Health effects of electronic cigarettes
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The use of
E-cigarettes reduce lung function, reduce
There are also risks from misuse or accidents.[10] Such accidents can be through nicotine poisoning (especially among small children[11]),[12] contact with liquid nicotine,[13] and fires caused by vaporizer malfunction.[3]
Methodological issues
The long-term consequences from e-cigarette use on death and disease are unclear.[14] There is little data about safety, and considerable variation among e-cigarettes and the liquid ingredients.[15]
Alternatives to smoking
Electronic cigarettes have been proposed as a healthier alternative for people who otherwise cannot or choose not to quit smoking, even if complete abstinence is the healthiest option. In June 2014, the Royal College of Physicians stated that, "On the basis of available evidence, the RCP believes that e-cigarettes could lead to significant falls in the prevalence of smoking in the UK, prevent many deaths and episodes of serious illness, and help to reduce the social inequalities in health that tobacco smoking currently exacerbates."[17] Vapor does not contain tobacco and does not involve combustion, therefore users may avoid several harmful constituents usually found in tobacco smoke,[10] such as ash, tar, and carbon monoxide.[18] A 2014 review found that e-cigarette aerosol contains far fewer carcinogens than tobacco smoke, and concluded that e-cigarettes "impart a lower potential disease burden" than traditional cigarettes.[19] The public health community is divided over how the use of these devices will impact the tobacco epidemic.[20] Some tobacco control advocates predict that e-cigarettes will increase rates of cigarette uptake, especially among youth.[20] Others envision that these devices have potential for aiding cessation efforts, or reducing harm among people who continue to smoke.[20] Scientific studies advocate caution before designating e-cigarettes as beneficial but vapers continue to believe they are beneficial.[21] It is estimated their safety risk is similar to that of smokeless tobacco, which has about 1% of the mortality risk of traditional cigarettes.[22] The risk of early death is anticipated to be similar to that of smokeless tobacco.[23]
Public health authorities are concerned that electronic cigarettes may increase overall nicotine exposure for young people and increase use of burned tobacco products among young[25] and older people by acting as a gateway drug for non-smokers and sustaining or restarting nicotine addiction among smokers and former smokers, respectively.[26] As of 2013[update], no long-term studies have evaluated future tobacco use as a result of e-cigarette use.[27] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[28] A study conducted found that people using electronic cigerattes go through more nicotine than traditional tobacco users.[29]
Opinions that e-cigarettes are a safe substitute to traditional cigarettes may compromise tobacco control efforts.[30] The American Cancer Society stated, "The makers of e-cigarettes say that the ingredients are "safe," but this only means the ingredients have been found to be safe to eat. Inhaling a substance is not the same as swallowing it. There are questions about how safe it is to inhale some substances in the e-cigarette vapor into the lungs."[31] The Canadian Cancer Society has stated that, "A few studies have shown that there may be low levels of harmful substances in some e-cigarettes, even if they don't have nicotine."[32] In the UK a National Institute for Health and Care Excellence (NICE) guideline did not recommend e-cigarettes as there are questions regarding the safety, efficacy, and quality of these products.[33]
Because the devices are relatively new, long-term data showing whether vaping is a "healthier alternative" to cigarette smoking does not exist.[9]
Effects on increasing nicotine products
A concern regarding vaping is that it could entice children to initiate smoking. This could be the argument that nicotine leads to smoking or making smoking appear more acceptable again.[34] Concerns exist in respect to adolescence vaping due to studies indicating nicotine may potentially have harmful effects on the growing brain.[35]
The medical community is concerned that increased availability of e-cigarettes could increase worldwide
Effects on smoking cessation
There is concern that e-cigarettes may result in smokers rejecting historically effective quitting smoking methods.[19] Majority of smokers attempting to quit by vaping may stop smoking but maintain nicotine intake because their long-term effects are not clear.[42] Since e-cigarettes are intended to be used repeatedly, they can conveniently be used for an extended period of time, which may contribute to increased consumption.[43]
Frequently reported less harmful effects of vaping compared to smoking were reduced shortness of breath, reduced cough, reduced spitting, and reduced sore throat.[21] Many health benefits are associated with switching from tobacco products to e-cigarettes including decreased weight gain after smoking cessation and improved exercise tolerance.[44] Vaping is possibly harmful by virtue of putting off quitting smoking, serving as a gateway to tobacco use in never-smokers or causing a return to smoking in former smokers.[45] Many e-cigarette users cite a desire to quit smoking as a primary reason for use but there is not clear evidence that e-cigarettes help people quit smoking entirely, although they may help smokers reduce the number of cigarettes they smoke.[46] There is some evidence that the usage of electronic cigarettes with nicotine increases quit rates compared to electronic cigarettes without nicotine and compared to nicotine replacement therapy.[47] The size of the effect (i.e. how effective the electronic cigarettes are compared to the other options) is not known.[47] Some frequently use both, exposing themselves to both the harms of tobacco smoking and the possible harms of e-cigarette use.[46]
Vaping can hinder smokers from trying to quit, resulting in increased tobacco use and associated health problems.[48] Quitting smoking entirely would likely have much greater beneficial effects to overall health than vaping to decrease the number of cigarettes smoked.[3] A 2017 review found "Because the brain does not reach full maturity until the mid-20s, restricting sales of electronic cigarettes and all tobacco products to individuals aged at least 21 years and older could have positive health benefits for adolescents and young adults."[49] Adverse effects to the health of children is mostly not known.[50] E-cigarettes are a source of potential developmental toxicants.[51] Children subjected to e-cigarettes had a higher likelihood of having more than one adverse effect and those were more significant than with children subjected to traditional cigarettes.[50] Significant harmful effects were cyanosis, nausea, and coma, among others.[50]
Whether you are vaping THC, nicotine, or flavorings, those vapes produce other harmful chemicals that are inhaled into your body. [52] More serious adverse effects, such as depression, insomnia, and anxiety, are frequently related with smoking use.[53] A study was conducted which concluded that a primary reason most vape user quit is due to health (75%), cost (45%), and to reduce risk of COVID-19 (24%). Methods most users used to quit vaping were by cutting (68%), getting advice from doctors (28%), quitting 'cold turkey' (24%), nicotine, or switching to E-cigarette with less nicotine (24%).[54]
E-cigarettes were associated with fewer adverse effects than nicotine patches.[55] Contact dermatitis from nickel exposure has been reported, following e-cigarette use.[56]
Overall risk relative to smoking
The degree of relative safety of the same amount of use of electronic versus conventional cigarettes is disputed. 2015[57] and 2018 Public Health England (PHE) reports claimed that vaping is "at least 95% less harmful than smoking", while pointing out that this does not mean vaping is safe.[58] This claim has been widely repeated, including by the Royal College of Physicians, the Royal Society for Public Health, and the National Health Service.[41] The original paper making the claim pointed out that the accuracy of the estimate was limited by "lack of hard evidence for the harms of most products on most of the criteria".[41] The group that produced the estimate in a 2014 meeting was funded by EuroSwiss Health and has been criticized as using a weak methodology,[59] not citing specific evidence,[41] and for having financial ties to the tobacco industry.[59][41]
The estimate has been extensively disputed in medical journals.[60] Many have criticized the validity of the estimate that vaping is 95% less harmful than smoking.[38] Some researchers claim in more recent papers that the harm from electronic cigarettes is known to be much higher than the "95% safer" figure.[61][41]
A government review by Public Health England[62] found that e-cigarettes sold in England (which are regulated to a nicotine strength[63] of no more than 20 mg/ml[64]) are unlikely to exceed 5% of the harm of cigarettes for non-pregnant adults. This claim is consistent with the view of the National Academies of Sciences, Engineering, and Medicine[65] of the United States, which argues that e-cigarettes are not without risk, but compared to combustible tobacco cigarettes, they contain fewer toxicants. Furthermore, e-cigarette is not only a harm reduction alternative to smoking; but it is also a smoking cessation product, to the same extent of other Food and Drug Administration-approved nicotine replacement therapies.[66]
Regulation
Guidelines for the design, manufacture and assessment of the safety of e-cigarette devices has not been established.[67] A 2015 review suggested that e-cigarettes could be regulated in a similar way as inhalation therapeutic medicine, meaning they were regulated based on toxicology and safety clinical trials.[68]
A 2014 review recommended that e-cigarettes could be adequately regulated for
E-cigarette devices are not required to disclose the level of nicotine provided, nor the other chemicals they contain, being difficult for consumers to assess the safety of the product.[71]
Suction
Vaping requires more forceful sucking than smoking, and this action is still unclear on increased absorption of harmful substances and the user's health.[72] Sucking more forcefully from e-cigarette use may be adverse to human health.[73]
Adverse effects
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Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.[74] There is a small risk of battery explosion in devices modified to increase battery power.[68] Nicotine poisoning related to e-cigarettes can occur by ingestion, inhalation, or absorption via the skin or eyes.[12] Accidental poisoning can result from using undiluted concentrated nicotine when mistakenly used as prepared e-liquid.[75] There is possibility that inhalation, ingestion, or skin contact can expose people to high levels of nicotine.[70] Concerns with exposure to the e-liquids include leaks or spills and contact with contaminants in the e-liquid.[76] Pregnant women, breastfeeding mothers, and the elderly are more sensitive to nicotine than other individuals.[77] There are safety issues with the nicotine exposure from e-cigarette use, which may cause addiction and other adverse effects.[4] There is considerable variation among e-cigarettes and in their liquid ingredients[15] and thus the contents of the aerosol delivered to the user.[3] The cytotoxicity of e-liquids varies,[78] and contamination with various chemicals have been detected in the liquid.[79] E-cigarette vapor potentially contains harmful chemicals which are not found in tobacco smoke.[28]
Studies over a year on the effects of exposure to e-cigarettes have not been conducted, as of 2019.
Adverse effects are mostly associated with short-term use and the reported adverse effects decreased over time.[85] Dryness of the mouth and throat is believed to stem from the ability of both propylene glycol and glycerin to absorb water.[86] Some e-cigarettes users experience adverse effects like throat irritation which could be the result of exposure to nicotine, nicotine solvents, or toxicants in the aerosol.[12] Vaping may harm neurons and trigger tremors and spasms.[87] The use of e-cigarettes has been found associated with nose bleeding, change in bronchial gene expression, release of cytokines and proinflammatory mediators, and increase in allergic airway inflammation which can exacerbate asthmatic symptoms, thus elevating infiltration of inflammatory cells including eosinophils into airways.[37] A 2016 study found vaping using an e-liquid containing 23% alcohol was linked to reduced performance on the Purdue Pegboard Test.[88]
Reports to the FDA in 2013 for minor adverse effects identified with using e-cigarettes included headache, chest pain, nausea, and cough.[74] Major adverse events reported to the FDA in 2013 included hospitalizations for pneumonia, congestive heart failure, seizure, rapid heart rate, and burns.[74] However, no direct relationship has been proven between these events and e-cigarette use, and some may be due to existing health problems.[74] Many of the observed negative effects from e-cigarette use concerning the
Most e-cigarettes use
The numbers of medical reports from harms resulting from vaping have continued to increase since 2016.[67] Some batteries are not well designed, are made with poor quality components, or have defects.[74] Major injuries have occurred from battery explosions and fires.[3] Fires caused by e-cigarettes appear to be increasingly frequent.[90] Direct harms from an e-cigarette blast include hand harms, face harms, waist/groin harms, and inhalation harms.[90] Indirect harms happened when the vaporing device set on fire another object and resulted in a house fire, followed by harm from fire burns or inhalation.[90] E-cigarette explosions have resulted in burns, lost teeth, neck fractures, and battery acid contact to the face, mouth, and eyes.[81] The extent of the burns varied from 1% to 8% total body surface area, were reported and most commonly occurred in the lower extremity, hands, head and neck, and genitalia.[95] The extent of the burn was mainly deep partial and full thickness.[95] E-cigarette explosion harms correlated with malfunctioning of the device can result in minor total body surface area 2nd and 3rd degree burns.[99] Around 50% needed surgical management for the burn.[95] This was due to the extent of the injury.[95] The most common harms are burns as a result of explosion in the pocket and harms to the face.[90] A 2017 review found "Several of the reported cases show that 'the battery in pocket' precedes the incident. The damp environment in the pocket may have sufficient moisture to start a chemical reaction within the lithium-ion battery and the presence of metal objects can produce short-circuit which can over heat the battery leading to an explosion."[93] Flame burns, chemical burns, and blast injuries have occurred as a result of the e-cigarette battery overheating.[100] A man endured a unilateral corneoscleral laceration with prolapsed iris tissue and hyphemato to the eye area when an e-cigarette exploded in his mouth.[81] A young man endured bilateral corneal burns to the eye area when an e-cigarette exploded near his chest.[81] A man died when his charging e-cigarette blew up and caught on fire next to oxygen equipment.[81] House and car fires and skin burns have resulted from some of the explosions.[74] The explosions were the result of extended charging, use of unsuitable chargers, or design flaws.[10] There is a possible risk to bystanders from e-cigarette explosions.[81] There is also a risk of property damage as a result of flammable materials catching on fire from an e-cigarette explosion.[81] A March 2016 research article assembled reports by US government agencies and in the media of 92 e-cigarette blasts, fire, or overheating events, with related injuries in 47 individuals.[101] Prominent harms included 2 cervical vertebral fractures, 1 palate fracture, 3 instances of damaged teeth, 33 thermal burns, 4 chemical burns, and 5 lacerations.[101]
Between January 2015 and May 2016, 35 burns and correlated injuries were caused by e-cigarette explosions.[95] Between January 2009 and December 31, 2016, 195 separate incidents of explosion and fire involving an e-cigarette were reported by the US media.[98] These incidents resulted in 133 acute injuries.[98] Of these injuries, 38 (29 percent) were severe.[98] Sixty-one incidents occurred when either the device or spare batteries for the device were in a pocket.[98] Sixty incidents occurred while the device was being used.[98] Forty-eight incidents occurred while the battery in the device was being charged.[98] Eighteen incidents occurred while the device or battery was stored.[98] In seven incidents, it is not reported whether the e-cigarette was in use, stored, or being charged.[98] One incident occurred during transportation on a cargo aircraft.[98] Media reports generally characterize these incidents as explosions.[98] While there is generally a brief period of overheating and off-gassing at the onset of the event, the events tend to occur suddenly, and are accompanied by loud noise, a flash of light, smoke, flames, and often vigorous ejection of the battery and other parts.[98] A number of the media reports state that the battery or other components of the device were ejected under pressure and "flew across the room," often igniting combustible items where they landed.[98]
The United States Fire Administration stated in 2014 that 25 fires and explosions in the US were caused by e-cigarettes between 2009 and August 2014.[98] This list is not considered to be complete because it is very possible that there were events that were not disclosed to the fire department or mentioned in the media.[98] Up to 2014, twenty events happened when charging the battery in the e-cigarette.[98] Two events happened during use.[98] In two events, it is unclear whether the device was in use, not in use or was charging.[98] One event happened while being transported on a cargo aircraft.[98] Several burns were reported.[98] Two serious harms were the result of devices exploding in users' mouths.[98] A 2017 review found that "The U.S. Fire Administration reports that 80% of e-cigarette explosions occurred while the battery was being charged. The report revealed that many of the e-cigarettes were being charged by power adaptors that were not provided by the manufacturer, subjecting the battery to an inappropriately high current, which led to thermal runaway and subsequent explosion and/or fire. This problem is potentially further exacerbated by third-party vendors who assemble e-cigarettes from noncompatible parts that may not meet the manufacturers' specifications."[101] The shape of these devices is another concern.[101] They are likely to be cylindrical, with the least strongest structural points at both ends.[101] In the event there is a breach in the battery seal, the pressure inside the e-cigarette can quickly build, launching the ends of the device with a great abundance of force.[101]
The United States Fire Administration stated in 2017 that of the reported fire and explosion incidents involving e-cigarettes, 128 (66 percent) resulted in ignition of nearby contents such as clothing, carpets, drapes, bedding, couches, or vehicle seats.[98] Users were generally nearby when the incident occurred, were alerted by the sound of the explosion, and were able to take action to extinguish the fires while they were still small.[98] In 91 incidents, the fire spread was minor, meaning that the scorching or flames either self-extinguished or were extinguished very quickly by persons nearby.[98] Typically, in these incidents, the burned areas were 6 inches or less in diameter.[98] In 27 incidents, the fire spread was moderate, where the burned area was larger than 6 inches in diameter, but the fire was extinguished by occupants before the fire department arrived.[98] In 10 incidents, the fire spread was major and involved significant portions of a building, and required suppression by the fire department.[98] Typically, these incidents are what the fire service refers to as "room and contents" type fires, or larger.[98] In 67 of the incidents (34 percent), there was no fire spread, or fire spread was not evident in the reports reviewed.[98]
Even though there are knowns risks with unregulated
In January 2015 the US
Individuals sent to Saint Louis Hospital Burn Center in Paris, France from June 2016 to July 2017 for harms resulting from e-cigarettes were ten.
E-cigarette-related fires and explosions are a new risk to people and pets.
Users may alter many of the devices, such as using them to administer other drugs like cannabis.[3] E-liquid mixing is another way users tamper with e-cigarettes.[112] Mixing liquid in an unclean area runs the risk of contamination.[53] Users may add various flavorings and diluents.[112] Vodka or other forms of alcohol may also be added.[112] The addition of alcohol or nicotine could expose the user to more toxicants, especially when added in combinations.[112] Some ingredients in e-liquids could be flammable; this risk is more of concern for users who are inexperienced or do not use protective gear.[112] Users can adjust the voltage of some e-cigarettes.[112] The amount of vapor produced is controlled by the power of the battery, which has led some users to adjust their e-cigarettes to increase battery power to obtain a stronger nicotine "hit", but there is a small risk of battery explosion.[68] Some users add more or larger batteries to nonadjustable e-cigarettes, which may lead to battery leakage or explosion.[112] The FDA stated to only use batteries recommended for use with the device.[113] The FDA recommended to replace the batteries if they get damaged or wet.[113] The extent to which teens are altering e-cigarettes, such as dripping the liquids onto the atomizer to get more nicotine intake, is not known.[13]
Poisoning
The e-liquid can be toxic if swallowed, especially among small children.[11] Four adults died in the US and Europe, after intentionally ingesting liquid.[106] Two children, one in the US in 2014 and another in Israel in 2013, died after ingesting liquid nicotine.[118] A two-year-old girl in the UK in 2014 was hospitalized after licking an e-cigarette liquid refill.[119] Death from accidental nicotine poisoning is very uncommon.[120]
Calls to US poison control centers related to e-cigarette exposures involved inhalations, eye exposures, skin exposures, and ingestion, in both adults and young children.[121] Minor, moderate, and serious adverse effects involved adults and young children.[122] Minor effects correlated with e-cigarette liquid poisoning were tachycardia, tremor, chest pain and hypertension.[123] More serious effects were bradycardia, hypotension, nausea, respiratory paralysis, atrial fibrillation and dyspnea.[123] The exact correlation is not fully known between these effects and e-cigarettes.[123] The initial symptoms of nicotine poisoning may include rapid heart rate, sweating, feeling sick, and throwing up, and delayed symptoms include low blood pressure, seizures, and hypoventilation.[124] Rare serious effects included coma, seizure, trouble breathing, and heart attack.[125] Since June 2018, the US FDA observed a slight but noticeable increase in reports of seizures.[126] After examining poison control centers' reports between 2010 and early 2019, the FDA determined that, between the poison control centers and the US FDA, there were a total of 35 reported cases of seizures mentioning use of e-cigarettes within that timeframe.[126] Due to the voluntary nature of these case reports, there may be more instances of seizure in e-cigarette users than have been reported.[126]
Since 2011, accidental poisoning from e-liquids that contain nicotine have grown rapidly in the US.[127] From September 1, 2010, to December 31, 2014, 58% of e-cigarette calls to US poison control centers were related to children 5 years old or less.[122] Exposures for children below the age of 6 is a concern because a small dose of nicotine e-liquid may be fatal.[125] A 2014 Centers for Disease Control and Prevention report found 51.1% of the calls to US poison centers due to e-cigarettes were related to children under age 5, and about 42% of the US poison center calls were related to people age 20 and older.[128] E-cigarette calls had a greater chance to report an adverse effect and a greater chance to report a moderate or major adverse effect than traditional cigarette calls.[122] Most of the e-cigarette and traditional cigarette calls were a minor effect.[122] Severe outcomes were more than 2.5 times more frequent in children exposed to e-cigarettes and nicotine e-liquid than with traditional cigarettes.[129] E-cigarette sales were roughly equivalent to just 3.5% of traditional cigarette sales, but e-cigarettes represented 44% of the total number of e-cigarette and traditional cigarette calls to US poison control centers in December 2014.[122]
The US poison control centers reported 92.5% of children coming in contact with liquid nicotine was from swallowing during the period from January 2012 to April 2017.[125] From September 1, 2010, to December 31, 2014, the most frequent adverse effects to e-cigarettes and e-liquid reported to US poison control centers were: Ingestion exposure resulted in vomiting, nausea, drowsy, tachycardia, or agitation;[122] inhalation/nasal exposure resulted in nausea, vomiting, dizziness, agitated, or headache;[122] ocular exposure resulted in eye irritation or pain, red eye or conjunctivitis, blurred vision, headache, or corneal abrasion;[122] multiple routes of exposure resulted in eye irritation or pain, vomiting, red eye or conjunctivitis, nausea, or cough;[122] and dermal exposure that resulted in nausea, dizziness, vomiting, headache, or tachycardia.[122] The ten most frequent adverse effects to e-cigarettes and e-liquid reported to US poison control centers were vomiting (40.4%), eye irritation or pain (20.3%), nausea (16.8%), red eye or conjunctivitis (10.5%), dizziness (7.5%), tachycardia (7.1%), drowsiness (7.1%), agitation (6.3%), headache (4.8%), and cough (4.5%).[122] In nine reported calls, exposed individuals stated the device leaked.[122] In five reported calls, individuals used e-liquid for their eyes rather than use eye drops.[122] In one reported call, an infant was given the e-liquid by an adult who thought it was the infant's medication.[122] There were also reports of choking on e-cigarette components.[13]
From January 1, 2016, and April 30, 2016, the
In 2017, the US
Second-hand exposure
After the aerosol is inhaled, it is exhaled.[4] Emissions from e-cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different.[10] The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled aerosol.[79] The exhaled aerosol particle concentration is 5 times lower from an e-cigarette than from a traditional cigarette.[9] The density of particles in the e-cigarette vapor is lower than in cigarette smoke by a factor of between 6 and 880 times lower.[10]
For particulate matter emissions, e-cigarettes slightly exceeded the WHO guidelines, but emissions were 15 times less than traditional cigarette use.[118] In January 2014, 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 electronic cigarettes leads to emission of fine and ultrafine inhalable liquid particles, nicotine and cancer-causing substances into indoor air."[135] The dense vapor consists of liquid sub-micron droplets.[136] Substantial levels of particulate matter with a diameter of 2.5 μm are exhaled by vapers.[87]
Since e-cigarettes have not been widely used long enough for evaluation, the long-term health effects from the second-hand vapor are not known.[3] The short-term health effects from the second-hand vapor is also not known.[138] There is insufficient data to determine the impact on public health from e-cigarettes.[139] The potential harm to bystanders from e-cigarettes is unknown.[140] This is because no long-term data is available.[11] There are limited information on the health effects for children inhaling second-hand vapor.[141] Long-term effects for children inhaling second-hand vapor is not known.[141] Vaping has quickly gained public awareness with greater use among adolescents and adults, resulting in greater inhaled second-hand vapor for adolescents, children, and infants.[141] Second-hand vapor does vary depending on the e-liquid, the device and in the way it is used.[142] There is an array in e-cigarette designs, which has an impact on the amounts of ingredients being exposed to non-users.[87] Heavy advertising and promotion included the assertion that vaping would present little risk to bystanders.[143] E-cigarettes are marketed as "free of primary and second-hand smoke risk" due to no carbon monoxide or tar is expected to be generated during use.[144] However, there is a concern for the health impact of nicotine and other ingredients.[144] Exposure to second-hand vapor may be common.[141] Concerns exist that the increased rates of e-cigarette users who have never smoked could cause harms to public health from the increased nicotine addiction.[145] The growing experimentation with vaping among people under that age of 18 is especially concerning in respect to public health.[146] Ethical concerns arise from possibly vulnerable bystanders being exposed to the not yet known health effects of second-hand vapor.[145] Especially compared to the adverse effects of traditional cigarettes, the overall safety of e-cigarettes is not likely to justify significant public health concerns.[145] Overall, there is a possibility they may greatly harm the public's health.[147] Vaping in areas where smoking is banned indoors could be a move in the wrong direction for public health when considering air quality in addition to being unfavorable for an individual who may have quit nicotine use if they did not vape.[73] Some of the few studies examining the effects on health shown that being exposed to e-cigarette vapor may produce biological effects.[3] Their indiscriminate use may be a threat to public health.[148]
Some non-users have reported adverse effects from the second-hand vapor.[149] Second-hand vapor exhaled into the air by e-cigarette users can expose others to potentially harmful chemicals.[137] Vaping exposes non-users to particulate matter with a diameter of 2.5 μm, which poses health risks to non-users.[87] E-cigarettes produce propylene glycol aerosols at levels known to cause eye and respiratory irritation to non-users.[150] A 2014 study demonstrated that non-smokers living with vaping device users were exposed to nicotine.[151] A 2015 study concluded that, for indirect exposure, two chemicals—nicotine and propylene glycol—exceeded California Environmental Protection Agency exposure level standards for noncarcinogenic health effects.[150] Between January 2012 and December 2014, the FDA noted 35 adverse effect reports regarding second-hand vaping exposure.[152] A 2016 survey found a sizable percentage of middle and high school students were exposed to second-hand e-cigarette vapors.[87] It is recommended that adolescents stay away from being exposed to second-hand e-cigarette vapor.[49] A 2016 study showed that most participated coughed right away and briefly following a single exposure to e-cigarette vapor, while after 15 minutes it induced a diminished cough reflex sensitivity in healthy never-smokers.[153] Nicotine-free e-cigarette vapor did not have this effect.[153] The health effects of passive exposure to e-cigarettes with no nicotine, as well as the extent of exposure to these products, have just begun to be studied.[150] E-cigarettes that do not contain nicotine generate hazardous vapors[154] and could still present a risk to non-users.[155] Research has not evaluated whether non-users can have allergic reactions from nut potential allergens in e-cigarette aerosol.[150]
Since e-cigarettes do not burn tobacco, no
A 2017 review found that the "rapid production of new products has made it hard for the concerned stakeholders such as researchers in the public health field and policy makers to ensure that the products introduced to the public are safe for the users and non-users who are involuntarily exposed to e-cigarette vapors."[151] Little research exists on the exhaled particles, nicotine, and cancer-promoting chemicals into indoor air.[157] Concern exists that some of the mainstream vapor exhaled by e-cigarette users may be inhaled by bystanders, particularly indoors.[70] People living with e‐cigarette users had increased salivary concentrations of cotinine.[87] A small number of e-cigarette studies exist on the effect of indoor air quality done on human test subjects in natural settings.[151] Though, the available studies presented conflicting scientific evidence on the exact exposure from the e-cigarette vapor contents which may be a result of the contrasting methodology used during the research process.[151] Vaping can expose non-users to aldehydes and it reduced indoor air quality due to their released aldehydes.[87] Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted.[158] Thus, cardiocirculatory effects caused by carbon monoxide are not likely.[158] However, in an experimental study, e-cigarettes increased levels of carcinogenic polycyclic aromatic hydrocarbons in the surrounding air.[158] Passive inhalation of vapor might have significant adverse effects.[70] Though, e-cigarettes exposes non-users to nicotine but not to tobacco-related combustion toxicants.[70] Exposure to e-cigarette vapor can reduce lung function.[159]
E-cigarettes do pollute the air in the form of exhaled mainstream aerosol from people using e-cigarettes.[41] Nicotine, ultrafine particles, and products of heating propylene glycol and glycerin are increased in the air where e-cigarettes are being used, although, as expected, at lower levels than produced by smoking the same number of traditional cigarettes.[41] As with traditional cigarettes, however, when several people are using e-cigarettes indoors at the same time, the air can become polluted.[41] For example, levels of fine particulate matter (PM2.5) in a large hotel event room (4,023m3) increased from 2–3 μg/m3 to as high as 819 μg/m3 (interquartile range: 761–975 μg/m3) when 59–86 people were using e-cigarettes.[41] This level is comparable to a very (conventional tobacco) smoky bar or casino and dramatically exceeds the US Environmental Protection Agency annual time-weighted standard for PM2.5 of 12 μg/m3.[41]
Evidence has also shown that bystanders absorb nicotine when people around them use e-cigarettes at levels comparable with exposure to traditional cigarette second-hand smoke.[41] In a study of non-smokers living with nicotine e-cigarette users, those living with traditional cigarette smokers, or those living in homes where no one used either product, cotinine (a metabolite of nicotine) levels in bystanders' urine were significantly elevated in both the people exposed to second-hand e-cigarette aerosol and those exposed to second-hand tobacco smoke compared with people living in aerosol- and smoker-free homes.[41] Interestingly, the levels of elevated urinary cotinine in the two exposed groups were not significantly different (although the passive smokers had higher point estimates), despite the fact that the increase in air pollution in the smokers' homes was much higher than in the e-cigarette users' homes (geometric mean air nicotine concentrations of 0.13 μg/m3 in e-cigarette users' homes, 0.74 μg/m3 in smokers' homes, and 0.02 μg/m3 in the control homes).[41]
On the basis of emerging evidence, in 2014 the American Industrial Hygiene Association concluded that "e-cigarettes are not emission-free and that their pollutants could be of health concern for users and those who are exposed secondhand....[T]heir use in the indoor environment should be restricted, consistent with current smoking bans, until and unless research documents that they will not significantly increase the risk of adverse health effects to room occupants."[41] Similarly, in 2016 the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) updated its standard for "Ventilation for Acceptable Indoor Air Quality" to incorporate emissions from e-cigarettes into the definition of "environmental tobacco smoke," which is incompatible with acceptable indoor air quality.[41] As of April 2017[update], 12 US states and 615 localities had prohibited the use of e-cigarettes in venues in which traditional cigarette smoking was prohibited.[41]
There are benefits to banning vaping indoors in public and working areas, since there is a potential harm of renormalizing tobacco use in smoke-free areas, in addition to, vaping may result in spread of nicotine and other chemicals indoors.[160] E-cigarettes used in indoor environments can put at risk non-smokers to elevated levels of nicotine and aerosol emissions.[9] Non-smokers exposed to e-cigarette aerosol produced by a machine and pumped into a room were found to have detectable levels of the nicotine metabolite cotinine in their blood.[3] The same study stated that 80% of nicotine is normally absorbed by the user, so these results may be higher than in actual second-hand exposure.[3] A 2015 PHE report concluded that e-cigarettes "release negligible levels of nicotine into ambient air with no identified health risks to bystanders".[161] The e-cigarette vapor creates personal exposures that would warrant supervision.[162]
The available evidence demonstrates that the e-cigarette vapor emitted from e-cigarettes is not just "harmless water vapor" as is repeatedly stated in the advertising of e-cigarettes, and they can cause
A
Second-hand vapor exposes bystanders to numerous pollutants at amounts higher than background air.[155] A 2016 WHO (World Health Organization)report stated that "While some argue that exposure to SHA [second-hand aerosol] is unlikely to cause significant health risks, they concede that SHA can be deleterious to bystanders with some respiratory pre-conditions. It is nevertheless reasonable to assume that the increased concentration of toxicants from SHA over background [air] levels poses an increased risk for the health of all bystanders."[169] 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.[2] The report stated that "it is unknown if the increased exposure to toxicants and particles in exhaled aerosol will lead to an increased risk of disease and death among bystanders."[2] The British Medical Association (BMA) reported in 2013 that there are "concerns that the use of e-cigarettes could threaten the norm of not smoking in public places and workplaces."[170] Several medical organizations advocate that vaping be banned in public places and workplaces.[73] A 2014 review found it is safe to infer that their effects on bystanders are minimal in comparison to traditional cigarettes.[10] E-cigarette vapor has notably fewer toxicants than cigarette smoke.[3]
Third-hand
E‐cigarettes can be unsafe to non-users via third-hand exposure, including children, pregnant women, casino employees, housekeeping employees, and vulnerable groups.[87] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[171] E-cigarettes pose many safety concerns to children.[171] For example, indoor surfaces can accumulate nicotine where e-cigarettes were used, which may be inhaled by children, particularly youngsters, long after they were used.[171] A policy statement by the American Association for Cancer Research and the American Society of Clinical Oncology has reported that "Third-hand exposure occurs when nicotine and other chemicals from second-hand aerosol deposit on surfaces, exposing people through touch, ingestion, and inhalation".[12] A 2015 PHE report stated the amount of nicotine deposited was low and that an infant would have to lick 30 square meters to be exposed to 1 mg of nicotine.[161] There are no published studies of third-hand exposure from e-cigarettes, however initial data suggests that nicotine from e-cigarettes may stick to surfaces and would be hard to remove.[12] The extent of third-hand contamination indoors from e-cigarettes in real-world settings has not been established but would be of particular concern for children living in homes of e-cigarette users, as they spend more time indoors, are in proximity to and engage in greater activity in areas where dust collects and may be resuspended (e.g., carpets on the floor), and insert nonfood items in their mouths more frequently.[150]
Adolescents
Frequent vaping among middle and high school students has been correlated with cracked or broken teeth and tongue or cheek pain in a 2017 study relying on self-reporting.[141] There is probable evidence that coughing and wheezing is higher in adolescents who vape.[172]
Reported deaths
Direct exposure
There is a possibility that inhalation, ingestion, or skin contact can expose people to high levels of nicotine.[70] Concerns with exposure to the e-liquids include leaks or spills and contact with contaminants in the e-liquid.[76] This may be especially risky to children, pregnant women, and nursing mothers.[70] The FDA intends to develop product standards around concerns about children's exposure to liquid nicotine.[174] E-liquid exposure whether intentional or unintentional from ingestion, eye contact, or skin contact can cause adverse effects such as seizures, anoxic brain trauma, throwing up, and lactic acidosis.[175] The liquid does quickly absorb into the skin.[176] Local irritation can be induced by skin or mucosal nicotine exposure.[177] The nicotine in e-liquid can be hazardous to infants.[178] Even a portion of e-liquid may be lethal to a little child.[179] An excessive amount of nicotine for a child that is capable of being fatal is 0.1–0.2 mg/kg of body weight.[70] Less than a 1 tablespoon of contact or ingestion of e-liquid can cause nausea, vomiting, cardiac arrest, seizures, or coma.[180] An accidental ingestion of only 6 mg may be lethal to children.[42][148]
Children are susceptible to ingestion due to their curiosity and desire for oral exploration.[129] Children could confuse the fruity or sweet flavored e-liquid bottles for fruit juices.[84] E-liquids are packed in colorful containers[122] and children may be attracted to the flavored liquids.[27] More youth-oriented flavors include "My Birthday Cake" or "Tutti Frutti Gumballs".[118] Many nicotine cartridges and bottles of liquid are not child-resistant to stop contact or accidental ingestion of nicotine by children.[83] "Open" e-cigarette devices, with a refillable tank for e-liquids, are believed to be the biggest risk to young children.[180] If flavored e-cigarettes are let alone, pets and children could be attracted to them.[181] The FDA states that children are curious and put all sorts of things in their mouths.[182] Even if you turn away for a few seconds, they can quickly get into things that could harm them.[182] The FDA recommends that adults can help prevent accidental exposure to e-liquids by always putting their e-cigarettes and e-liquids up and away—and out of kids' and pets' reach and sight—every time you use them.[182] The FDA recommends to also ask family members, house guests, and other visitors who vape to keep bags or coats that hold e-cigarettes or e-liquids up and away and out of reach and sight of children and pets.[182] They recommend for children old enough to understand, explain to them that these products can be dangerous and should not be touched.[182] The FDA states to tell kids that adults are the only people who should handle these products.[182]
As part of ongoing efforts to protect youth from the dangers of nicotine and tobacco products, the US FDA and the
The US FDA announced on August 23, 2018, that all 17 manufacturers, distributors and retailers that were warned by the agency in May, have stopped selling the nicotine-containing e-liquids used in e-cigarettes with labeling or advertising resembling kid-friendly food products, such as juice boxes, candy or cookies that were identified through warning letters as being false or misleading.[185] Following the warning letters in May, the FDA worked to ensure the companies took appropriate corrective action – such as no longer selling the products with the misleading labeling or advertising – and issued close-out letters to the firms. The agency expects some of the companies may sell the products with revised labeling that addresses the concerns expressed in the warning letters.[185] "Removing these products from the market was a critical step toward protecting our kids. We can all agree no kid should ever start using any tobacco or nicotine-containing product, and companies that sell them have a responsibility to ensure they aren't enticing youth use. When companies market these products using imagery that misleads a child into thinking they're things they've consumed before, like a juice box or candy, that can create an imminent risk of harm to a child who may confuse the product for something safe and familiar," said FDA Commissioner Scott Gottlieb.[185]
There is growing evidence that vaping is hazardous to your health including depression which increases the risk of suicidal thoughts and suicide.[186] Nicotine toxicity is of concern when e-cigarette solutions are swallowed intentionally by adults as a suicidal overdose.[39] Seizures or convulsions are known potential side effects of nicotine toxicity and have been reported in the scientific literature in relation to intentional or accidental swallowing of e-liquid.[126] Six people attempted suicide by injecting e-liquid.[106] One adolescent attempted suicide by swallowing the e-liquid.[13] Three deaths were reported to have resulted from swallowing or injecting e-liquid containing nicotine.[106] An excessive amount of nicotine for an adult that is capable of being fatal is 0.5–1 mg/kg of body weight.[70] An oral lethal dose for adults is about 30–60 mg.[21] However the widely used human LD50 estimate of around 0.8 mg/kg was questioned in a 2013 review, in light of several documented cases of humans surviving much higher doses; the 2013 review suggests that the lower limit resulting in fatal events is 500–1000 mg of ingested nicotine, which is equivalent to 6.5–13 mg/kg orally.[187] Reports of serious adverse effects associated with acute nicotine toxicity that resulting in hospitalization were very uncommon.[149] Death from intentional nicotine poisoning is very uncommon.[120] Clear labeling of devices and e-liquid could reduce unintentional exposures.[122] Child-proof packaging and directions for safe handling of e-liquids could minimize some of the risks.[178] Some vaping companies willingly used child-proof packaging in response to the public danger.[115] In January 2016, the Child Nicotine Poisoning Prevention Act of 2015 was passed into law in the US,[188] which requires child-proof packaging.[189] The nicotine exposure rate in the US has since dropped by 18.9% from August 2016 to April 2017, following the Child Nicotine Poisoning Prevention Act of 2015, a federal law mandating child-resistant packaging for e-liquid, came into effect, on July 26, 2016.[125] The states in the US that did not already have a law, experienced a notable decline in the average number of exposures during the 9 months after the Child Nicotine Poisoning Prevention Act of 2015 came into effect compared to before it became law.[125] E-liquids have been observed in 2016 to include a press-and-turn feature similar to what is used for aspirin.[115] E-liquids that were normally available in bottles that were not regarded as child-resistant, have been reported in 2016.[115]
There was inconsistent labeling of the actual nicotine content on e-liquid cartridges from some brands,[3] and some nicotine has been found in "no nicotine" liquids.[79] A 2015 PHE report noted overall the labelling accuracy has improved.[190] Most inaccurately-labelled examples contained less nicotine than stated.[190] Due to nicotine content inconstancy, it is recommended that e-cigarette companies develop quality standards with respect to nicotine content.[4]
Because of the lack of production standards and controls, the pureness of e-liquid are generally not dependable, and testing of some products has shown the existence of harmful substances.[178] The German Cancer Research Center in Germany released a report stating that e-cigarettes cannot be considered safe, in part due to technical flaws that have been found.[42] This includes leaking cartridges, accidental contact with nicotine when changing cartridges, and potential of unintended overdose.[42] The Therapeutic Goods Administration (TGA) of Australia has stated that, "Some overseas studies suggest that electronic cigarettes containing nicotine may be dangerous, delivering unreliable doses of nicotine (above or below the stated quantity), or containing toxic chemicals or carcinogens, or leaking nicotine. Leaked nicotine is a poisoning hazard for the user of electronic cigarettes, as well as others around them, particularly children."[191]
Cannabinoid-enriched e-liquids require lengthy, complex processing, some being readily available online despite lack of quality control, expiry date, conditions of preservation, or any toxicological and clinical assessment.[192] It is assumed that vaporizing cannabinoids at lower temperatures is safer because it produces smaller amounts of toxicants than the hot combustion of a cannabis cigarette.[192] The health effects specific to vaping these cannabis preparations is largely unknown.[192]
Toxicology
The long-term
Carcinogenicity
Concerns about the carcinogenicity of e-cigarettes arise from both nicotine[200] and from other chemicals that may be in the vapor.[4] As regards nicotine, there is evidence from in vitro and animal research that nicotine may have a role as a tumor promoter, but carcinogenicity has not been demonstrated in vivo.[200] A 2014 Surgeon General of the United States report stated that the single relevant randomized trial "does not indicate a strong role for nicotine in promoting carcinogenesis in humans".[201] They concluded that "There is insufficient data to conclude that nicotine causes or contributes to cancer in humans, but there is evidence showing possible oral, esophageal, or pancreatic cancer risks".[201] Nicotine in the form of nicotine replacement products is less of a cancer risk than with smoking,[202] and they have not been shown to be associated with cancer in the real world.[200] Nicotine promotes metastasis by causing cell cycle progression, epithelial-to-mesenchymal transition, migration, invasion, angiogenesis, and avoidance of apoptosis in a number of systems.[203] Nicotine does promote the growth of blood vessels that supply tumors and it speeds tumor growth.[41] Whether long-term vaping can raise the chance for malignancy in individuals with a susceptibility for tumor growth is unknown.[204] The effects of nicotine on the sympathoadrenal system could stimulate the advancement of cancer in people who have cancer.[205]
Nicotine has been shown to induce DNA damage in the Escherichia colipol A+/pol− test.[206] Low concentrations of nicotine stimulate cell proliferation, while high concentrations are cytotoxic.[206] Nicotine decreases the tumor suppressor Chk2, which is activated by DNA damage.[206] The decrease in Chk2 in cells exposed to nicotine suggests that nicotine may be capable of overriding DNA damage checkpoint activation, disrupting genetic surveillance, and increasing the risk of oncogenesis.[206] There is strong evidence that some substances found in e-cigarette vapors such as formaldehyde and acrolein can induce DNA damage and mutagenesis.[207]
Nicotine promotes endothelial cell migration, proliferation, survival, tube formation, and nitric oxide (NO) production in vitro, mimicking the effect of other angiogenic growth factors.[206] In 2001, it was found that nicotine was a potent angiogenic agent at tissue and plasma concentrations similar to those induced by light to moderate smoking.[206] Effects of nicotine on angiogenesis have been demonstrated for a number of tumor cells, such as breast, colon, and lung.[206] Similar results have also been demonstrated in in vivo mouse models of lung cancer, where nicotine significantly increased the size and number of tumors in the lung, and enhanced metastasis.[206]
A 2014 study suggested that e-cigarette use may be a risk factor for lung cancer.
Evidence from experimental in vitro studies on cell cultures, in vivo studies on rodents as well as studies on humans inclusive of epidemiological studies indicate that nicotine may contribute in cancer development by stimulating a number of important processes.[206] Nicotine acts primarily by activation of nicotine acetylcholine receptors and nicotine binds to these receptors with a higher affinity than acetylcholine.[206] Furthermore, the tobacco-specific nitrosamines (TSNAs) NNN (N′-nitrosonornicotine) and NNK (4-(metylnitrosamino)-1-(3-pyridyl)-1-butanon) may be formed from nicotine after oral administration.[206] E-cigarettes deliver the potent lung carcinogen NNK.[41] Some evidence indicates that the NNK dose-response curve for cancer is highly nonlinear, with substantial increases in risk at low doses.[41] Known bladder carcinogens have been detected in the urine of e-cigarette users but not in non-users.[41] A 2015 study reported that the urine from users of e-cigarettes had very low levels of NNAL (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol), which may suggest that endogenous formation of TSNA after nicotine inhalation is negligible.[206] The data does indicate that TSNA may be formed internally after absorption of nicotine through the mucous membranes in the oral cavity and through the skin, while formation after lung absorption may be negligible.[206] Thus, the toxicokinetics of nicotine may depend on the route of administration.[206] The role of nicotine in carcinogenesis is of great importance in the evaluation of potentially harmful effects from non-tobacco related sources of nicotine, such as e-cigarettes.[206]
Nicotine has been shown to induce chromosomal aberration, chromatid exchange, single-strand DNA strand breaks, and micronuclei in vitro.[206] Oxidative stress is probably involved since the effects are reduced in the presence of antioxidants.[206] The finding that the effects decrease after co-incubation with a nicotinic acetylcholine receptor antagonist indicates a receptor-dependent pathway for induction of oxidative stress.[206]
The interaction of nicotine with nicotinic acetylcholine receptors activates signaling pathways that result in a number of reactions, such as increased cell proliferation and cell survival.[206] Although nicotinic acetylcholine receptors are the primary receptors, binding of nicotine to β-ARs and EGFRs may also be important.[206] Nicotine induces epithelial–mesenchymal transition, which is one of the vital steps for the acquisition of malignant phenotype.[206] This transition allows the cell to acquire migratory properties, which may facilitate cancer metastases.[206] Moreover, nicotine induces changes that mimic the effects of angiogenic growth factors.[206]
At present, it is not possible to draw a conclusion whether nicotine itself may act as a complete carcinogen.
There is no long-term research concerning the cancer risk related to the potentially small level of exposure to the identified
Since nicotine-containing e-liquids are made from tobacco they may contain impurities like cotinine, anabasine, anatabine, myosmine and beta-nicotyrine.[11] The health implications of nicotine-related impurities are not known.[150] A 2016 review found "Some studies have demonstrated that 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 found in e-cigarette refill liquids. The molecules can lead to mutations in genes such as Ras (vital function in signal transduction of cell proliferation), p53 and Retinoblastoma (with roles as tumour suppressors) as these molecules can form adducts with cellular DNA."[84] The majority of e-cigarettes evaluated included carcinogenic TSNAs; heavy metals such as cadmium, nickel, and lead; and the carcinogen toluene.[70] However, in comparison to traditional cigarette smoke, the toxic substance levels identified in e-cigarette vapor were 9- to 450-fold less.[70] E-liquid with tin was cytotoxic.[215] E-cigarettes cannot be considered absolutely safe because there is no safe level for carcinogens.[216]
A 2014 review found higher levels of carcinogens and toxicants than in an FDA regulated nicotine inhaler, suggesting that regulated FDA devices may deliver nicotine more safely.[9] In 2014, the World Lung Foundation (now known as Vital Strategies) stated that "Researchers find that many e-cigarettes contain toxins, contaminants and carcinogens that conflict with the industry's portrayal of its products as purer, healthier alternatives. They also find considerable variations in the amount of nicotine delivered by different brands. None of this information is made available to consumers so they really don't know what they are ingesting, or how much."[157]
A 2014 review found "Various chemical substances and ultrafine particles known to be toxic, carcinogenic and/or to cause respiratory and heart distress have been identified in e-cigarette aerosols, cartridges, refill liquids and environmental emissions."[4] Few of the methods used to analyze the chemistry of e-cigarettes in the studies the review evaluated were validated.[4] Many variables affect the levels of toxicants in the e-cigarette vapor, including the design, the type of liquid, and user behavior.[149] The FDA in 2009 analyzed e-liquid cartridge samples[200] from two brands of e-cigarettes,[217] which were NJOY and Smoking Everywhere.[216] Their analysis of the e-cigarette samples showed that the products contained detectable levels of known carcinogens and toxic chemicals to which users could potentially be exposed.[218] Diethylene glycol was detected in one cartridge at approximately 1%.[218] Diethylene glycol, an ingredient used in antifreeze, is toxic to humans.[218] The source of the diethylene glycol contamination is not clear but could reflect the use of non-pharmaceutical grade propylene glycol.[36] On July 22, 2009,[217] the FDA warned that e-cigarettes may present a health risk.[9]
Other chemicals in vapor on the California Prop 65 list of chemicals known to cause cancer or reproductive harm include benzenene and isoprene.[219]
Propylene glycol and other content
The primary base ingredients of the liquid solution is
Some e-cigarette products had
The toxicity of e-cigarettes and e-liquid can vary greatly, as there are differences in construction and materials in the delivery device, kind and origin of ingredients in the e-liquid, and the use or non-use of good manufacturing practices and quality control approaches.[195] If exposure of aerosols to propylene glycol and glycerin rises to levels that one would consider the exposure in association with a workplace setting, it would be sensible to investigate the health of exposed persons.[162] The short-term toxicity of e-cigarette use appears to be low, with the exception for some people with reactive airways.[79]
Flavoring
The essential propylene glycol and/or glycerin mixture may consist of natural or artificial substances to provide it flavor.[79] Health effects of e-cigarette flavorings are not entirely known.[226] There is very limited toxicological data on inhaling flavoring additives.[166] Flavorings can be a significant part of toxicants in the e-cigarette vapor.[227] Each flavor has a different chemical composition, and therefore, probably, a distinct composition of toxicant emissions.[227] The cytotoxicity of e-liquids varies,[78] and contamination with various chemicals have been detected in the liquid.[79] Some liquids were very toxic and others had little or no cytotoxicity.[78] The cytotoxicity is mostly due to the amount and number of flavors added.[78] Since nicotine has a bitter taste, nicotine e-liquids contain chemicals to cover up the nicotine taste.[68] The liquids contain aromatic substances like tobacco, fruit, vanilla, caramel, and coffee.[79] Generally, these additives are imprecisely described, using terms such as "vegetable flavoring".[79] Although they are approved for human consumption there are no studies on the short-term or long-term effects of inhaling them.[79] The safety of inhaling flavors is mostly unknown,[77] and their safety has not been determined by the Flavor and Extract Manufacturers Association.[106] The majority of flavorings in e-liquids have not been investigated for toxicity by means of inhalation.[228] A 2017 review found the Flavor and Extract Manufacturers Association of the USA, a trade association of flavor ingredient manufacturers which evaluates the safety of food flavorings, has identified 1037 flavoring agents as potential respiratory hazards due to possible volatility and respiratory irritant properties. Common e-cig flavoring agents on this list include, but are not limited to: diacetyl, acetoin, 2,3-pentanedione (buttery flavors), camphor and cyclohexanone (minty flavors), benzaldehyde (cherry or almond flavors), cinnamaldehyde (cinnamon flavor), cresol (leathery or medicinal flavor), butyraldehyde (chocolate flavor), and isoamyl acetate (banana flavor)."[166] A 2017 review stated, "the implication by manufacturers that flavor ingredients used in e-cigarettes and related devices (e.g. hookahs) are safe for inhalation because they have FEMA GRAS™ status for use in food has been stated to be 'false and misleading' by FEMA."[51]
The extensive and unregulated use of flavoring additives may pose health concerns.[166] Many flavors are irritants.[209] The limited data available on their flavoring agents suggest that the majority of flavorings could lead to significant health risks from long-term use, particularly the ones that are sweet.[73] In some cases e-liquids contain very large amounts of flavorings, which may cause irritation and inflammation on respiratory and cardiovascular systems.[75] A 2016 study of 30 e-cigarette products in the US market found that 13 were more than 1% flavor chemicals by weight, some of which were of potential toxicological concern (e.g., cause respiratory irritation).[229] Some flavors are regarded as toxic and a number of them resemble known carcinogens.[79] The cytotoxicity of some flavors such as strawberry seems to be greater than others.[230] A 2016 study of five flavors across six types of e-cigarettes found that flavors significantly affected the in vitro toxicity profile and the strawberry-flavored product was the most toxic.[229] Some artificial flavors are known to be cytotoxic.[79] Unflavored vapor is less cytotoxic than flavored vapor.[231] A 2012 study demonstrated that in embryonic and adult cellular models, some substances of the e-cigarette vapor such as flavoring not found in tobacco smoke were cytotoxic.[232] The caffeine exposures from vaping are approximately at amounts considerably less than in comparison with consuming caffeinated beverages.[233] There is very limited information available regarding the effects of breathing in caffeine.[233] The evidence is unclear that particular flavorings carry health risks, though there are indications that breathing in some may be a source of avoidable risks.[234]
Certain flavorings contain
The
Formaldehyde
The IARC has categorized
Battery output voltage influences the level of the carbonyl substances in the e-cigarette vapor.[225] Some newer e-cigarette models let users boost the amount of vapor and nicotine provided by modifying the battery output voltage.[225] E-cigarettes that were modified to boost the vapor production are more dangerous to use.[67] High-voltage e-cigarettes could subject users to large amounts of carbonyls.[225] E-cigarettes with higher voltages (5.0 V[78]) can emit carcinogens including formaldehyde at levels comparable to cigarette smoke,[204] while reduced voltages (3.0 V[4]) generate aerosol with levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than in cigarette smoke.[225] The average amount of formaldehyde in vapor from high-voltage devices is higher than the average amount of formaldehyde released from cigarettes.[48] "Dripping", where the liquid is dripped directly onto the atomizer, can create carbonyls including formaldehyde.[250]
Controversy exists regarding the specific amount of formaldehyde expected to be breathed in by the user.[227] A 2015 PHE report found that normal e-cigarette use generates very low levels of aldehydes.[251] Normal usage of e-cigarettes generates very low levels of formaldehyde,[231] and at normal settings they generate very low levels of formaldehyde.[251] A 2018 PHE report found that at normal usage temperatures, aldehyde in the e-cigarette vapor is at negligible amounts in comparison with smoking.[252] Later-generation and "hotter" e-cigarettes may generate equal or higher levels of formaldehyde compared to smoking.[208] A 2015 study analyzing 10 puffs found that vaping at a high voltage (5.0 V) generates formaldehyde in e-cigarette vapor; they inferred from the finding that the user vaping at high voltage with 3 ml of e-liquid daily would inhale 14.4±3.3 mg of formaldehyde daily in formaldehyde-emitting chemicals.[78] This was estimated to be a lifetime cancer risk of 5 to 15 times greater than compared with long-term smoking.[78] A 2015 study using a third-generation device, very low levels of formaldehyde were produced on lower power, although, when adjusted to a maximum power setting, levels were greater than with cigarette smoke.[231] Running at a higher power (temperature) not only increases nicotine delivery, but also increases the amount of formaldehyde and other aldehydes that are naturally produced by heating up propylene glycol or glycerin and other toxicants produced in the e-cigarette aerosol.[41] A 2015 PHE report found that by applying maximum power and increasing the time the device is used on a puffing machine, e-liquids can thermally degrade and produce high levels of formaldehyde.[251] Users detect the "dry puff" (also known as a "dry hit"[253]) and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[254] However, e-cigarette users may learn to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[68]
Nicotine
Nicotine is regarded as a potentially
E-cigarettes provide nicotine to the blood quicker than nicotine inhalers.
Aerosol composition
The
E-cigarettes consist of fine and ultrafine particles of particulate matter,[3] in the form of an aerosol.[208][4] The aerosol (mist[79]) produced by an e-cigarette is commonly but inaccurately called vapor.[4] In physics, a vapor is a substance in the gas phase whereas an aerosol is a suspension of tiny particles of liquid, solid or both within a gas.[4] The word "vaping" is not technically accurate when applied to e-cigarettes.[136] The aerosol is made-up of liquid sub-micron particles of condensed vapor; thus, the users of these devices are rather "aerosolizing."[136] This aerosol that is produces looks like cigarette smoke to some extent.[133] After a puff, inhalation of the aerosol travels from the device into the mouth and lungs.[4] 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 hugely great number of different chemical vapor combinations potentially breathed in by the user.[166]
The particles produced from vaping are comparable in particle-size distribution and number of particles to cigarette smoke, with the majority of them in the ultrafine range.[3] Some e-cigarettes released more particles than cigarette smoke.[3] A 2014 review found that fine particles can be chemically intricate and not uniform, and what a particle is made of, the exact harmful elements, and the importance of the size of the particle is mostly unknown.[3] They found that because these things are uncertain, it is not clear whether the ultrafine particles in e-cigarette vapor have health effects similar to those produced by traditional cigarettes.[3] A 2014 WHO report found e-cigarettes release a lower concentration of particles than traditional cigarettes.[2]
Metals
There is limited evidence on the long-term exposure of metals.[10] Exposure to the levels and kinds of metals found in the aerosol relies upon the material and other manufacturing designs of the heating element.[39] E-cigarettes contain some contamination with small amounts of metals in the emissions but it is not likely that these amounts would cause a serious risk to the health of the user.[10] According to a 2018 PHE report, metals emissions no matter how small, are not needed.[234] They further stated, "EC [e-cigarettes] that generate minimal metal emissions should become an industry standard."[221] The device itself could contribute to the toxicity from the small amounts of silicate and heavy metals found in the liquid and vapor,[250] because they have metal parts that come in contact with the e-liquid.[10] Low levels of possibly harmful chromium, lead, and nickel metals have been found in the emissions.[39] Chromium and nickel nanoparticles have also been found.[3] Copper nanoparticles can induce mitochondrial and DNA injury in lung fibroblasts.[267] DNA repair can be impeded by titanium dioxide nanoparticles from the e-cigarette vapor.[268] This was demonstrated that the titanium dioxide nanoparticles induced single-strand breaks and produced oxidative stress in the DNA of A549 cells.[268] The risk of inhaling nanoparticles is an area of concern.[178] The toxicity of nanoparticles is unknown.[269] Metals including nickel, cadmium, lead and silicate can found in the e-cigarette vapors, and are thought to be carcinogenic, nephrotoxic, neurotoxic, and hemotoxic.[84] Heavy metals are correlated with serious health issues.[18] Inhaling lead can induce serious neurologic injury, notably to the growing brains of children.[18]
Metals may adversely affect the nervous system.[116] Metals found in the e-cigarette vapor may induce cell damage and initiate inflammatory cytokine such as in human lung fibroblasts.[238] A 2017 review found "E-cigarette aerosols and copper nanoparticles induced mitochondrial ROS production, mitochondrial stress (reduced stability of OxPhos electron transport chain (ETC) complex IV subunit) and DNA fragmentation in lung fibroblasts."[223] A 2013 review found metallic and nanoparticles are associated with respiratory distress and disease.[144] A 2014 review found considerable amounts of tin, metals, and silicate particles that came from various components of the e-cigarette were released into the aerosol, which result in exposure that could be higher than with cigarette smoke.[70] A 2013 study found metal particles in the aerosol were at levels 10-50 times less than permitted in inhalation medicines.[11] A 2014 review suggested that there is no evidence of contamination of the aerosol with metals that justifies a health concern.[162] Cadmium that have been found in the e-cigarette vapor is linked to low sperm density.[230]
First-generation devices
E-cigarettes resembling cigarettes typically produce much less blood nicotine levels.[226] When compared to traditional cigarettes older devices usually delivered low amounts of nicotine.[12] E-cigarette use can be associated with a substantial dispersion of nicotine, thus generating a plasma nicotine concentration which can be comparable to that of traditional cigarettes.[72] This is due to the minute nicotine particles in the e-cigarette vapor, which permit quick delivery into the bloodstream.[72] The nicotine delivered from e-cigarettes enters the body slower than traditional cigarettes.[158] Studies suggest that inexperienced users obtain moderate amounts of nicotine from e-cigarettes.[270] Concerns were raised over inconsistent amounts of nicotine delivered when drawing on the device.[271]
Newly developed devices
Tank or adjustable e-cigarettes can raise nicotine levels as high as traditional cigarettes.[226] Later-generation e-cigarettes give nicotine more effectively than first-generation e-cigarettes.[74] Later-generation models with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[12] Some e-cigarette tank devices with stronger batteries heat solutions to greater temperatures, which may raise levels of nicotine in the blood similar to those of traditional cigarettes.[39] Research suggests that experienced e-cigarettes users are able to get as much nicotine from e-cigarettes as traditional cigarettes.[12] Later-generation e-cigarettes containing sufficient nicotine elevate heart rate comparable to traditional cigarettes.[244] Later-generation devices delivery 35% to 72% more nicotine than compared with first‐generation devices.[87] Second-generation e-cigarettes raised the heart rate and blood pressure similar to traditional cigarettes.[272] As there are design changes, later-generation devices may provide nicotine similar to traditional cigarettes with a highly concentrated amount potential straight to the brain.[73] Such devices may largely reshape the effects on cardiac safety, misuse, and addiction.[73] There is not much research on fourth-generation devices.[38]
Concerns
The health effects of long-term nicotine use is unknown.
Nicotine can weaken
A 2016 review found "Evidence from experimental animal models clearly demonstrate nicotine's ability to enhance existing tissue injury and diseases such as cancer, cardiovascular disease, stroke, pancreatitis, peptic ulcer, renal injury and developmental (e.g. pulmonary, reproductive and central nervous system) abnormalities."[288] The consequence of nicotine use in autoimmunity has been conflicting.[289] Nicotine could have cancer-promoting properties, therefore long-term use may not be harmless.[112] Nicotine may result in neuroplasticity variations in the brain.[176] Nicotine has been demonstrated to alter the amounts of brain-derived neurotrophic factor in humans.[290] Nicotine could make cancer therapies less effective.[53] Based on in vitro and in vivo effects of nicotine, patients should be advised not to use nicotine products during cancer treatment unless it is temporarily needed to stop tobacco smoking.[206] Nicotine can suppress appetite.[291] Nicotine users will probably gain weight after using less nicotine.[292] A long-term risk from vaping a base containing nicotine is nicotine dependence.[141]
Youth concerns
Children are more sensitive to nicotine than adults.
Nicotine changes the way
In 2015 the psychological and behavioral effects of e-cigarettes were studied using whole-body exposure to e-cigarette vapor, followed by a series of biochemical and behavioral studies.
Comparison of levels of toxicants in e-cigarette aerosol
Toxicant | Range of content in nicotine inhaler mist (15 puffs∗) | Content in aerosol from 12 e-cigarettes (15 puffs∗) | Content in traditional cigarette micrograms (μg) in smoke from one cigarette |
---|---|---|---|
Formaldehyde (μg) | 0.2 | 0.2-5.61 | 1.6-52 |
Acetaldehyde (μg) | 0.11 | 0.11-1.36 | 52-140 |
Acrolein (μg) | ND | 0.07-4.19 | 2.4-62 |
o-Methylbenzaldehyde (μg) | 0.07 | 0.13-0.71 | — |
Toluene (μg) | ND | ND-0.63 | 8.3-70 |
p- and m-Xylene (μg) | ND | ND-0.2 | — |
NNN (ng) | ND | ND-0.00043 | 0.0005-0.19 |
Cadmium (ng) | 0.003 | ND-0.022 | — |
Nickel (ng) | 0.019 | 0.011-0.029 | — |
Lead (ng) | 0.004 | 0.003-0.057 | — |
Abbreviations: μg, microgram; ng, nanogram; ND, not detected.[78]
∗Fifteen puffs were chosen to estimate the nicotine delivery of one traditional cigarette.[78]
Effects on breathing and lung function
The risks to the lungs are not fully understood,
Exposure to inhaled nicotine-containing e-cigarette fluids triggered effects normally associated with the development of a chronic obstructive lung disease-like tissue damage in a nicotine-dependent manner.
The long-term effects regarding respiratory flow resistance are unknown.[85] The available evidence indicates that e-cigarettes may result in respiratory effects that are like as well as unlike that of traditional cigarettes.[166] E-cigarettes reduce lung function, but to a much lower extent than with traditional cigarettes.[301] E-cigarettes could harm the respiratory system.[79] Vaping induces irritation of the upper and lower respiratory system.[48] The immediate effects of e-cigarettes after 5 minutes of use on pulmonary function resulted in considerable increases in resistance to lung airflow.[74] A 2013 review found an instant increase in airway resistance after using a single e-cigarette.[79] Higher levels of exhaled nitric oxide were found among test subjects in a 2014 study who vaped with a base of nicotine which was associated with lung inflammation.[151] Any reported harmful effects to cardiovascular and respiratory functions after short-term use of e-cigarettes were appreciably milder in comparison to cigarette smoke.[10] When used in the short-term, an e-cigarette resulted in a rise of respiratory resistance comparatively to traditional cigarettes.[85] E-cigarette use could result in respiratory diseases among youth.[302] Evidence from animal studies indicate that children or adolescents exposed to second-hand vapor containing nicotine may impede their lung development.[56] Adolescents with asthma who vape could have greater odds of having a higher number of respiratory symptoms and aggravations in contrast to their peers who do not vape.[303] Adolescents and children with other respiratory ailments who vape may be at greater chance for aggravating of respiratory symptoms.[304] A 2018 PHE report found "There have been some studies with adolescents suggesting respiratory symptoms among EC experimenters. However, small scale or uncontrolled switching studies from smoking to vaping have demonstrated some respiratory improvements."[305] A 2017 review found "among a population of 11th-grade and 12th-grade students in California, e-cigarette use was associated with twice the risk of respiratory symptoms, and the risk increased with more frequent e-cigarette use."[147]
Comparable to a traditional cigarette, e-cigarette particles are tiny enough to enter the
As with cardiovascular disease, evidence consistently indicates that exposure to e-cigarette aerosol has adverse effects on lungs and pulmonary function.[41] Repeated exposure to acrolein, which is produced by heating the propylene glycol and glycerin in e-liquids, causes chronic pulmonary inflammation, reduction of host defense, neutrophil inflammation, mucus hypersecretion, and protease-mediated lung tissue damage, which are linked to the development of chronic obstructive pulmonary disease.[41] E-cigarette aerosol also exposes users to highly oxidizing free radicals.[41] The chemical characteristics of the short-lived free radicals and long-lived free radicals produced from e-cigarettes is unclear.[193] Animal studies have also shown that e-cigarettes increase pulmonary inflammation and oxidative stress while inhibiting the immune system.[41]
Consistent with these experimental results, people who used e-cigarettes experienced decreased expression of immune-related genes in their nasal cavities, with more genes suppressed than among cigarette smokers, indicating immune suppression in the nasal mucosa.[41] E-cigarette use upregulates expression of platelet-activating factor receptor (PAFR) in users' nasal epithelial cells; PAFR is an important molecule involved in the ability of S.pneumoniae, the leading cause of bacterial pneumonia, to attach to cells it infects (adherence).[41] In light of the immunosuppressive effects observed in nasal mucosa, there is concern that e-cigarette use will predispose users toward more severe respiratory infections, as has been demonstrated in mouse studies.[41]
Given these effects, it is not surprising that e-cigarette use is associated with a doubling of the risk of symptoms of chronic bronchitis among US high school juniors and seniors with higher risk associated with higher use; these risks persisted among former users.[41] Similarly, current e-cigarette use was associated with an increased diagnosis of asthma among Korean high school students among current (e-cigarette users who were never cigarette smokers).[41] E-cigarette users were also more likely to have had days absent from school due to severe asthma symptoms.[41]
Vaping is reportedly tied to a range of lung injuries which include hypersensitivity pneumonitis (HP), diffuse alveolar hemorrhage (DAH), acute eosinophilic pneumonia (AEP), diffuse alveolar damage, organizing pneumonia (OP), lipoid pneumonia, and giant cell interstitial pneumonia (GIP).[306]
2019–2020 vaping lung injury outbreak
Since 2019, an ongoing
On September 6, 2019, Dr. Dana Meaney-Delman, serving as the incident manager of the
Thickening agents were used to dilute vape oils.[319] There has been an increase in attention to companies that sell diluent products that are made with vitamin E acetate.[319] Previously, vitamin E was used in low concentrations, or lower than 20% of the formula in vape cartridges.[319] As a result of a limited availability of cannabis in California as well as high demand, illicit sellers had used about 50% or higher of diluent thickeners in their formulas to bulk up tiny potency vape cartridges.[319] In September 2019, New York Governor Andrew Cuomo instructed the state health department to issue subpoenas against three sellers of thickening agents used in illicit vaping products.[320]
The e-cigarette industry is placing the blame on illicit vaping liquids for the lung injuries.[321] Juul Labs stated that some news reports state that several cases of lung illness are associated with vaping THC, found in cannabis, "a Schedule 1, controlled substance that we do not sell."[322] The CDC recommends that the public should consider not using any vaping products during their investigation, particularly those containing THC from informal sources like friends, or family, or in-person or online dealers as of November 20, 2019.[311] The US FDA considers it prudent to avoid inhaling vitamin E acetate.[316] On September 6, 2019, the US FDA stated that because consumers cannot be sure whether any THC vaping products may contain vitamin E acetate, consumers are urged to avoid buying vaping products on the street, and to refrain from using THC oil or modifying/adding any substances to products purchased in stores.[316]
Cardiovascular effects
There is accumulating evidence on their long-term cardiovascular effects. A 2023 systematic review and meta-analysis finds e-cigarettes cause a significant, potentially harmful effect on many cardiovascular parameters.
Preliminary studies have shown that using a nicotine containing e-cigarette for just five minutes causes similar lung irritation, inflammation, and effect on blood vessels as smoking a traditional cigarette, which may increase the risk of a
E-cigarettes adversely impact the cardiovascular system.[41] Although the specific role of nicotine in cardiovascular disease remains debated, nicotine is not the only biologically active component in e-cigarette aerosol.[41] E-cigarettes work by creating an aerosol of ultrafine particles to carry nicotine deep into the lungs.[41] These particles are as small as—and sometimes smaller than—those in traditional cigarettes.[41] These ultra fine particles are themselves biologically active, trigger inflammatory processes, and are directly implicated in causing cardiovascular disease and acute cardiovascular events.[41] The dose-response effect for exposure to particles is nonlinear, with substantial increases in cardiovascular risk with even low levels of exposure to ultrafine particles.[41] For example, exposure to second-hand cigarette smoke has nearly as large an effect on many risk factors for cardiovascular disease and the risk of acute myocardial infarction as does being an active smoker.[41] Like traditional cigarette smokers, e-cigarette users experience increased oxidative stress and increases in the release of inflammatory mediators.[41] E-cigarette aerosol also induces platelet activation, aggregation, and adhesion.[41] All these changes are associated with an increased risk of cardiovascular disease.[41] These physiological changes are manifest in rapid deterioration of vascular function following use of e-cigarettes.[41] E-cigarette and traditional cigarette smoking in healthy individuals with no known cardiovascular disease exhibit similar inhibition of the ability of arteries to dilate in response to the need for more blood flow.[41] This change reflects damage to the lining of the arteries (the vascular endothelium), which increases both the risk of long-term heart disease and an acute event such as a myocardial infarction (heart attack).[41] Using e-cigarettes is also accompanied by a shift in balance of the autonomic (reflex) nervous system toward sympathetic predominance, which is also associated with increased cardiac risk.[41] Daily e-cigarette use is correlated with an increased risk of a heart attack (myocardial infarction) in health surveys.[41]
There is little evidence indicating that using e-cigarettes rather than continue to smoke will help periodontal disease.[331] Vaping with or without nicotine or flavoring may help cause periodontal disease.[332] Nicotine as well as their flavoring may be damaging to periodontal ligament, stem cells, and gingival fibroblasts in cultures as a result of creation of aldehydes and/or carbonyls from e-cigarette vapor.[332] It is possible that e-cigarettes could harm the periodontium because of the effects of nicotine on gum tissues and the immune system.[333] Vaping resulted in nicotine stomatitis, hairy tongue, and angular cheilitis.[334] Vaping can cause oral mucosal lesions.[335] No compelling evidence from vaping indicates it directly causes oral cancer.[334]
Other effects
Vaping long-term is anticipated to raise the risk of developing some of the diseases linked to smoking.
E-cigarettes and pregnancy
It is discouraged for pregnant and breastfeeding females to substitute cigarettes with e-cigarettes.[18] It is recommended that females who smoke during pregnancy to quit using cigarettes.[18] Current guidelines state that nicotine products (such as patches, gum and mouth spray) can help. Research from the UK suggests that pregnant women could also consider e-cigarettes.[336][337] There is concern for breastfeeding females using e-cigarettes, due to the lack of data on propylene glycol transferring to breastmilk.[79] Nicotine could also impact the development of the infant since it is a teratogen.[338] It is discouraged to use e-cigarettes while breastfeeding infants or young children.[18] The consequences of vaping on infants feeding on breast milk is uncertain.[18]
Public perceptions
Marketing and advertisement play a significant role in the public's perception of e-cigarettes.[145] Some tobacco users think vaping is safer than tobacco or other smoking cessation aids.[339] It is generally considered by users that e-cigarettes are safer than tobacco.[246] Emerging research indicates that vaping is not as safe as previously thought.[340] Many users think that e-cigarettes are healthier than traditional cigarettes for personal use or for other people.[27] Many youth believe vaping is a safe substitute to traditional cigarettes.[181] A 2016 review suggests "that the perceived health risks, specific product characteristics (such as taste, price and inconspicuous use), and higher levels of acceptance among peers and others potentially make e-cigarettes initially more attractive to adolescents than tobacco cigarettes.[341] Youths who have lower harm perceptions may be particularly susceptible to e-cigarette and polytobacco use, conversely those who perceive e-cigarettes as more harmful would be less likely to use them.[342] Usually, only a small proportion of users are concerned about the potential adverse health effects or toxicity of e-cigarettes.[27] A nation-wide US survey among adults found 11.1% thought vaping during pregnancy was not as harmful as smoking, 51.0% thought it was as harmful, 11.6% thought it would be an increased harm, and 26.2% were unsure.[343] A 2015 study showed that 60% of all adolescence stated vaping were safe or a minor health risk and that 53.4% considered vaping safer than cigarette smoking.[35] A 2017 review found, based on literature from January 2006 to October 2016, examining perceptions regarding vaping during pregnancy, that the majority of respondents perceived vaping can carry health risks to mother and child, but also thought they may be less harmful than traditional cigarettes.[344] Many adolescent asthmatics have a favorable view of vaping.[166] A 2016 survey of people 14 years of age and up in Germany reported that 20.7% of participants consider e-cigarettes to be not as harmful as cigarettes, 46.3% just as harmful, and 16.1% thought they were more harmful, and 17.0% gave no answer.[345] In terms of harm perception, a 2016 study found that flavored e-cigarette use reduced the prevalence of perception of the dangers of tobacco use among youth.[229] Another 2016 study found more nuanced results, demonstrating that tobacco flavor increased harm perception while fruit and sweet flavors decreased harm perception among UK adolescents.[229] Similarly, a 2016 study in the US found that, for US adolescents, fruit-flavored e-cigarettes were perceived to be less harmful than tobacco flavored ones.[229] There is indication that an individual's perception of a substance's potential harms and benefits and their behavior of use is influenced by the availability of information discussing the health effects of that substance.[346] A 2015 analysis reports that 34.20% (8433/24,658) of American youth sampled believe that e-cigarettes are less harmful than cigarettes, and 45% (11,096/24,658) are not sure.[346]
As of 2018[update], under 50% of adults in the UK believe vaping is less harmful than smoking.[347] Action on Smoking and Health (ASH) in the UK found that in 2015, compared to the year before, "there has been a growing false belief that electronic cigarettes could be as harmful as smoking".[348] Among smokers who had heard of e-cigarettes but never tried them, this "perception of harm has nearly doubled from 12% in 2014 to 22% in 2015."[348] ASH expressed concern that "The growth of this false perception risks discouraging many smokers from using electronic cigarettes to quit and keep them smoking instead which would be bad for their health and the health of those around them."[348] A 2015 PHE report noted that in the US belief among respondents to a survey that vaping was safer than smoking cigarettes fell from 82% in 2010 to 51% in 2014.[349] The report blamed "misinterpreted research findings", attracting negative media coverage, for the growth in the "inaccurate" belief that e-cigarettes were as harmful as smoking.[350] A 2017 review noted that there is a public misconception that vaping is safer than cigarette smoking.[351] A 2016 review noted that the increasing use of e-cigarettes may be due in part to "the misperception that e-cigarettes are a safer alternative to traditional cigarettes."[352] A 2014 review noted that "users do not appear to fully understand their health risks."[259] Beliefs on vaping may be surpassing our scientific knowledge of these products.[353] Proponents of vaping have stated that nicotine is 'as safe as caffeine'.[354] E-cigarettes are believed to be considerably safer compared with smoking and nicotine is thought to be comparatively harmless.[355] As a consequence, it is believed to be without risk to use them indoors or near babies.[355]
A 2014 worldwide survey found that 88% of respondents stated that vaping were less harmful than cigarette smoke and 11% believed that vaping were absolutely harmless.[356] A 2013 four-country survey found higher than 75% of current and former smokers think e-cigarettes are safer than traditional cigarettes.[74] A 2017 report found that among high income countries, Republic of Korea in 2016 was 66%, the US in 2016 was 37%, Netherlands in 2015 was 32%, Canada in 2016 was 30%, the UK in 2016 was 24%, Australia in 2016 was 22%, Uruguay in 2014 was 19%, and among low income countries, Malaysia in 2013 was 70%, Zambia in 2014 was 57%, Thailand in 2012 was 54%, Mexico from 2014 to 2015 was 38%, Bangladesh from 2014 to 2015 was 37%, Brazil from 2012 to 2013 was 22%, and China from 2013 to 2015 was 15%, for the percentage of respondents of adult smokers believing e-cigarette use is just as risky or more risky to health than cigarettes.[357]
A 2016 review found that "The vaping communities' apparent lack of acknowledgment of the potential negative impacts of e-cigarettes appears to have discredited them in the eyes of many public health officials. Continuing down this path may generate beliefs that the vaping community cares little for public health, are primarily interested in selling their fast-growing companies to the highest tobacco company bidder, and will oppose any meaningful regulations of their product, however reasonable and necessary they may be—essentially aligning the vaping community's practices to tobacco companies' well-established playbook."[358] A 2017 review found that "Although it was originally argued that e‐cigarettes are 'harm free,' the present prevailing belief is that they are 'reduced harm' alternatives to conventional cigarettes. This latter notion is still debatable and not supported by conclusive evidence, especially considering the wide variation between e‐cigarette products."[87] E-cigarette advertisements with warnings could strengthen e-cigarette harm perceptions, and lower the likelihood of buying e-cigarettes.[359]
Gallery
See also
- Health effects of tobacco
- Regulation of electronic cigarettes
- Positions of medical organizations on electronic cigarettes
Notes
- ^ The engineering designs, including the kind of the battery, heating temperature of the solution, and the style of heating element and storage for the solution, typically affects the nature, number, and size of particles generated.[3]
- ^ A 2019 review states, "Experts who favor abstinence contend that if ENDS regulations are too lax, the e-cigarette industry will repeat tobacco manufacturer offences including using media to target youth and misleading the public through false safety claims. They point out that ENDS contain harmful chemicals, lack safety oversight, may renormalize smoking behaviors, and if unchecked, could provide a gateway to tobacco. From this perspective, ENDS may compromise existing tobacco control efforts and have a negative public health impact. Conversely, from a harm reduction perspective, advocates argue that ENDS provide a safer alternative to smoking, especially for smokers who do not desire to quit or find it difficult to do so. They are concerned that over-regulation will extinguish the ENDS market and eliminate the potential for a public health benefit."[23]
- ^ All patients have reported using vaping products.[308] The outbreak has raised concern among public health officials, and revived the debate regarding the effects of vaping.[309] This is the first time that vaping products has been linked to an outbreak of lung illness.[309] Except for one confirmed case in Canada,[310] it seems to be occurring only in the US.[309]
Bibliography
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- Stratton, Kathleen; Kwan, Leslie Y.; Eaton, David L. (January 2018). Stratton, Kathleen; Kwan, Leslie Y.; Eaton, David L. (eds.). Public Health Consequences of E-Cigarettes (PDF). )
- "Electronic Nicotine Delivery Systems and Electronic Non-Nicotine Delivery Systems (ENDS/ENNDS)" (PDF). World Health Organization WHO. August 2016. pp. 1–11.
- Wilder, Natalie; Daley, Claire; Sugarman, Jane; Partridge, James (April 2016). "Nicotine without smoke: Tobacco harm reduction". UK: Royal College of Physicians. pp. 1–191.
- McNeill, A; Brose, LS; Calder, R; Hitchman, SC; Hajek, P; McRobbie, H (August 2015). "E-cigarettes: an evidence update" (PDF). UK: Public Health England. pp. 1–113.
- "State Health Officer's Report on E-Cigarettes: A Community Health Threat" (PDF). California Tobacco Control Program. California Department of Public Health. January 2015. pp. 1–21. This article incorporates text from this source, which is in the public domain.
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External links
- Media related to Electronic cigarettes at Wikimedia Commons