Health effects of electronic cigarettes

However, health effects are a function of inhaled materials, of associated behavior changes (notably traditional cigarette smoking), of how and how often the products are used, over what period, manufacturing/distribution quality control, marketing, the regulatory environment, and the actual user population.

[48] TSNAs N-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N-nitrosoanabasine, and nitrosoanatabine were detected in five e-liquid samples from two companies at levels comparable to other nicotine replacement products.

[51] The FDA warned several e-cigarette companies for selling e-cartridges and refill solutions containing active pharmaceutical ingredients such as rimonabant (Zimulti) for weight loss purposes and reducing smoking, and tadalafil (for erictile dysfunction).

The pocket may have sufficient moisture to start a chemical reaction within the lithium-ion battery, while the presence of metal objects can create a short-circuit, leading to an explosion.

[100]: Summary, 7  A 2017 review concluded "Exposure to nicotine that was specifically generated by the use of e-cigarettes, was shown to promote oxidative stress and impairment of autophagy, which in turn serves as a potential mechanism leading to development of chronic obstructive pulmonary disease.

[14] A 2017 study reported that vapor containing particulate matter with a diameter of 2.5 μm enters the circulation via the cardiopulmonary system, with a large deposit in the respiratory tract.

E-cigarette and traditional cigarette smoking in individuals with no known cardiovascular disease exhibit similar inhibition of artery dilation in response to the need for more blood flow.

[163] A 2022 study reported that common GI health effects include nausea, vomiting, gastrointestinal discomfort, xerostomia, oral mucositis, gum bleeding, gingivitis, gastric burning, altered bowel habits, and acid reflux.

Vaping is linked to impairment of cognitive processes, increased mood disorders and addiction, damage to functions such as memory, reasoning, impulse control, and attention.

[165] A 202 study reported lower gene expression, reducing occludin, which compromises the stability and strength of the blood-brain-barrier, resulting in neurovascular dysfunction, neuroinflammation, and cognitive defects.

[168]j A 2017 review concluded that nicotine and flavorings may damage periodontal ligaments, stem cells, and gingival fibroblasts in cultures from aldehydes and/or carbonyls from vapor.

[175] : 84 [93] Exhaled vapor consists of mixtures of nicotine, ultrafine particles, primarily propylene glycol, glycerin, flavorings, and aroma transporters,[11] aldehydes,[93] and volatile organic chemicals (VOC)[158] that form a visible fog.

[178] A third reported that vapor may include propylene glycol aerosols at levels that can cause eye and respiratory irritation and exceed California Environmental Protection Agency standards.

A 2017 review concluded that the few studies that examined the effect of indoor air quality on human test subjects in natural settings produced inconsistent results.

The International Union Against Tuberculosis and Lung Disease stated, "Adverse health effects for exposed third parties (second-hand exposure) cannot be excluded because the use of e-cigarettes leads to emission of fine and ultrafine inhalable liquid particles, nicotine and cancer-causing substances into indoor air.

[188] A 2014 WHO report stated passive exposure was a concern, indicating that current evidence is insufficient to determine whether the levels of exhaled vapor are safe to involuntarily exposed bystanders.

Exposure studies suggest that indoor vaping is higher than the smoke-free level put forth by the US Surgeon General and the WHO Framework Convention on Tobacco Control.

In a 15 March 2016, letter to the editor of the Journal of the American Veterinary Medical Association, the Texas Poison Center Network[208] reported 11 cases of dog exposures to e-cigarettes or refills.

[179] A 2016 review concluded, "impurities and nicotine degradation products such as nicotine-cis-N-oxide, nicotine-trans-N-oxide, myosmine, anabasine, and anatabine, which are very carcinogenic, can be reported in e-cigarette refill liquids.

[87] Nicotine promotes endothelial cell migration, proliferation, survival, tube formation, and nitric oxide (NO) production in vitro, mimicking the effect of other angiogenic growth factors.

[219] The Chk2 decrease suggests that nicotine may be capable of overriding DNA damage checkpoint activation, disrupting genetic surveillance, and increasing oncogenesis risks.

[229] A 2017 review concluded that acrolein induces oxidative stress and inflammation, disrupting lung endothelial cell barrier function and may lead to chronic obstructive pulmonary disease.

Common flavoring agents on that list include diacetyl, acetoin, 2,3-pentanedione (buttery), camphor and cyclohexanone (minty), benzaldehyde (cherry or almond), cinnamaldehyde (cinnamon), cresol (leathery) or medicinal (chocolate), and isoamyl acetate (banana).

[237] A 2019 study that sampled e-cigarette delivery systems reported that Juul pods were the only product to demonstrate in vitro cytotoxicity from both nicotine and flavoring chemical content, in particular ethyl maltol.

[75]: 160 Chemicals can be inadvertently produced, especially carbonyls such as formaldehyde, acetaldehyde, acrolein, and glyoxal when the nichrome wire (heating element) reaches a high enough temperature.

[98] The levels of nicotine, TSNAs, aldehydes, metals, volatile organic compounds (VOCs), flavorings, and tobacco alkaloids in e-cigarette vapors vary greatly.

[1] The yield of chemicals reported in the e-cigarette vapor varies depending on, several factors, including the e-liquid contents, puffing rate, and the battery voltage.

[1] The composition of e-liquids varies widely due to the extensive range of nicotine levels and flavoring additives used in these products, which result in a variety of chemical combinations.

[231][12][85] The American Heart Association reported in 2014 that some e-cigarette tank devices with stronger batteries achieve higher temperatures, which may raise nicotine levels.

[174] While myriad studies have been conducted, many questions remain unresolved, including impurities in e-liquids,[100]: Minor Tobacco Alkaloids, 193  effects of nicotine,[217][275] Exposure to e-cigarette components in a susceptible time period of brain development could induce persistent behavioral changes.

Photo of device
A first-generation e-cigarette that resembles a tobacco cigarette, with a battery portion that can be disconnected and recharged using the USB power charger
Photo of devices
Various types of e-cigarettes from 2015, including a disposable e-cigarette, a rechargeable e-cigarette, a medium-size tank device, large-size tank devices, an e-cigar, and an e-pipe
Various bottles of e-liquid.
Various bottles of e-liquid
An empty 510 thread cartridge which can be filled with liquid solution and used with compatible vape batteries
Serious adverse effects of vaping include corneoscleral lacerations or ocular burns or death after e-cigarette explosion. Less serious adverse effects of vaping include eye irritation, blurry vision, dizziness, headache, throat irritation, coughing, increased airway resistance, chest pain, increased blood pressure, increased heart rate, nausea, vomiting, and abdominal pain.
JUUL e-cigarette with a battery and differently flavored pods
Graphic from an October 2014 United States Fire Administration (USFA) report entitled Electronic Cigarette Fires and Explosions. The USFA said that 25 fires and explosions in the US were the result of e-cigarette use between 2009 and August 2014.
Graphic from an October 2014 United States Fire Administration (USFA) report entitled Electronic Cigarette Fires and Explosions . [ 94 ] The USFA said that 25 fires and explosions in the US were the result of vaping between 2009 and August 2014. [ 94 ]
Graphic from a July 2016 United States Fire Administration (USFA) report entitled Electronic Cigarette Fires and Explosions in the United States 2009 – 2016. There has been an increase in the number of severe and moderate injuries resulting from e-cigarette explosions and fires since 2014. The USFA noted that this appears to correlate well with the e-cigarette sales trend.
Graphic from a July 2016 United States Fire Administration (USFA) report entitled Electronic Cigarette Fires and Explosions in the United States 2009 – 2016 . [ 107 ] There has been an increase in the number of severe and moderate injuries resulting from e-cigarette explosions and fires since 2014. [ 107 ] The USFA noted that this appears to correlate well with the e-cigarette sales trend. [ 107 ]
E-cigarette device explodes in man's pocket while on bus in California. [ 108 ]
An image of a skin burn to the medial right thigh above the knee of a 35-year-old male.
A 35-year-old otherwise healthy male sustained a 2% total body surface area burn to his right lateral thigh when an e-cigarette device in the right back pocket of his pants spontaneously combusted, burning a hole through his pants. [ 109 ]
The most common adverse effects in e-cigarette calls to US poison control centers: Ingestion exposure resulted in vomiting, nausea, drowsy, tachycardia, or agitation. Inhalation/nasal exposure resulted in nausea, vomiting, dizziness, agitation, or headache. Ocular exposure resulted in eye irritation or pain, red eye or conjunctivitis, blurred vision, headache, or corneal abrasion. Multiple routes of exposure resulted in eye irritation or pain, vomiting, red eye or conjunctivitis, nausea, or cough. Dermal exposure resulted in nausea, dizziness, vomiting, headache, or tachycardia.
Symptoms of nicotine poisoning related to e-cigarette calls to US poison control centers [ 111 ]
Poison control center calls in the US related to e-cigarettes was one call per month in September 2010 to 215 calls per month in February 2014.
Poison control center calls in the US related to e-cigarettes was one call per month in September 2010 to 215 calls per month in February 2014. [ 124 ]
Map of reported hospitalized cases or deaths in the US and US territories. [ 145 ]
Aerosol (vapor) exhaled by an e-cigarette user may expose non-users to second-hand vapor.
Aerosol ( vapor ) exhaled by an vaper may expose non-users to second-hand vapor. [ 183 ]
A no smoking or vaping sign from the US
A no smoking or vaping sign from the US
Endogenous formation of tobacco-specific nitrosamines (TSNAs) may occur after absorption of nicotine.
Endogenous formation of tobacco-specific nitrosamines (TSNAs) may occur after absorption of nicotine . [ 219 ]
Chart showing various toxicants as measured in cigarette smoke and e-cigarette aerosol.
Chart showing various toxicants as measured in cigarette smoke and e-cigarette aerosol [ 225 ]
An image of the propylene glycol molecule
The propylene glycol molecule
The ingredients in an e-cigarette cartridge: Distilled water, Nicotine, FCC Grade Vegetable Glycerin, Natural Flavors, Artificial Flavors, Citric Acid. Nicotine content 6–8 mg per cartridge.
The ingredients in an e-cigarette cartridge: Distilled water, Nicotine, FCC Grade Vegetable Glycerin, Natural Flavors, Artificial Flavors, Citric Acid. Nicotine content 6-8 mg per cartridge.
Possible side effects of nicotine [ 246 ]
An image of the human brain. The reinforcing effects of drugs of abuse, such as nicotine, is associated with its ability to excite the mesolimbic and dopaminergic systems. How do e-cigarettes affect the brain? The nicotine in e-liquids readily absorbs into the bloodstream when a person uses an e-cigarette. Upon entering the blood, nicotine stimulates the adrenal glands to release the hormone epinephrine (adrenaline). Epinephrine stimulates the central nervous system and increases blood pressure, breathing, and heart rate. As with most addictive substances, nicotine increases levels of a chemical messenger in the brain called dopamine, which affects parts of the brain that control reward (pleasure from natural behaviors such as eating). These feelings motivate some people to use nicotine again and again, despite possible risks to their health and well-being.
The reinforcing effects of drugs of abuse , such as nicotine , is associated with its ability to excite the mesolimbic and dopaminergic systems. [ 273 ] How do e-cigarettes affect the brain ? [ 274 ] The nicotine in e-liquids readily absorbs into the bloodstream when a person uses an e-cigarette. [ 274 ] Upon entering the blood, nicotine stimulates the adrenal glands to release the hormone epinephrine (adrenaline). [ 274 ] Epinephrine stimulates the central nervous system and increases blood pressure, breathing, and heart rate. [ 274 ] As with most addictive substances, nicotine increases levels of a chemical messenger in the brain called dopamine , which affects parts of the brain that control reward (pleasure from natural behaviors such as eating). [ 274 ] These feelings motivate some people to use nicotine again and again, despite possible risks to their health and well-being. [ 274 ]
Food and Drug Administration Commissioner Scott Gottlieb announced on 28 July 2017 a comprehensive regulatory plan for tobacco and nicotine regulation that will serve as a multi-year roadmap to better protect youth and significantly reduce tobacco-related disease and death, including pursuing lowering nicotine in regular cigarettes to a minimally or non-addictive level. [ 276 ]