Electronic Cigarettes

Electronic cigarettes (e-cigarettes) are electronic nicotine delivery systems. They were patented in the United States in 2005. Although they do not contain tobacco, they are considered tobacco products by the FDA and the CDC. The FDA has authorized commercial sale of 10 e-cigarette devices and 13 tobacco-flavored e-liquids. The process of inhaling nicotine vapor into the lungs is referred to as vaping. 

The popularity of e-cigarettes has the potential to reverse the gains achieved in the public campaign against smoking. E-cigarettes are the most commonly used tobacco product among middle and high school students. In 2023, 10% of high school students and 4.6% of middle-school students reported current e-cigarette use. More than half of youth who vape nicotine also vape cannabis. Among US individuals aged 18 years or older,  4.5% use e-cigarettes, 11.5% smoke cigarettes, and many use both products. 

E-cigarettes have many different names including vapes, vape pens, vape sticks, e-hookahs, hookah sticks, mods, and personal vaporizers. They are designed to resemble USB flash drives, pens, highlighters, or toys. They may contain flavorings such as candy, fruit, mint, and menthol. E-cigarettes may be disposable or refillable. Some e-cigarettes can be used to deliver cannabis and other drugs. 

Most e-cigarettes are airflow-activated, battery powered atomizers. Inhaling on the mouthpiece activates an airflow sensor, which triggers a battery powered atomizer to heat a liquid solution (e-liquid) to approximately 55 °C and produce a vapor containing micro-droplets of nicotine. Most e-liquids contain 5% nicotine, propylene glycol, glycerin, flavorings, aldehyde carcinogens, heavy metals (nickel, tin, and lead), and diacetyl. Newer disposable devices have been engineered to deliver higher, more addictive, doses of nicotine. They contain a 10-mL well of 5% nicotine (500-600 mg) and deliver the nicotine equivalent of more than 10 packs of cigarettes. The addition of flavorings increases their appeal to youth and reduce perception of harm. 

Many people have decided to vape instead of smoke tobacco because they perceive vaping to be healthier, cleaner, and cheaper than smoking. In addition, e-cigarettes circumvent smoke-free policies in many workplaces. Because many vaping devices can be easily concealed, youth can used them in classrooms and other supervised settings. 

No tobacco products, including e-cigarettes are safe. The use of e-cigarettes causes acute physiological effects such as increased heart rate and blood pressure and airway obstruction. Adolescent vaping increases impulsivity and impaired attention. Higher doses of nicotine are associated with increased suicidal thoughts, depression, anxiety, inattention, and hyperactivity. E-cigarette use during pregnancy is associated with preterm and low-birth weight infants. Fetal lung and brain development may be affected.

E-liquid is aerosolized into ultra-fine particles that have been associated with hypersensitvity pneumonitis. A 2024 meta-analysis of 107 studies reported that nicotine vaping was associated with increased prevalence of asthma, chronic obstructive pulmonary disease, periodontitis, cardiovascular disease, and stroke.

Diacetyl has been associated with serious lung disease. It releases formaldehyde, which is a carcinogen. Vaping  3 mL of e-cigarette solution per day produces more than twice the amount of formaldehyde generated by smoking 20 tobacco cigarettes. 

Children can develop nicotine poisoning after being accidentally exposed to nicotine e-liquids. The majority of cases reported to poison control centers involve children less than 6-years old. They may be exposed by swallowing, breathing, or absorbing e-liquid through their skin and eyes. The problem has been compounded by the increased availability of vaping devices in the home due to use by guardians or older siblings. In the last 5-years, the manufacture of e-cigarette devices in the shape of toys, cartoons, or foods has exacerbated the problem. 

A major public health concern is passive exposure to e-cigarette aerosol. Air exhaled by e-cigarette users contains a comparable amount of the nicotine metabolite cotinine as air exhaled by tobacco smokers. 

Accurate testing for smoking status has become an important component in determining life insurance premiums and monitoring compliance with employment no-smoking policies. The advent of e-cigarettes has created a significant problem with interpretation of tests measuring nicotine metabolites. Traditionally, laboratory tests have relied on the presence of the tobacco-specific alkaloid anabasine to distinguish active tobacco users from those using nicotine replacement therapies. A urine sample that is positive for nicotine and its metabolite cotinine but negative for anabasine is consistent with use of nicotine replacement therapy, whereas a sample that is also positive for anabasine is consistent with tobacco use. Since some e-cigarette refills contain anabasine, users may test positive and be incorrectly identified as tobacco smokers.

References

Malani PN and Walter KL. What are -E-Cigarettes? JAMA 2024;332:768.

Piper ME, Stein JH, and Lasser KE, E-Cigarette use in Adults, JAMA 2024;332:751-52.

Winickoff JP, Evins E, and Levy S. Vaping in Youth. JAMA 2024;332:749-750.

Glantz SA et al. Population-based disease odds for e-cigarettes and sual use versus cigarettes. NEJM Evidence. 2024;3:a2300229. 

Rudasingwa G, Kim Y, Lee C, Lee J, Kim S, Kim S. Comparison of nicotine dependence and biomarker levels among traditional cigarette, heat-not-burn cigarette, and liquid e-cigarette users: Results from the Think Study. Int J Environ Res Public Health. 2021;18(9):4777.