients had gastrointestinal symptoms, while 69% of patients presented with respiratory symptoms. 92% of the patients reported they had vaped marijuana, while 62% also reported vaping nicotine, and all of the patients had bilateral ground-glass opacities on chest CT scans. Eleven of 12 patients treated with glucocorticoids improved.47
A larger study utilizing data reported in 2019 to the Centers for Disease Control and Prevention reviewed 2155 hospitalized cases of EVALI in 360 adolescents (13 - 17 years), 859 young adults (18 - 24 years), and 936 adults (25 - 49 years). The adolescents were more likely to present with gastrointestinal and constitutional symptoms rather than respiratory and were more likely to have a history of asthma and attention-deficit/hyperactivity disorder. In addition, the adolescents were more likely to have obtained their THC-containing e-cigarettes from an informal source.48
Potential Impact on Pregnancy
Although this research is limited to animal models, researchers have found decreased fertility in mice exposed to nicotine containing e-cigarette vapors, due in part to delays in implantation of the embryo.49
Risk of the Device Itself
A complete analysis of each of the various components of the e-cigarette devices and their contribution to health risks is beyond the scope of this paper, but it should be noted that the devices all carry a risk of fire and explosion due to the type of battery utilized as well as the design of the heating coils. E-cigarette devices utilize both rechargeable and non-rechargeable batteries and some have portable chargeable carrying cases. Lithium batteries are commonly used because of their ability to store large amounts of energy in a small space, but these batteries do have a risk of fire and explosion. There are other mechanisms that contribute to the risk of fire, including manufacturing flaws, improper use, and use of low-quality materials.50
Secondhand and Thirdhand Aerosol Exposure
ENDS generate an aerosol that is not only inhaled by the user but is also discharged into the environment. Those standing nearby may be exposed just as they are to secondhand smoke from traditional cigarettes. However, the secondhand smoke from e-cigarettes differs in that the aerosol is emitted directly into the air and has a different composition than the materials that make up secondhand tobacco smoke.
For instance, formaldehyde and acetaldehyde concentrations are much higher in exhaled e-cigarette breaths than in pre-vaping breaths.51
When airborne nicotine is measured via salivary and urine cotinine levels in individuals, those who lived in a home with a person using an e-cigarette had levels significantly higher than controls who lived in a smoke-free home. Levels were lower, but not significantly so, in those exposed to e-cigarette vapor compared to those exposed to traditional cigarette smoke.52
It has also been noted that nicotine can be found on surfaces such as walls and floors after a user has smoked an e-cigarette, leading some to be concerned about what is now called “thirdhand” exposure.53
Accidental Ingestions
Researchers evaluated data from the National Poison Data System from January 2012 through April 2017 for exposures to liquid nicotine in children less than six years of age. There were 8269 reports, of which 92.5% were via ingestion. The majority (83.9%) of the children were less than 3 years of age. Significantly, the annual exposure rate increased 1398.2% between 2012 and 2015, but then decreased slightly in 2016, possibly due to federal child-resistant packaging laws.54
Risk of Addiction – Gateway Drug
Recent articles demonstrate that adolescents who use electronic cigarettes are more likely to also smoke traditional cigarettes. A cohort of 11th and 12th graders in Southern California was followed prospectively for approximately 16 months. Of those adolescents using e-cigarettes at the start of the survey, 40.4% were smoking traditional cigarettes when questioned a year later versus only 10.5% of those who had never smoked e-cigarettes. This meant “e-cigarette users had 6.17 times the odds of initiating cigarettes as never e-cigarette users.”55
Several studies have evaluated which electronic devices are more likely associated with an increased risk of smoking traditional cigarettes. Adolescents who participated in an online survey in Southern California between 2015 and 2016 revealed those who had used an e-cigarette in the past 30 days were more likely to have also smoked a traditional cigarette. Those who had used a modifiable e-cigarette rather than a vape pen smoked more than six times as many traditional cigarettes at follow up a year later. Interestingly, use of nicotine in the device was not associated with increased smoking of traditional cigarettes.55
Another study found that those who used a pod-based e-cigarette were more likely to report daily use (63%) compared with those using other e-cigarettes (11%). In addition, the pod users were more likely to indicate nicotine dependence (21.4%) than other e-cigarette users (7.1%) on a questionnaire.56
CONCLUSION
The use of electronic cigarettes poses significant health hazards to adolescents, including exposure to harmful ingredients such as nicotine, marijuana, formaldehyde, and numerous other toxic chemicals, as well as heavy metals and inhaled flavorings. There is robust evidence to demonstrate that the use of e-cigarettes causes injury to the cardiovascular and respiratory systems, and to the reward system of the brain. There is also significant research to document that adolescents who use e-cigarettes face an elevated risk of developing an addiction to traditional cigarettes. Given this scientific data, the ACPeds urges all health professionals, educators and policy makers to warn parents and adolescents of the health risks due to vaping. ACPeds commends policy makers for raising the legal age to purchase vaping products to 21 and encourages consideration of bans on all flavored vaping products which appeal to the underage population who continue to access them illegally.
Principal Author: Jane E. Anderson, MD, FCP
The American College of Pediatricians is a national medical association of licensed physicians and healthcare professionals who specialize in the care of infants, children, and adolescents. The mission of ACPeds is to enable all children to reach their optimal, physical and emotional health and well-being.
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