text:
E-cigs vs. T-cigs
Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?
Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.
Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.
Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.
UK Electronic Cigarettes and E-LiquidVarious types of e-cigarettes.
Electronic cigarettes or e-cigarettes[note 1] are handheld electronic devices that try to create a feeling like smoking tobacco. They work by heating a liquid to generate an aerosol, commonly called a "vapor", that the user inhales.[2] Using e-cigarettes is sometimes called vaping.[4] The liquid in the e-cigarette, called e-liquid,[5] is usually made of nicotine, propylene glycol, glycerine, and flavorings.[6] Not all e-liquids contain nicotine.[7]
The health risks of e-cigarettes are uncertain.[8][9][10] They are likely safer than tobacco cigarettes,[11][12] but the long-term health effects are not known.[13][14][15][16][17] They can help some smokers quit.[6][18] When used by non-smokers, e-cigarettes can lead to nicotine addiction, and there is concern that children could start smoking after using e-cigarettes.[19] According to some US sources, minors who use e-cigarettes are more likely to smoke later in life.[20][21] Public Health England attributes this link to a liability for the use of both products rather than one resulting in the other.[15][22] So far, no serious adverse effects have been reported in trials.[6] Less serious adverse effects include throat and mouth irritation, vomiting, nausea, and coughing.[23]
E-cigarettes create an aerosol, commonly called vapor,[23][24] generally containing nicotine, flavors, glycerol and propylene glycol.[25] Its exact composition varies.[24] The majority of toxic chemicals found in tobacco smoke are absent in e-cigarette aerosol.[26][27] Those present are mostly below 1% corresponding levels in tobacco smoke.[28][29] The aerosol can contain toxicants and traces of heavy metals at levels permissible in inhalation medicines,[25] and potentially harmful chemicals not found in tobacco smoke at concentrations permissible by workplace safety standards.[28] However, chemical concentrations may exceed the stricter public safety limits.[23]
The modern e-cigarette was invented in 2003 by Chinese pharmacist Hon Lik,[30] and as of 2015 most e-cigarettes are made in China.[31] Since they were first sold in 2004 their global use has risen exponentially.[32] In the United States and the United Kingdom their use is widespread, and some US schoolchildren use them.[33] Reasons for using e-cigarettes involve trying to quit smoking, reduce risk, or save money, though many use them recreationally.[13] A majority of users still smoke tobacco, causing concerns that dual use may "delay or deter quitting".[23] About 60% of UK users are smokers and roughly 40% are ex-smokers, while use among never-smokers is "negligible".[34] Because of overlap with tobacco laws and medical drug policies, e-cigarette legislation is debated in many countries.[35] A European directive in 2016, set limits for liquids and vaporizers, ingredients, and child-proof liquid containers.[36] As of August 2016, the US FDA extended its regulatory power to include e-cigarettes.[37] There are around 500 brands of e-cigarette with global sales in excess of US$7 billion.[38]
Electronic cigarettes are also known as e-cigarettes, e-cigs, EC,[1] electronic nicotine delivery systems (ENDS) or electronic non-nicotine delivery systems (ENNDS),[2] personal vaporizers, or PVs.[3] They are handheld devices, often made to look like conventional cigarettes, and used in a similar way.[2][39] E-liquid[5] or juice are names for the flavored solution that goes inside the e-cigarette.[40] An aerosol, or vapor, is produced by heating the e-liquid.[41] Irish public health discussions refer to NMNDS ("non-medicinal nicotine delivery systems").[42]Aerosol (vapor) exhaled by an e-cigarette user.
Since their introduction to the market in 2004, global usage of e-cigarettes has risen exponentially.[32] By 2013, there were several million users globally.[43] Awareness and use of e-cigarettes greatly increased in a relatively short period of time.[44] However, growth in the US and UK had reportedly slowed in 2015, lowering market forecasts for 2016.[45][46]
Most users have a history of smoking regular cigarettes.[47] At least 52% of smokers or ex-smokers have vaped.[31] Of smokers who have, less than 15% became everyday e-cigarette users.[6] Though e-cigarette use among those who have never smoked is very low, it continues to rise.[48] A survey of e-cigarette users conducted from 2011–2012 found that only 1% of respondents used liquid without nicotine.[49]
Everyday use is common among e-cigarette users.[50] Vapers mostly keep smoking,[23] although many say vaping helps them cut down or quit smoking.[25][47] Most e-cigarette users are middle-aged men who also smoke traditional cigarettes, either to help them quit or for recreational use.[13] E-cigarette use was also rising among women as of 2014.[51] Some young people who have tried an e-cigarette have never smoked tobacco, so ECs can be a starting point for nicotine use.[23] On the other hand, Public Health England found no evidence e-cigarettes increase teen tobacco smoking. They noted tentative evidence that e-cigarettes divert youth away from cigarettes.[12] A 2014 review raised ethical concerns about minors' e-cigarette use and the potential to weaken cigarette smoking reduction efforts.[52]
In the US, as of 2014, 12.6% of adults had used an e-cigarette at least once and approximately 3.7% were still using them.[53] 1.1% of adults were daily users.[54] Non-smokers and former smokers who had quit more than four years earlier were extremely unlikely to be current users.[54] Former smokers who had recently quit were more than four times as likely to be daily users as current smokers.[54] Experimentation was more common among younger adults, but daily users were more likely to be older adults.[54]Play media National Institute on Drug Abuse director Nora Volkow discussing a study that shows teens using e-cigarettes are more likely to start smoking tobacco.[55]
The recent decline in smoking has accompanied a rapid growth in the use of alternative nicotine products among young people and young adults.[56] In the US, vaping among young people exceeded smoking in 2014.[57] As of 2014, up to 13% of American high school students have used them.[33] Between 2013 and 2014, vaping among students tripled.[58] In 2013 the Centers for Disease Control and Prevention (CDC) estimated that around 160,000 students between 2011 and 2012 who had tried vaping had never smoked.[56] E-cigarette use among never-smoking youth in the US correlates with elevated desires to use traditional cigarettes.[8] Teenagers who had used an e-cigarette were more inclined to become smokers than those who had not.[59] In the 2015 Monitoring the Future survey, a majority of students who used electronic cigarettes reported using liquid without nicotine the last time they vaped.[60] The majority of young people who vape also smoke.[61] A 2010–2011 survey of students at two US high schools found that vapers were more likely to use hookah and blunts than smokers.[62] Among grade 6 to 12 students in the US, the proportion who have tried them rose from 3.3% in 2011 to 6.8% in 2012.[47] Those still vaping over the last month rose from 1.1% to 2.1% and dual use rose from 0.8% to 1.6%.[47] Over the same period, the proportion of grade-6-to-12 students who regularly smoke tobacco fell from 7.5% to 6.7%.[63]
In the UK, user numbers have increased from 700,000 in 2012 to 2.6 million in 2015, but use by current smokers remained flat at 17.6% from 2014 into 2015 (in 2010, it was 2.7%).[34] About one in 20 adults in the UK uses e-cigarettes.[64] In the UK in 2015, 18% of regular smokers said they used e-cigarettes and 59% said they had used them in the past.[34] Among those who had never smoked, 1.1% said they had tried them and 0.2% still use them.[65] In 2013, among those under 18, 7% have used e-cigarettes at least once.[65] Among non-smokers' children, 1% reported having tried e-cigarettes "once or twice", and there was no evidence of continued use.[65] About 60% of all users are smokers and most of the rest are ex-smokers, with "negligible" numbers of never-smokers.[66] In 2015 figures showed around 2% monthly EC-usage among under-18s, and 0.5% weekly, and despite experimentation, "nearly all those using EC regularly were cigarette smokers".[67] 10–11-year-old Welsh never-smokers are more likely to use e-cigarettes if a parent used e-cigarettes.[68]
In France in 2014, between 7.7 and 9.2 million people have tried e-cigarettes and 1.1 to 1.9 million use them on a daily basis.[69] 67% of French smokers use e-cigarettes to reduce or quit smoking. Of French people who have tried e-cigarettes, 9% have never smoked tobacco.[69] Of the 1.2% who had recently stopped tobacco smoking at the time of the survey, 84% (or 1% of the population surveyed) credited e-cigarettes as essential in quitting.[69]
The frequency of vaping in youth is low.[70] Minors who use one tobacco product such as e-cigarettes are more likely to later use other tobacco products such as cigarettes,[20] which likely arises from a common liability for the use of both products.[15] Young people who vape but do not smoke are more likely to try smoking than their peers who do not vape.[71]E-cigarettes often have a high-tech look.[72] Candy, fruit and coffee flavored e-liquid.[73]
Reasons for e-cigarette use often relate to quitting smoking and recreation.[13][50][74] Many users believe vaping is healthier than smoking, although some are concerned about possible adverse health effects.[50] Some use them to circumvent smoke-free laws and policies, or to cut back on cigarette smoking.[23] 56% of respondents in a US 2013 survey had tried vaping to quit or reduce their smoking.[9] In the same survey, 26% of respondents would use them in areas where smoking was banned.[9] Not having odor from smoke on clothes on some occasions prompted interest in or use of e-cigarettes.[50] Many e-cigarette users use them because they believe they are safer than conventional cigarettes.[74]
Non-smoking adults tried e-cigarettes due to curiosity, because a relative was using them, or because they were given one.[62] College students often vape for experimentation.[75] Expensive marketing aimed at smokers suggests e-cigarettes are "newer, healthier, cheaper and easier to use in smoke-free situations, all reasons that e-cigarette users claim motivate their use".[76] Exposure to e-cigarette advertising influenced people to try them.[59]
Some researchers are concerned about vaping during pregnancy.[8][77] E-cigarettes feel or taste similar to traditional cigarettes, and vapers disagreed about whether this was a benefit or a drawback.[50] The majority of committed e-cigarette users interviewed at an e-cigarette convention found them cheaper than traditional cigarettes.[50]
Some users stopped vaping due to issues with the devices.[50] Dissatisfaction and concerns over safety can discourage ongoing e-cigarette use.[64] Some surveys found that a small percentage of users' motives were to avoid smoking bans, but other surveys found that over 40% of users said they used the device for this reason.[50]
The health and lifestyle appeal may also encourage young non-smokers to use e-cigarettes, as they may perceive that trying e-cigarettes is less risky and more socially appealing. This may decrease negative beliefs or concerns about nicotine addiction.[73] Marketing might appeal to young people as well as adults.[78] Adolescent experimenting with e-cigarettes may be sensation seeking behavior, and is not likely to be associated with tobacco reduction or quitting smoking.[8] Young people may view e-cigarettes as a symbol of rebellion.[48] The main reasons young people experimented with e-cigarettes were due to curiosity, flavors, and peer influences.[79] The National Association of County and City Health Officials say there is concern that e-cigarettes may appeal to youth because of their high-tech design, assortment of flavors, and accessibility online.[72] The Heart and Stroke Foundation claims that candy and fruit flavored e-cigarettes are designed to appeal to young people.[80] Infants and toddlers could ingest the e-liquid from an e-cigarette device out of curiosity.[81]
Users may begin by trying a disposable e-cigarette.[70] Users often start with e-cigarettes resembling normal cigarettes, eventually moving to a later-generation device.[82] Most later-generation e-cigarette users shifted to their present device to get a "more satisfying hit",[82] and users may adjust their devices to provide more vapor for better "throat hits".[83]Special e-liquid mixes with THC or other cannabinoids are sold.[84]
The emergence of e-cigs has given cannabis smokers a new method of inhaling cannabinoids.[84] E-cigs differ from traditional marijuana cigarettes in several respects.[84] It is assumed that vaporizing cannabinoids at lower temperatures is safer because it produces smaller amounts of toxic substances than the hot combustion of a marijuana cigarette.[84] Recreational cannabis users can discreetly "vape" deodorized cannabis extracts with minimal annoyance to the people around them and less chance of detection, known as "stealth vaping".[84] While cannabis is not readily soluble in the liquid used for e-cigs, recipes containing synthetic cannabinoids which are soluble may be found on the Internet.[84]
E-cigarettes may be used with other substances and cartridges can potentially be filled with e-liquid containing substances other than nicotine, thus serving as a new and potentially dangerous way to deliver other psychoactive drugs,[85] for example THC.[84]
Cannabinoid-enriched e-liquids require lengthy, complex processing. Some are available on the Internet despite lack of quality control, expiry date, conditions of preservation, or any toxicological and clinical assessment.[84] The health consequences of vaping cannabis preparations are largely unknown.[84]Exploded view of electronic cigarette with transparent clearomizer and changeable dual-coil head. This model allows for a wide range of settings.[86] Electronic cigarettes can come in very different forms—such as this hand-grenade-shaped variant.
The main components of an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[87] The only exception to this are mechanical e-cigarettes (mods) which contain no electronics; the circuit is closed by a mechanical action switch.[88] An atomizer comprises a small heating element, or coil, that vaporizes e-liquid and wicking material that draws liquid onto the coil.[89] When the user pushes a button,[75] or (in some variations) activates a pressure sensor by inhaling, the heating element atomizes the liquid solution.[13] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor,[90] which the user then inhales, rather than cigarette smoke.[24] The aerosol provides a flavor and feel similar to tobacco smoking.[91]
There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[92] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[93] Most cigalikes look like cigarettes but there is some variation in size.[94] A traditional cigarette is smooth and light while a cigalike is rigid and slightly heavier.[91] Second generation devices are larger overall and look less like tobacco cigarettes.[95] Third generation devices include mechanical mods and variable voltage devices.[93] The fourth generation includes Sub ohm tanks and temperature control devices.[96] The power source is the biggest component of an e-cigarette,[32] which is frequently a rechargeable lithium-ion battery.[97]
E-liquid is the mixture used in vapor products such as e-cigarettes[98] and generally consists of propylene glycol, glycerin, water, nicotine, and flavorings.[18] While the ingredients vary[6][70][98] the liquid typically contains 95% propylene glycol and glycerin.[99] There are many e-liquids manufacturers in the USA and worldwide,[100] and upwards of 8,000 flavors.[38] While there are currently no US Food and Drug Administration (FDA) manufacturing standards for e-liquid, the FDA has proposed regulations that were expected to be finalized in late 2015.[100][needs update] Industry standards have been created and published by the American E-liquid Manufacturing Standards Association (AEMSA).[101]Main article: Positions of medical organizations on electronic cigarettes 2014 Centers for Disease Control (CDC) press release about e-cigarettes.[102]
Medical organizations differ about the health implications of vaping.[103] Many medical organizations have made statements about their health and safety. There is general agreement that e-cigarettes expose users to fewer toxicants than tobacco.[6][103] International organizations have hesitated to recommend e-cigarettes for quitting smoking, because of limited evidence of effectiveness and safety.[19][44][104] Some from the UK have recommended their use by smokers unwilling or unable to quit.[105][106]
In August 2016, a World Health Organization (WHO) report found "there is not enough research to quantify the relative risk of ENDS/ENNDS over combustible products. Therefore, no specific figure about how much 'safer' the use of these products is compared to smoking can be given any scientific credibility at this time."[107] In July 2014, a WHO report found limited evidence that e-cigarettes may help some smokers quit, but did not reach conclusions.[19] Smokers should be encouraged to use approved methods for help with quitting,[19] although e-cigarettes may have a role in helping those who have failed to quit by other means.[19] Smokers will get the maximum health benefit if they completely quit all nicotine use.[19] A policy briefing by the Framework Convention Alliance notes widespread agreement that e-cigarettes are "almost certainly considerably less hazardous for individuals than cigarettes", but also notes widespread disagreement on the likelihood and impact of dual use, uptake by never-smokers, and re-normalisation of smoking.[103] The World Lung Foundation has applauded the WHO report's recommendation of tighter regulation due to safety concerns and the risk of increased nicotine addiction or tobacco use among young people.[108]
In a 2015 joint statement, Public Health England and twelve other UK medical bodies concluded "e-cigarettes are significantly less harmful than smoking".[29] PHE also stated that e-cigarettes are estimated to be 95% less harmful than smoking.[109] The UK National Health Service believes that e-cigarettes have about 5% of the risk of tobacco cigarettes,[110] but also feels there will not be a complete understanding of their safety for many years.[110] There are clinical trials in progress to test the quality, safety and effectiveness of e-cigarettes, but until these are complete the NHS maintains that the government could not give any advice on them or to recommend their use.[111] In 2016, the Royal College of Physicians called to "promote e-cigarettes widely as substitute for smoking", concluding that "e-cigarettes are likely to be beneficial to UK public health".[15][112]The United States Centers for Disease Control and Prevention released a 2016 report titled E-cigarette Ads and Youth which concerned marketing towards adolescents.[113]
In 2016, the FDA stated its position that e-cigarettes are "likely less hazardous for an individual user than continued smoking of traditional cigarettes", but that the net population effect is unknown.[16] In 2015, the United States Preventive Services Task Force concluded there is insufficient evidence to recommend e-cigarettes for smoking cessation, and recommended clinicians instead recommend more proven smoking cessation aids.[114] The National Institute on Drug Abuse raises concern over the possibility that they could perpetuate nicotine addiction and thus interfere with quitting.[115] In 2015, the American Academy of Pediatrics strongly recommended against using e-cigarettes to quit smoking, stating that for adolescents e-cigarettes are not effective in treating tobacco dependence.[116] In August 2014, the American Heart Association released a policy statement concluding that while e-cigarette aerosol is much less toxic then cigarette smoke, there is insufficient evidence for clinicians to counsel smokers to use them as a primary cessation aid. If a patient failed initial treatment or refuses to use cessation medication, and wishes to use e-cigarettes to quit, it is reasonable to support the attempt after informing about the uncertainties.[117] In 2014, the US FDA said "E-cigarettes have not been fully studied, so consumers currently don't know: the potential risks of e-cigarettes when used as intended, how much nicotine or other potentially harmful chemicals are being inhaled during use, or whether there are any benefits associated with using these products. Additionally, it is not known whether e-cigarettes may lead young people to try other tobacco products, including conventional cigarettes, which are known to cause disease and lead to premature death."[104]Play media CDC launches "Tips From Former Smokers" ad campaign in 2015. The main information on e-cigarettes begins at 24:45.[118]
The available research on e-cigarette use for smoking cessation is limited to three randomized controlled trials and some user surveys, case reports, and cohort studies.[119] Some consider the evidence contradictory,[9][117] while others attribute negative outcomes to inappropriate study design.[6][105][120] Some medical authorities recommend that e-cigarettes have a role in smoking cessation, and others disagree. On the one hand, Public Health England recommends that stop-smoking practitioners should (1) advise people who want to quit to try e-cigarettes if they are failing with conventional nicotine replacement therapy (NRT); and (2) advise people who cannot or do not want to quit to switch to e-cigarettes.[29] On the other hand, the United States Preventive Services Task Force advised only use of conventional NRT products in smoking cessation and found insufficient evidence to recommend e-cigarettes for this purpose.[9]
There is tentative evidence that they can help people quit smoking,[6] but studies pertaining to their potential impact on smoking cessation and reduction is very limited.[121] However, a 2016 meta-analysis based on 20 different studies found that smokers who used electronic cigarettes were 28% less likely to quit than those who had not tried electronic cigarettes.[122] This finding persisted whether the smokers were initially interested in quitting or not.[122] A 2015 meta-analysis on clinical trials found that nicotine-containing e-liquids are more effective than nicotine-free ones for quitting smoking. They compared their finding that nicotine-containing e-cigarettes helped 20% of people quit with the results from other studies that found conventional NRT helps 10% of people quit.[123] There has only been one study directly comparing first generation e-cigarettes to conventional NRT as smoking cessation tools, so the comparative effectiveness is not known.[123] Two 2016 reviews found a trend towards benefit of e-cigarettes with nicotine for smoking cessation, but that the evidence was of low quality.[124][125] Another 2016 review found that the combined abstinence rate among smokers using e-cigarettes in prospective studies was 29.1%. The same review noted that few clinical trials had yet been conducted on their effectiveness, and only one had included a group using other cessation methods.[126]
However, e-cigarettes have not been subject to the same efficacy testing as nicotine replacement products. Several authorities, including the World Health Organisation, take the view that there is not enough evidence to recommend e-cigarettes for quitting smoking in adults,[9] and there are studies showing a decline in smoking cessation among dual users.[122] A 2014 review found that e-cigarettes do not seem to improve cessation rates compared to regulated nicotine replacement products, and a trial found 29% of e-cigarette users were still vaping at 6 months, but only 8% of patch users still wore patches at 6 months.[47] There is low-quality evidence that vaping assists smokers to quit smoking in the long-term compared with nicotine-free vaping.[127] Nicotine-containing e-cigarettes were associated with greater effectiveness for quitting smoking than e-cigarettes without nicotine.[123] E-cigarettes without nicotine may reduce tobacco cravings because of the smoking-related physical stimuli.[128]
Tobacco harm reduction (THR) is replacing tobacco cigarettes with lower risk products to reduce death and disease.[129] THR has been controversial out of fear that tobacco companies cannot be trusted to make products that will reduce this risk.[128] E-cigarettes can reduce smokers' exposure to carcinogens and other toxic substances found in tobacco.[128][130]
Tobacco smoke contains 100 known carcinogens, and 900 potentially cancer causing chemicals,[98] none of which has been found in more than trace quantities in e-cigarette vapor.[128] While e-cigarettes cannot be considered "safe" because there is no safe level for carcinogens, they are doubtless safer than tobacco cigarettes.[128] E-cigarettes are not dangerous enough to warrant serious public health concerns given the known risks of conventional cigarettes. The same review concluded that evidence supported "the cautionary implementation of harm reduction interventions aimed at promoting e-cigarettes as attractive and competitive alternatives to cigarette smoking", provided efforts were also made to protect vulnerable groups from e-cigarettes.[131]
A core concern is that smokers who could have quit completely will develop an alternative nicotine addiction instead.[128] A 2014 review stated that promotion of vaping as a harm reduction aid is premature,[132] but they could help to lower tobacco-related death and disease if examined more thoroughly.[18] Another review found that compared with cigarettes, e-cigarettes are likely to be much less, if at all, harmful to users or bystanders.[25] The authors warned against the potential harm of excessive regulation and advised health professionals to consider advising smokers who are reluctant to quit by other methods to switch to e-cigarettes as a safer alternative to smoking.[25] A 2015 Public Health England report concluded that e-cigarette use "releases negligible levels of nicotine into ambient air with no identified health risks to bystanders".[133] A 2014 review recommended that regulations for e-cigarettes could be similar to those for dietary supplements or cosmetic products to not limit their potential for harm reduction.[134] A 2012 review found e-cigarettes could considerably reduce traditional cigarettes use and they likely could be used as a lower risk replacement for traditional cigarettes, but there is not enough data on their safety and efficacy to draw definite conclusions.[91] E-cigarette use for risk reduction in high-risk groups such as people with mental disorders is unavailable.[135]
Hazards associated with products currently on the market are probably low, and certainly much lower than smoking. However, harms could be reduced further through appropriate product standards.[26] Many smokers want to reduce harm from smoking by using these products.[26] The British Medical Association encourages health professionals to recommend conventional nicotine replacement therapies, but for patients unwilling to use or continue using such methods, health professionals may present e-cigarettes as a lower-risk option than tobacco smoking.[136] The American Association of Public Health Physicians (AAPHP) suggests those who are unwilling to quit tobacco smoking or unable to quit with medical advice and pharmaceutical methods should consider other nicotine containing products such as electronic cigarettes and smokeless tobacco for long term use instead of smoking.[137] In an interview, the director of the Office on Smoking and Health for the U.S. federal agency Centers for Disease Control and Prevention (CDC) believes that there is enough evidence to say that using e-cigarettes is likely less harmful than smoking a pack of conventional cigarettes.[138] However, due to the lack of regulation of the contents of e-cigarettes and the presence of nicotine, the CDC has issued warnings.[138] A 2014 WHO report concluded that some smokers will switch completely to e-cigarettes from traditional tobacco but a "sizeable" number will use both.[19] This report found that such "dual use" of e-cigarettes and tobacco "will have much smaller beneficial effects on overall survival compared with quitting smoking completely."[19]Main articles: Safety of electronic cigarettes and Electronic cigarette aerosol and e-liquid Adverse effects of vaping.[139]
The safety of electronic cigarettes is uncertain.[8][9][10] However, they are likely substantially safer than tobacco cigarettes.[6][117][140] There is considerable variation between vaporizers and in quality of their liquid ingredients and thus the contents of the vapor.[23][141][142] Reviews on the safety of electronic cigarettes, analyzing almost the same studies, resulted in substantially different conclusions.[143] In July 2014 the World Health Organization (WHO) report cautioned about potential risks of using e-cigarettes.[19] Regulated US Food and Drug Administration (FDA) products such as nicotine inhalers are probably safer than e-cigarettes.[132] In 2015, Public Health England stated that e-cigarettes are estimated to be 95% less harmful than smoking.[109] A 2014 systematic review concluded that the risks of e-cigarettes have been exaggerated by health authorities and stated that while there may be some remaining risk, the risk of e-cigarette use is likely small compared to smoking tobacco.[27]
The long-term effects of e-cigarette use are unknown.[75][13][127] Improvements in lung function and pulmonary health have been demonstrated among smokers who have switched to e-cigarettes.[144][145] A 2014 Cochrane review found no serious adverse effects reported in clinical trials.[6] Less serious adverse effects from e-cigarette use include throat and mouth irritation, vomiting, nausea, and cough.[23] The evidence suggests they produce less harmful effects than tobacco.[146] A 2014 WHO report said, "ENDS use poses serious threats to adolescents and fetuses."[19] Aside from toxicity, there are also risks from misuse or accidents[27] such as contact with liquid nicotine,[147] fires caused by vaporizer malfunction,[23] and explosions as result from extended charging, unsuitable chargers, or design flaws.[27] Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.[8] There is a small risk of battery explosion in devices modified to increase battery power.[90]
The e-liquid has a low level of toxicity, but contamination with various chemicals has been found.[148] The majority of toxic chemicals found in tobacco smoke are absent in e-cigarette vapor.[26][27] Those which are present are mostly below 1% of the corresponding levels in tobacco smoke, and far below safety limits for occupational exposure.[28][149] Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.[27] Normal usage of e-cigarettes generates very low levels of formaldehyde.[150] A 2015 review found that later-generation e-cigarettes set at higher power may generate equal or higher levels of formaldehyde compared to smoking.[75][151] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[150] The 2015 Public Health England report looking at the research concluded 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.[12] Users detect the "dry puff" and avoid it, and the report concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[12] E-cigarette users who use e-cigarettes that contain nicotine are exposed to its potentially harmful effects.[24] Nicotine is associated with cardiovascular disease, potential birth defects, and poisoning.[152]In vitro studies of nicotine have associated it with cancer, but carcinogenicity has not been demonstrated in vivo.[152] There is inadequate research to demonstrate that nicotine is associated with cancer in humans.[153] The risk is probably low from the inhalation of propylene glycol and glycerin.[25] No information is available on the long-term effects of the inhalation of flavors.[148] Most of the cardiovascular effects of ECs are consistent with those of nicotine. According to a 2017 review, it is possible that ECs may have adverse cardiovascular effects on users, especially those who already have cardiovascular disease. However, this review also concluded that "the risk is thought to be less than that of cigarette smoking based on qualitative and quantitative comparisons of EC aerosol versus cigarette smoke constituents."[154]
E-cigarettes create vapor that consists of ultrafine particles, with the majority of particles in the ultrafine range.[23] The vapor has been found to contain flavors, propylene glycol, glycerin, nicotine, tiny amounts of toxicants, carcinogens, heavy metals, and metal nanoparticles, and other chemicals.[23][25] Exactly what comprises the vapor varies in composition and concentration across and within manufacturers.[24] However, e-cigarettes cannot be regarded as simply harmless.[155] There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors.[32] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[77] A 2014 review recommended that e-cigarettes should be regulated for consumer safety.[134] There is limited information available on the environmental issues around production, use, and disposal of e-cigarettes that use cartridges.[156] A 2014 review found "disposable e-cigarettes might cause an electrical waste problem."[135]
The World Health Organization has concluded regarding second hand aerosol (SHA) "that while there are a limited number of studies in this area, it can be concluded that SHA is a new air contamination source for particulate matter, which includes fine and ultrafine particles, as well as 1,2-propanediol, some VOCs [volatile organic compounds], some heavy metals, and nicotine" and "[i]t is nevertheless reasonable to assume that the increased concentration of toxicants from SHA over background levels poses an increased risk for the health of all bystanders".[107] Public Health England has concluded that "international peer-reviewed evidence indicates that the risk to the health of bystanders from secondhand e-cigarette vapour is extremely low and insufficient to justify prohibiting e-cigarettes".[157] A systematic review concluded, "the absolute impact from passive exposure to EC [electronic cigarette] vapour has the potential to lead to adverse health effects. The risk from being passively exposed to EC vapour is likely to be less than the risk from passive exposure to conventional cigarette smoke."[158]
Nicotine, a key ingredient in e-liquids, is a highly addictive substance, on a level comparable to heroin and cocaine.[159] Nicotine stimulates regions of the cortex associated with reward, pleasure and reducing anxiety.[90] When nicotine intake stops, withdrawal symptoms include cravings for nicotine, anger/irritability, anxiety, depression, impatience, trouble sleeping, restlessness, hunger or weight gain, and difficulty concentrating.[48][160] It is not clear whether e-cigarette use will decrease or increase overall nicotine addiction,[161] but the nicotine content in e-cigarettes is adequate to sustain nicotine dependence.[162]
The World Health Organization is concerned about addiction for non-smokers,[19] and the National Institute on Drug Abuse said e-cigarettes could maintain nicotine addiction in those who are attempting to quit.[163] The limited available data suggests that the likelihood of abuse from e-cigarettes is smaller than traditional cigarettes.[164] A 2014 systematic review found that the concerns that e-cigarettes could lead non-smokers to start smoking are unsubstantiated.[27] No long-term studies have been done on the effectiveness of e-cigarettes in treating tobacco addiction,[132] but some evidence suggests that dual use of e-cigarettes and traditional cigarettes may be associated with greater nicotine dependence.[75]
Many studies have focused on young people, since youthful experimentation with e-cigarettes could lead to lifelong addiction.[59] Various organizations, including the UATLD, the AAP and the FDA, have expressed concern that e-cigarette use could increase nicotine addiction in youth.[138][163][165][166][167][168][169] Although regular use of e-cigarettes is generally very low by people who have never smoked,[25] significant numbers of teenagers who have never smoked tobacco have experimented with e-cigarettes.[23] The degree to which teens are using e-cigarettes in ways the manufacturers did not intend, such as increasing the nicotine delivery, is unknown,[147] as is the extent to which e-cigarette use could lead to addiction or substance dependence in youth.[147]
Smoking a traditional cigarette yields between 0.5 and 1.5 mg of nicotine,[162] but the nicotine content of the cigarette is only weakly correlated with the levels of nicotine in the smoker's bloodstream.[170] The amount of nicotine in the e-cigarette aerosol varies widely either from puff-to-puff or among products of the same company.[24] In practice e-cigarette users tend to reach lower blood nicotine concentrations than smokers, particularly when the users are inexperienced or using earlier-generation devices.[93] Nicotine in tobacco smoke is absorbed into the bloodstream rapidly, and e-cigarette vapor is relatively slow in this regard.[93] The concentration of nicotine in e-liquid ranges up to 36 mg/mL.[26] New EU regulations cap this at a maximum of 2% (20 mg/mL), but this is an arbitrary ceiling based on limited data.[8] In practice the nicotine concentration in an e-liquid is not a reliable guide to the amount of nicotine that reaches the bloodstream.[26]
The earliest e-cigarette can be traced to American Herbert A. Gilbert,[171] who in 1963 patented "a smokeless non-tobacco cigarette" that involved "replacing burning tobacco and paper with heated, moist, flavored air".[172][173] This device produced flavored steam without nicotine.[173] The patent was granted in 1965.[174] Gilbert's invention was ahead of its time.[175] There were prototypes, but it received little attention[176] and was never commercialized[173] because smoking was still fashionable at that time.[177] Gilbert said in 2013 that today's electric cigarettes follow the basic design set forth in his original patent.[174]
Hon Lik, a Chinese pharmacist and inventor who worked as a research pharmacist for a company producing ginseng products, is credited with the invention of the modern e-cigarette.[30] Lik quit smoking after his father, also a heavy smoker, died of lung cancer.[30] In 2001, he thought of using a high frequency, piezoelectric ultrasound-emitting element to vaporize a pressurized jet of liquid containing nicotine.[178] This design creates a smoke-like vapor.[30] Lik said that using resistance heating obtained better results and the difficulty was to scale down the device to a small enough size.[178] Lik's invention was intended to be an alternative to smoking.[178]The Ruyan e-cigar was first launched in China in 2004.
Hon Lik registered a patent for the modern e-cigarette design in 2003.[178] The e-cigarette was first introduced to the Chinese domestic market in 2004.[30] Many versions made their way to the U.S., sold mostly over the Internet by small marketing firms.[30] E-cigarettes entered the European market and the US market in 2006 and 2007.[50] The company that Lik worked for, Golden Dragon Holdings, registered an international patent in November 2007.[179] The company changed its name to Ruyan (如烟, literally "Resembling smoking") later the same month[180] and started exporting its products.[30] Many US and Chinese e-cig makers copied his designs illegally, so Lik has not received much financial reward for his invention (although some US manufacturers have compensated him through out of court settlements).[181] Ruyan later changed its company name to Dragonite International Limited.[180] Most e-cigarettes today use a battery-powered heating element rather than the earlier ultrasonic technology design.[117]
When e-cigarettes entered the international market, some users were dissatisfied with their performance,[182][183] and the e-cigarette continued to evolve from the first generation three-part device.[94] In 2007 British entrepreneurs Umer and Tariq Sheikh invented the cartomizer.[184] This is a mechanism that integrates the heating coil into the liquid chamber.[184] They launched this new device in the UK in 2008 under their Gamucci brand,[183] and the design is now widely adopted by most "cigalike" brands.[94] Other users tinkered with various parts to produce more satisfactory homemade devices, and the hobby of "modding" was born.[182] The first mod to replace the e-cigarette's case to accommodate a longer-lasting battery, dubbed the "screwdriver", was developed by Ted and Matt Rogers[182] in 2008.[97] Other enthusiasts built their own mods to improve functionality or aesthetics.[182] When pictures of mods appeared at online vaping forums many people wanted them, so some mod makers produced more for sale.[182]
The demand for customizable e-cigarettes prompted some manufacturers to produce devices with interchangeable components that could be selected by the user.[97] In 2009, Joyetech developed the eGo series[184] which offered the power of the screwdriver model and a user-activated switch to a wide market.[97] The clearomizer was invented in 2009.[184] Originating from the cartomizer design, it contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component.[184] The clearomizer allows the user to monitor the liquid level in the device.[184] Soon after the clearomizer reached the market, replaceable atomizer coils and variable voltage batteries were introduced.[184] Clearomizers and eGo batteries became the best-selling customizable e-cigarette components in early 2012.[97]
International tobacco companies dismissed e-cigarettes as a fad at first.[185] However, recognizing the development of a potential new market sector that could render traditional tobacco products obsolete,[186] they began to produce and market their own brands of e-cigarettes and acquire existing e-cigarette companies.[187]blu eCigs, a prominent US e-cigarette manufacturer, was acquired by Lorillard Inc. in 2012.[188]British American Tobacco was the first tobacco business to sell e-cigarettes in the UK.[189] They launched Vype in 2013, while Imperial Tobacco's Fontem Ventures acquired the intellectual property owned by Hon Lik through Dragonite International Limited for $US 75 million in 2013 and launched Puritane in partnership with Boots UK.[190] On 1 October 2013 Lorillard Inc. acquired another e-cigarette company, this time the UK based company SKYCIG.[191] SKY was rebranded as blu.[192] On 3 February 2014, Altria Group, Inc. acquired popular electronic cigarette brand Green Smoke for $110 million.[193] The deal was finalized in April 2014 for $110 million with $20 million in incentive payments.[193] Altria also markets its own e-cigarette, the MarkTen, while Reynolds American has entered the sector with its Vuse product.[187] Philip Morris, the world's largest tobacco firm, purchased UK's Nicocigs in June 2014.[194] On 30 April 2015, Japan Tobacco bought the US Logic e-cigarette brand.[195] Japan Tobacco also bought the UK E-Lites brand in June 2014.[195] On 15 July 2014, Lorillard sold blu to Imperial Tobacco as part of a deal for $7.1 billion.[196]
In 2014, dollar sales of customizable e-cigarettes and e-liquid surpassed sales of cigalikes in the US, despite the fact that customizables are less expensive.[197]
Consumers of e-cigarettes, sometimes called "vapers", have shown passionate support for e-cigarettes that other nicotine replacement therapies did not receive.[26][198] This suggests e-cigarettes have potential mass appeal that could challenge combustible tobacco's market position.[26]
A subculture of "vapers" has emerged.[198][199] Members of this emerging subculture often see e-cigarettes as a safer alternative to smoking,[25] and some view it as a hobby.[200] The online forum Electronic Cigarette Forum was one of the first major communities.[182] It and other online forums, such as UKVaper.org, were the origins of the hobby of modding.[182] There are also groups on Facebook and Reddit.[201] Online forums based around modding have grown in the vaping community.[202] Vapers energetically embrace activities associated with e-cigarettes and sometimes act as unpaid evangelists according to a 2014 review.[83] A 2014 Postgraduate Medical Journal editorial stated that e-cigarette companies have a substantial online presence, as well as many individual vapers who blog and tweet about e-cigarette related products.[203] The editorial stated that vapers "also engage in grossly offensive online attacks on anyone who has the temerity to suggest that ENDS are anything other than an innovation that can save thousands of lives with no risks".[203] A 2014 review stated that tobacco and e-cigarette companies interact with consumers for their policy agenda.[23] The companies use websites, social media, and marketing to get consumers involved in opposing bills that include e-cigarettes in smoke-free laws.[23] The same review said this is similar to tobacco industry activity going back to the 1980s.[23] These approaches were used in Europe to minimize the EU Tobacco Product Directive in October 2013.[23] True grassroots lobbying also influenced the TPD decision.[204]Rebecca Taylor, a member of the European Parliament, stated, "to say it's an orchestrated campaign is absolute rubbish."[204] Contempt for "big tobacco" is part of vaping culture.[205][206]E-cigarette user blowing a cloud of aerosol (vapor). The activity is known as cloud-chasing.[207]
Large gatherings of vapers, called vape meets, take place around the US.[198] They focus on e-cig devices, accessories, and the lifestyle that accompanies them.[198] Vapefest, which started in 2010, is an annual show hosted by different cities.[201] People attending these meetings are usually enthusiasts that use specialized, community-made products not found in convenience stores or gas stations.[198] These products are mostly available online or in dedicated "vape" storefronts where mainstream e-cigarettes brands from the tobacco industry and larger e-cig manufacturers are not as popular.[208] Some vape shops have a vape bar where patrons can test out different e-liquids and socialize.[209] The Electronic Cigarette Convention in North America which started in 2013, is an annual show where companies and consumers meet up.[210]
A subclass of vapers configure their atomizers to produce large amounts of vapor by using low-resistance heating coils.[211] This practice is called "cloud-chasing"[212][213] By using a coil with very low resistance, the batteries are stressed to a potentially unsafe extent.[212] This could present a risk of dangerous battery failures.[212] As vaping comes under increased scrutiny, some members of the vaping community have voiced their concerns about cloud-chasing, claiming the practice gives vapers a bad reputation when doing it in public.[214] The Oxford Dictionaries' word of the year for 2014 was "vape".[215]Main articles: Regulation of electronic cigarettes and List of vaping bans in the United States A no smoking or vaping sign from the US.
Regulation of e-cigarettes varies across countries and states, ranging from no regulation to banning them entirely.[216] Others have introduced strict restrictions and some have licensed devices as medicines such as in the UK.[217] As of 2015[update], around two thirds of major nations have regulated e-cigarettes in some way.[218] Because of the potential relationship with tobacco laws and medical drug policies, e-cigarette legislation is being debated in many countries.[35] The companies that make e-cigarettes have been pushing for laws that support their interests.[219] In 2016 the US Department of Transportation banned the use of e-cigarettes on commercial flights.[220] This regulation applies to all flights to and from the US.[220]
The legal status of e-cigarettes is currently pending in many countries.[23] Many countries such as Brazil, Singapore, the Seychelles, Uruguay, and Norway have banned e-cigarettes.[217] In Canada, they are technically illegal to sell, as no nicotine-containing e-fluid is approved by Health Canada, but this is generally unenforced and they are commonly available for sale Canada-wide.[221] In the US and the UK, the use and sale to adults of e-cigarettes are legal.[222]:US[223]:UK As of August 8, 2016, the FDA extended its regulatory power to include e-cigarettes.[37] Under this ruling the FDA will evaluate certain issues, including ingredients, product features and health risks, as well their appeal to minors and non-users.[224] The FDA rule also bans access to minors.[224] A photo ID is required to buy e-cigarettes,[225] and their sale in all-ages vending machines is not permitted.[224] In May 2016 the FDA used its authority under the Family Smoking Prevention and Tobacco Control Act to deem e-cigarette devices and e-liquids to be tobacco products, which meant it intended to regulate the marketing, labelling, and manufacture of devices and liquids; vape shops that mix e-liquids or make or modify devices were considered manufacturing sites that needed to register with FDA and comply with good manufacturing practice regulation.[16] E-cigarette and tobacco companies have recruited lobbyists in an effort to prevent the FDA from evaluating e-cigarette products or banning existing products already on the market.[226]
In February 2014 the European Parliament passed regulations requiring standardization and quality control for liquids and vaporizers, disclosure of ingredients in liquids, and child-proofing and tamper-proofing for liquid packaging.[36][227] In April 2014 the FDA published proposed regulations for e-cigarettes along similar lines.[228][229] In the US some states tax e-cigarettes as tobacco products, and some state and regional governments have broadened their indoor smoking bans to include e-cigarettes.[76] As of 9 October 2015, at least 48 states and 2 territories banned e-cigarette sales to minors.[230]
E-cigarettes have been listed as drug delivery devices in several countries because they contain nicotine, and their advertising has been restricted until safety and efficacy clinical trials are conclusive.[231] Since they do not contain tobacco, television advertising in the US is not restricted.[232] Some countries have regulated e-cigarettes as a medical product even though they have not approved them as a smoking cessation aid.[233] A 2014 review stated the emerging phenomenon of e-cigarettes has raised concerns in the health community, governments, and the general public and recommended that e-cigarettes should be regulated to protect consumers.[134] It added, "heavy regulation by restricting access to e-cigarettes would just encourage continuing use of much unhealthier tobacco smoking."[134] A 2014 review said these products should be considered for regulation in view of the "reported adverse health effects".[233]
A 2014 review said, "the e-cigarette companies have been rapidly expanding using aggressive marketing messages similar to those used to promote cigarettes in the 1950s and 1960s."[23] E-cigarettes and nicotine are regularly promoted as safe and beneficial in the media and on brand websites.[77] While advertising of tobacco products is banned in most countries, television and radio e-cigarette advertising in some countries may be indirectly encouraging traditional cigarette smoking.[23] There is no evidence that the cigarette brands are selling e-cigarettes as part of a plan to phase out traditional cigarettes, despite some claiming to want to cooperate in "harm reduction".[23] In the US, six large e-cigarette businesses spent $59.3 million on promoting e-cigarettes in 2013.[234] Easily circumvented age verification at company websites enables young people to access and be exposed to marketing for e-cigarettes.[73]
A national US television advertising campaign starred Steven Dorff exhaling a "thick flume" of what the ad describes as "vapor, not tobacco smoke", exhorting smokers with the message "We are all adults here, it's time to take our freedom back."[235] The ads, in a context of longstanding prohibition of tobacco advertising on TV, were criticized by organizations such as Campaign for Tobacco-Free Kids as undermining anti-tobacco efforts.[235] Cynthia Hallett of Americans for Non-Smokers' Rights described the US advertising campaign as attempting to "re-establish a norm that smoking is okay, that smoking is glamorous and acceptable".[235] University of Pennsylvania communications professor Joseph Cappella stated that the setting of the ad near an ocean was meant to suggest an association of clean air with the nicotine product.[235] In 2012 and 2013, e-cigarette companies advertised to a large television audience in the US which included 24 million youth.[236] The channels on which e-cigarette advertising reached the largest numbers of youth (ages 12–17) were AMC, Country Music Television, Comedy Central, WGN America, TV Land, and VH1.[236]
A 2014 review said e-cigarettes are aggressively promoted, mostly via the internet, as a healthy alternative to smoking in the US.[32]Celebrity endorsements are used to encourage e-cigarette use.[78] "Big tobacco" markets e-cigarettes to young people,[237] with industry strategies including cartoon characters and candy flavors to sell e-cigarettes.[238] E-cigarette companies commonly promote that their products contain only water, nicotine, glycerin, propylene glycol, and flavoring but this assertion is misleading as scientists have found differing amounts of heavy metals in the vapor, including chromium, nickel, tin, silver, cadmium, mercury, and aluminum.[57] The assertion that e-cigarette emit "only water vapor" is false because the evidence indicates e-cigarette vapor contains possibly harmful chemicals such as nicotine, carbonyls, metals, and organic volatile compounds, in addition to particulates.[239]Vaping stand, London shopping centre.
The number of e-cigarettes sold increased every year[117] from 2003 to 2015, when a slowdown in the growth in usage occurred in both the US and the UK.[45][46] As of 2014[update] there were at least 466 e-cigarette brands.[49] Worldwide e-cigarette sales in 2014 were around US$7 billion.[240] Approximately 30–50% of total e-cigarettes sales are handled on the internet.[32]
As of 2015[update] most e-cigarette devices were made in China,[31] mainly in Shenzhen.[241][242] Chinese companies' market share of e-liquid is low.[243]
In the US, tobacco producers have a significant share of the e-cigarette market.[59][244] As of 2015[update], 80% of all e-cigarette sales in convenience stores in the U.S. were products made by tobacco companies.[245] According to Nielsen Holdings, convenience store e-cigarette sales in the US went down for the first time during the four-week period ending on 10 May 2014.[246] Wells Fargo analyst Bonnie Herzog attributes this decline to a shift in consumers' behavior, buying more specialized devices or what she calls "vapor/tank/mods (VTMs)" that are not tracked by Nielsen.[246] Wells Fargo estimated that VTMs accounted for 57% of the 3.5 billion dollar market in the US for vapor products in 2015.[247] In 2014, the Smoke-Free Alternatives Trade Association estimated that there were 35,000 vape shops in the US, more than triple the number a year earlier.[248] However the 2015 slowdown in market growth affected VTMs as well.[45]
In Canada, e-cigarettes had an estimated value of 140 million CAD in 2015.[249] There are numerous e-cigarette retail shops in Canada.[250] A 2014 audit of retailers in four Canadian cities found that 94% of grocery stores, convenience stores, and tobacconist shops which sold e-cigarettes sold nicotine-free varieties only, while all vape shops stocked at least one nicotine-containing product.[251]
In the UK in 2015 the "most prominent brands of cigalikes" were owned by tobacco companies, but except for one model all the tank types came from "non-tobacco industry companies".[105] However some tobacco industry products, while using prefilled cartridges, resemble tank models.[105]
France's electronic cigarette market was estimated by Groupe Xerfi to be €130 million in 2015. Additionally, France's e-liquid market was estimated at €265 million.[252] In December 2015, there were 2,400 vape shops in France, 400 fewer than in March of the same year.[252] Industry organization Fivape said the reduction was due to consolidation, not to reduced demand.[252]
Other devices to deliver inhaled nicotine have been developed.[253] They aim to mimic the ritual and behavioral aspects of traditional cigarettes.[253]
British American Tobacco, through their subsidiary Nicoventures, licensed a nicotine delivery system based on existing asthma inhaler technology from UK-based healthcare company Kind Consumer.[254] In September 2014 a product based on this named Voke obtained approval from the United Kingdom's Medicines and Healthcare Products Regulatory Agency.[255]
Philip Morris International (PMI) bought the rights to a nicotine pyruvate technology developed by Jed Rose at Duke University.[256] The technology is based on the chemical reaction between pyruvic acid and nicotine, which produces an inhalable nicotine pyruvate vapor.[257]
PAX Labs has developed vaporizers that heats the leaves of tobacco to deliver nicotine in a vapor.[258][259] On 1 June 2015, they introduced Juul a different type of e-cigarette which delivers 10 times as much nicotine as other e-cigarettes, equivalent to an actual cigarette puff.[260]
BLOW started selling e-hookahs, an electronic version of the hookah, in 2014.[261] Several companies including Canada's Eagle Energy Vapor are selling caffeine-based e-cigarettes instead of nicotine.[262]
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(Redirected from Health effects of electronic cigarettes)
E-cigarette seller destroys €135,000 worth of nicotine liquid - Nicorex! NB - OPEN SUBTITLES! UK
The safety of electronic cigarettes is uncertain.[1][2][3] There is little data about their safety, and considerable variability among e-cigarettes and in their liquid ingredients[4] and thus the contents of the aerosol delivered to the user.[5] Reviews on the safety of e-cigarettes have reached significantly different conclusions.[6] A 2014 World Health Organization (WHO) report cautioned about potential risks of using e-cigarettes.[7] Regulated US Food and Drug Administration (FDA) products such as nicotine inhalers are likely safer than e-cigarettes,.[8] A systematic review suggests that e-cigarettes are less harmful than smoking and since they contain no tobacco and do not involve combustion, users may avoid several harmful constituents usually found in tobacco smoke.[9][10][11] However, e-cigarettes cannot be considered harmless.[12]
E-cigarettes have been found to reduce lung and myocardial function, increase inflammation, and have toxic content including carcinogens, but to a much lower extent than combustible cigarettes in virtually all cases.[3][13] The long-term effects of e-cigarette use are unknown.[13][14][15] A 2015 study found serious adverse events related to e-cigarettes were hypotension, seizure, chest pain, rapid heartbeat, disorientation, and congestive heart failure but it was unclear to the degree they were the result of e-cigarettes.[16] Less serious adverse effects may include abdominal pain, headache, blurry vision,[16] throat and mouth irritation, vomiting, nausea, and coughing.[5] A 2014 WHO report said, "ENDS [electronic nicotine delivery system] use poses serious threats to adolescents and fetuses."[7] Aside from toxicity exposure in normal use, there are also risks from misuse or accidents[9] such as nicotine poisoning (especially among infants and children),[17] contact with liquid nicotine,[18] fires caused by vaporizer malfunction,[5] and explosions resulting from extended charging, unsuitable chargers, or design flaws.[9] Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.[1] There is a small risk of battery explosion in devices modified to increase battery power.[19]
The cytotoxicity of e-liquids varies,[20] and contamination with various chemicals have been detected in the liquid.[21] Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.[9] Many chemicals including carbonyl compounds such as formaldehyde can inadvertently be produced when the nichrome wire (heating element) that touches the e-liquid is heated and chemically reacted with the liquid.[22] Normal usage of e-cigarettes,[23] and reduced voltage (3.0 V[24]) devices generate very low levels of formaldehyde.[22] Later-generation e-cigarettes used with higher power may generate equal or higher levels of formaldehyde than compared to smoking.[14][Notes 1] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[25] A 2015 Public Health England (PHE) report found that high levels of formaldehyde only occurred in overheated "dry-puffing".[26] Users detect the "dry puff" and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[27] However, e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[19] E-cigarette users who use devices that contain nicotine are exposed to its potentially harmful effects.[24] Nicotine is associated with cardiovascular disease, potential birth defects, and poisoning.[28]In vitro studies of nicotine have associated it with cancer, but carcinogenicity has not been demonstrated in vivo.[28] There is inadequate research to demonstrate that nicotine is associated with cancer in humans.[29] The risk is probably low from the inhalation of propylene glycol and glycerin.[13] No information is available on the long-term effects of the inhalation of flavors.[21]
E-cigarettes create an aerosol that consists of fine and ultrafine particles of particulate matter, with the majority of particles in the ultrafine range.[5][30] The vapor have been found to contain flavors, propylene glycol, glycerin, nicotine, tiny amounts of toxicants, carcinogens, heavy metals, and metal nanoparticles, and other substances.[5][13] Exactly what the vapor comprises varies in composition and concentration across and within manufacturers.[24] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[31] The majority of toxic chemicals found in tobacco smoke are absent in e-cigarette vapor.[9] E-cigarette vapor contains lower concentrations of potentially toxic chemicals than with cigarette smoke.[32] Those which are present, are mostly below 1% the corresponding levels permissible by workplace safety standards.[33] But workplace safety standards do not recognize exposure to certain vulnerable groups such as people with medical ailments, children, and infants who may be exposed to second-hand vapor.[5] Concern exists that some of the mainstream vapor exhaled by e-cigarette users may be inhaled by bystanders, particularly indoors.[34] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[35] A 2014 review recommended that e-cigarettes should be regulated for consumer safety.[36] There is limited information available on the environmental issues around production, use, and disposal of e-cigarettes that use cartridges.[37]
Reviews on the safety of e-cigarettes, evaluating roughly the same studies, have reached significantly different conclusions.[6] Due to various methodological issues, severe conflicts of interest, and inconsistent research, no definite conclusions can be determined regarding the safety of e-cigarettes.[12] However, e-cigarettes cannot be regarded as harmless.[12] There is little data about their safety, and considerable variability among vaporizers and in their liquid ingredients[4] and thus the contents of the aerosol delivered to the user.[5] The health community, pharmaceutical industry, and other groups have raised concerns about the emerging phenomenon of e-cigarettes, including the unknown health risks from long-term use of e-cigarettes.[36] Concern exists that the majority of smokers attempting to quit by vaping may stop smoking but maintain nicotine intake because their long-term effects are not clear.[38] A policy statement by the American Association for Cancer Research and the American Society of Clinical Oncology has reported that "The benefits and harms must be evaluated with respect to the population as a whole, taking into account the effect on youth, adults, nonsmokers, and smokers."[17] A July 2014 World Health Organization (WHO) report cautioned about the potential risks to children and adolescents, pregnant women, and women of reproductive age regarding e-cigarette use.[7]
It is recommended the precautionary principle be used for e-cigarettes because of the long history of the tobacco crisis, in order to assess their benefits and long-term effects and to avoid another nicotine crisis.[39] A 2014 review recommended that e-cigarettes could be adequately regulated for consumer safety with existing regulations on the design of electronic products.[36] Regulation of the production and promotion of e-cigarettes may help lower some adverse effects associated with tobacco use.[34] The entrance of large US tobacco manufacturers, which are Altria Group, Reynolds American, and Lorillard, into the e-cigarette sector raises many potential public health issues.[40] Instead of encouraging quitting, the tobacco industry could market e-cigarettes as a way to get around clean indoor air laws, which promotes dual use.[40] The industry could also lead vapers to tobacco products, which would increase instead of decrease overall addiction.[40]
The health effects related to e-cigarette use is mostly unknown.[41] The health effects on intensive e-cigarette users are unknown.[14] The effect on population health from e-cigarettes is unknown.[8] Smokefree.gov, a website run by the Tobacco Control Research Branch of the National Cancer Institute to provide information to help quit smoking, stated that "Since e-cigs aren't regulated yet, there's no way of knowing how much nicotine is in them or what other chemicals they contain. These two things make the safety of e-cigs unclear."[42] The English National Health Service has stated, "While e-cigarettes may be safer than conventional cigarettes, we don't yet know the long-term effects of vaping on the body."[43] The American Diabetes Association states "There is no evidence that e-cigarettes are a healthier alternative to smoking."[44] In August 2014, the Forum of International Respiratory Societies stated that e-cigarettes have not been demonstrated to be safe.[45]Health Canada has stated that, "their safety, quality, and efficacy remain unknown."[46] The National Institute on Drug Abuse stated that "There are currently no accepted measures to confirm their purity or safety, and the long-term health consequence of e-cigarette use remain unknown."[47]Effects of vaping, compared to tobacco smoking.[48]
A 2015 Public Health England (PHE) report stated that e-cigarettes are estimated to be 95% less harmful than smoking,[49] although this estimate has been disputed.[50] 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."[51] A 2014 systematic review suggests that e-cigarettes are less harmful than smoking because there is no tobacco, no combustion, and users may avoid several harmful constituents usually found in tobacco smoke.[9] 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.[52] Scientific studies advocate caution before designating e-cigarettes as beneficial but vapers continue to believe they are beneficial.[53]
The American Cancer Society has 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."[54] 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."[55] 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.[56] The US National Association of County and City Health Officials has stated, "Public health experts have expressed concern that e-cigarettes may increase nicotine addiction and tobacco use in young people."[57] No long-term studies have evaluated future tobacco use as a result of e-cigarette use.[58] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[31]Possible adverse effects of vaping.[59]
As of 2015, the short-term and long-term effects from using e-cigarettes remain unclear.[14]Adverse effects are mostly associated with short-term use and the reported adverse effects decreased over time.[60] Long-term studies regarding the effects of constant use of e-cigarettes are unavailable.[60] The adverse effects of e-cigarettes on people with cancer is unknown.[17] A 2014 Cochrane review found no serious adverse effects reported in trials,[61] but serious events have been reported in case studies.[13]
The evidence suggests they produce less harmful effects than combusted tobacco.[11] The most frequently reported less harmful effects of vaping compared to smoking were reduced shortness of breath, reduced cough, reduced spitting, and reduced sore throat.[53] Many health benefits are associated with switching from tobacco to e-cigarettes including decreased weight gain after smoking cessation and improved exercise tolerance.[62] 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.[63] Many people use e-cigarettes to quit smoking, but few succeed.[64] They frequently use both, which increases their health risks by using both products.[64] Quitting smoking entirely would probably have much greater beneficial effects to overall health than vaping to decrease the number of cigarettes smoked.[5]
More serious adverse effects frequently related with smoking cessation including depression, insomnia, and anxiety are uncommon with e-cigarette use.[16] A 2015 study found serious adverse events related to e-cigarettes were hypotension, seizure, chest pain, rapid heartbeat, disorientation, and congestive heart failure but it was unclear to the degree they were the result of e-cigarettes.[16] Less serious adverse effects include abdominal pain, headache, blurry vision,[16] throat and mouth irritation, vomiting, nausea, and coughing.[5] Short-term adverse effects reported most often were mouth and throat irritation, dry cough, and nausea.[60] The majority of adverse effects reported were nausea, vomiting, dizziness and oral irritation.[9] Some case reports found harms to health brought about by e-cigarettes in many countries, such as the US and in Europe; the most common effect was dryness of the mouth and throat.[22] 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.[17]
The US Food and Drug Administration Center for Tobacco Products reported between 2008 and the beginning of 2012, 47 cases of adverse effects associated with e-cigarettes, of which eight were considered serious.[13] Two peer-reviewed reports of lipoid pneumonia were related to e-cigarette use, as well as two reports in the media in Spain and the UK.[41] The man from the UK reportedly died from severe lipoid pneumonia in 2011.[41] Reports to the Food and Drug Administration (FDA) for minor adverse effects identified with using e-cigarettes include headache, chest pain, nausea, and cough.[1] Major adverse effects reported to the FDA included hospitalizations for pneumonia, congestive heart failure, seizure, rapid heart rate, and burns.[1] However no direct relationship has been proven between these effects and e-cigarette use, and some of them may be due to existing health problems.[1] Many of the observed negative effects from e-cigarette use concerning the nervous system and the sensory system are probably related to nicotine overdose or withdrawal.[65] 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 adverse effects.[66] E-cigarettes were associated with fewer adverse effects than nicotine patches.[67]Symptoms of nicotine poisoning related to e-cigarette calls to US poison control centers.[68]
Nicotine poisoning related to e-cigarettes include ingestion, inhalation, or absorption via the skin or eyes.[17] Accidental poisoning can result from using undiluted concentrated nicotine when mistakenly used as prepared e-liquids.[69] E-cigarettes involve accidental nicotine exposure in children.[18] Accidental exposures in pediatric patients include ingesting of e-liquids and inhaling of e-cigarette vapors.[18] Choking on e-cigarette components is a potential risk.[18] It is recommended that youth access to e-cigarettes be prohibited.[70]
Four adults died in the US and Europe, after intentionally ingesting liquid.[41] Two children, one in the US in 2014 and another in Israel in 2013, died after ingesting liquid nicotine.[71] Death from accidental nicotine poisoning is very uncommon.[72]
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.[73] Minor, moderate, and serious adverse effects involved adults and young children.[74] Minor effects correlated with e-cigarette liquid poisoning were tachycardia, tremor, chest pain and hypertension.[75] More serious effects were bradycardia, hypotension, nausea, respiratory paralysis, atrial fibrillation and dyspnea.[75] The exact correlation is not fully known between these effects and e-cigarettes.[75] 58% of e-cigarette calls to US poison control centers were related to children 5 years old or less.[74] 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.[74] Most of the e-cigarette and traditional cigarette calls were a minor effect.[74] Severe outcomes were more than 2.5 times more frequent in children exposed to e-cigarettes and nicotine e-liquid than with traditional cigarettes.[76] E-cigarette sales were roughly equivalent to just 3.5% of traditional cigarette sales, but of the total number of e-cigarette and traditional cigarette calls to US poison control centers in December 2014, the reported e-cigarettes calls were 44%.[74]Poison control center calls in the US related to e-cigarettes was one call per month in September 2010 to over 200 calls per month in February 2014.[77]
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;[74] inhalation/nasal exposure resulted in nausea, vomiting, dizziness, agitated, or headache;[74] ocular exposure resulted in eye irritation or pain, red eye or conjunctivitis, blurred vision, headache, or corneal abrasion;[74] multiple routes of exposure resulted in eye irritation or pain, vomiting, red eye or conjunctivitis, nausea, or cough;[74] and dermal exposure that resulted in nausea, dizziness, vomiting, headache, or tachycardia.[74] 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%).[74] In nine reported calls, exposed individuals stated the device leaked.[74] In five reported calls, individuals used e-liquid for their eyes rather than use eye drops.[74] In one reported call, an infant was given the e-liquid by an adult who thought it was the infant's medication.[74] There were also reports of choking on e-cigarette components.[18]
From January 1, 2016 and April 30, 2016, the American Association of Poison Control Centers (AAPCC) reported 623 exposures related to e-cigarettes.[64] The AAPCC reported 3,067 exposures relating to e-cigarettes and liquid nicotine in 2015, and 3,783 in 2014.[78] From September 1, 2010 to December 31, 2014, there were at least 5,970 e-cigarette calls to US poison control centers.[74] Calls to US poison control centers related to e-cigarettes increased between September 2010 to February 2014, and of the total number of cigarettes and e-cigarettes calls, e-cigarette calls increased from 0.3% to 41.7%.[67] Calls to US poison controls centers related to e-cigarette liquid poisoning increased from 1 in September 2010 to 215 for the month of February 2014.[75] E-cigarette calls was 401 for the month of April 2014.[74] The California Poison Control System reported 35 cases of e-cigarette contact from 2010 to 2012, 14 were in children and 25 were from accidental contact.[9]Fruit flavored e-liquids.
There is a possibility that inhalation, ingestion, or skin contact can expose people to high levels of nicotine.[34] Concerns with exposure to the e-liquids include leaks or spills and contact with contaminants in the e-liquid.[79] This may be especially risky to children, pregnant women, and nursing mothers.[34] The liquid quickly absorbs into the skin.[80] The nicotine in e-liquid can be hazardous to infants.[81] Even a portion of e-liquid may be lethal to a little child.[82] An excessive amount of nicotine for a child that is capable of being fatal is 0.1–0.2 mg/kg of body weight.[34] Less than a 1 tablespoon of contact or ingestion of e-liquid can cause nausea, vomiting, cardiac arrest, seizures, or coma.[83] An accidental ingestion of only 6 mg may be lethal to children.[38][84]
Children are susceptible to ingestion due to their curiosity and desire for oral exploration.[76] E-cigarettes are packed in colorful containers[74] and children may be attracted to the flavored liquids.[58] More youth-oriented flavors include "My Birthday Cake" or "Tutti Frutti Gumballs".[71] Many nicotine cartridges and bottles of liquid are not child-resistant to stop contact or accidental ingestion of nicotine by children.[11] "Open" e-cigarette devices, with a refillable tank for e-liquids, are believed to be the biggest risk to young children.[83] It is recommended that e-cigarettes be kept in a safe place, where children and pets do not have access to them.[85]
Nicotine toxicity is of concern when e-cigarette solutions are swallowed intentionally by adults as a suicidal overdose.[40] Six people attempted suicide by injecting e-liquid.[41] One adolescent attempted suicide by swallowing the e-liquid.[18] Three deaths were reported to have resulted from swallowing or injecting e-liquid containing nicotine.[41] An excessive amount of nicotine for an adult that is capable of being fatal is 0.5–1 mg/kg of body weight.[34] An oral lethal dose for adults is about 30–60 mg.[53] 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.[86] Reports of serious adverse effects associated with acute nicotine toxicity that resulting in hospitalization were very uncommon.[87] Death from intentional nicotine poisoning is very uncommon.[72] Clear labeling of devices and e-liquid could reduce unintentional exposures.[74] Child-proof packaging and directions for safe handling of e-liquids could minimize some of the risks.[81] In January 2016, the Child Nicotine Poisoning Prevention Act of 2015 was passed into law in the US,[88] which requires child-proof packaging.[89]
There was inconsistent labeling of the actual nicotine content on e-liquid cartridges from some brands,[5] and some nicotine has been found in 'no nicotine' liquids.[21] A 2015 PHE report noted overall the labelling accuracy has improved.[90] Most inaccurately-labelled examples contained less nicotine than stated.[90] Due to nicotine content inconstancy, it is recommended that e-cigarette companies develop quality standards with respect to nicotine content.[24]
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.[81] 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.[38] This includes leaking cartridges, accidental contact with nicotine when changing cartridges, and potential of unintended overdose.[38] 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."[91]
Cannabinoid-containing e-liquids need lengthy, complex processing, some being available online without any toxicological and clinical evaluation.[92] It is thought that cannabinoids vaped at reduced temperatures is safer because it creates smaller amounts of toxicants than the burning of a hot cannabis cigarette.[92] The health effects of vaping cannabis formulations is mostly unknown.[92]
Most e-cigarettes use lithium batteries, the improper use of which may result in accidents.[9] It has been recommended that manufacturing quality standards be imposed in order to prevent such accidents.[9] Better product design and standards could probably reduce some of the risks.[79] Concern exists from risks associated with e-cigarette explosions for children and adults.[18]
Some batteries are not well designed, are made with poor quality components, or have defects.[1] Major injuries have occurred from battery explosions and fires.[5] 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.[93] A young man endured bilateral corneal burns to the eye area when an e-cigarette exploded near his chest.[93] E-cigarette explosions have resulted in burns, lost teeth, neck fractures, and battery acid contact to the face, mouth, and eyes.[93] A man died when charging an e-cigarette blown up and caught on fire next to oxygen equipment.[93] House and car fires and skin burns have resulted from some of the explosions.[1] The explosions were the result of extended charging, use of unsuitable chargers, or design flaws.[9] There is a possible risk to bystanders from e-cigarette explosions.[93] There is also a risk of property damage as a result of flammable materials catching on fire from an e-cigarette explosion.[93] The United States Fire Administration said that 25 fires and explosions were caused by e-cigarettes between 2009 and August 2014.[94] In the UK fire service call-outs had risen, from 43 in 2013 to 62 in 2014.[95] A 2015 PHE report concluded that the risks of fire from e-cigarettes "appear to be comparable to similar electrical goods".[96] Since e-cigarettes are not subjected to product safety testing, they may not have safety designs to avoid overheating, thermal runaway, and battery failure including fire and explosions.[93] There is inadequate product labeling to inform users of the possible serious harms.[93] The risk from serious adverse effects is low, but the aftermath may be disastrous in respect to an e-cigarette blast.[93] Victims have filed lawsuits to make restitution from the e-cigarette blasts.[41] Adverse effects may be under-reported because reports to the FDA is voluntary.[93]
In January 2015 the US Federal Aviation Administration issued a safety alert to air carriers that e-cigarettes should not be allowed in checked baggage after a review of fire safety issues, including two fires caused by e-cigarettes in checked baggage.[94][97] The International Civil Aviation Organization, a United Nations agency, also recommends prohibiting e-cigarettes in checked luggage.[94] A spokesman for the Tobacco Vapor Electronic Cigarette Association said that e-cigarettes do not pose a problem if they are packed correctly in static-free packaging, but that irresponsible people may sometimes pack them carelessly or tamper with them.[94] In-flight use of e-cigarettes is prohibited in the US.[97]
Users may alter many of the devices, such as using them to administer other drugs like cannabis.[5] E-liquid mixing is another way users tamper with e-cigarettes.[98] Mixing liquid in an unclean area runs the risk of contamination.[16] Users may add various flavorings and diluents.[98] Vodka or other forms of alcohol may also be added.[98] The addition of alcohol or nicotine could expose the user to more toxicants, especially when added in combinations.[98] 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.[98] Users can adjust the voltage of some e-cigarettes.[98] 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.[19] Some users add more or larger batteries to nonadjustable e-cigarettes, which may lead to battery leakage or explosion.[98] 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.[18]
The long-term health impacts of e-cigarette use are unknown.[13] The long-term health impacts of the main chemicals nicotine and propylene glycol in the aerosol are not fully understood.[99] There is limited peer-reviewed data about the toxicity of e-cigarettes for a complete toxicological evaluation,[100] and their cytotoxicity is unknown.[15] The chemicals and toxicants included in e-cigarettes have not been completely disclosed and their safety is not guaranteed.[34] They are similar in toxicity to other nicotine replacement products,[101] but e-cigarettes manufacturing standards are variable standards, and many as a result are probably more toxic than nicotine replacement products.[102] The UK National Health Service noted that the toxic chemicals found by the FDA were at levels one-thousandth that of cigarette smoke, and that while there is no certainty that these small traces are harmless, initial test results are reassuring.[103] While there is variability in the ingredients and concentrations of ingredients in e-cigarette liquids, tobacco smoke contains thousands of chemicals, most of which are not understood and many of which are known to be harmful.[36]
Concerns about the carcinogenicity of e-cigarettes arise from both nicotine[28] and from other chemicals that may be in the vapor.[24] 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.[28] 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".[29] 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".[29] Nicotine in the form of nicotine replacement products is less of a risk than compared to smoking,[29] and they have not been shown to be associated with cancer in the real world.[28]
There is no long-term research concerning the cancer risk related to the potentially small level of exposure to the identified carcinogens in the vapor.[8] In May 2014, Cancer Research UK stated that there are "very preliminary unpublished results that suggest that e-cigarettes promote tumour growth in human cells."[99] The e-cigarette vapors triggered DNA strand breaks and lowered cell survival in vitro.[41] A 2013 study found some samples of e-cigarette vapors had cytotoxic effects on cardiac muscle cells, though the effects were less than with cigarette smoke.[10] In October 2012, the World Medical Association stated, "Manufacturers and marketers of e-cigarettes often claim that use of their products is a safe alternative to smoking, particularly since they do not produce carcinogenic smoke. However, no studies have been conducted to determine that the vapor is not carcinogenic, and there are other potential risks associated with these devices."[104]Chart showing various toxicants as measured in cigarette smoke and e-cigarette aerosol.[105]
Since nicotine-containing e-liquids are made from tobacco they may contain impurities like cotinine, anabasine, anatabine, myosmine and beta-nicotyrine.[13] The majority of e-cigarettes evaluated included carcinogenic tobacco-specific nitrosamines (TSNAs); heavy metals such as cadmium, nickel, and lead; and the carcinogen toluene.[34] However, in comparison to traditional cigarette smoke, the toxic substance levels identified in e-cigarette vapor were 9- to 450-fold less.[34] E-liquid with tin was cytotoxic.[12] E-cigarettes cannot be considered absolutely safe because there is no safe level for carcinogens.[106]
A 2014 review found higher levels of carcinogens and toxicants than in an FDA-approved nicotine inhaler, suggesting that FDA-approved devices may deliver nicotine more safely.[8] In 2014, The World Lung Foundation 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."[107]
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."[24] Few of the methods used to analyze the chemistry of e-cigarettes in the studies the review evaluated were validated.[24]The propylene glycol molecule.
The primary base ingredients of the liquid solution is propylene glycol and glycerin.[5] About 20% to 27% of propylene glycol and glycerin-based liquid particles are inhaled.[108] The long-term effects of inhaled propylene glycol has not been studied,[58] and is unknown.[109] The effects of inhaled glycerin are unknown.[84] Being exposed to propylene glycol may cause irritation to the eyes and respiratory tract.[5] The risk from the inhalation of propylene glycol and glycerin is probably low.[13] Propylene glycol and glycerin have not been shown to be safe.[84] Some research states that propylene glycol emissions may cause respiratory irritation and raise the likelihood to develop asthma.[52] Long-term inhalation of propylene glycol indoors could increase risk to children to develop asthma.[38] To lessen the risks, most e-cigarettes companies began to use water and glycerin as replacement for propylene glycol.[52] The inhaled glycerin could cause lipoid pneumonia.[16]
Some e-cigarette products had acrolein identified in the aerosol.[13] It may be generated when glycerin is heated to higher temperatures.[13] Acrolein may induce irritation to the upper respiratory tract.[5] Acrolein levels were reduced by 60% in dual users and 80% for those that completely switched to e-cigarettes when compared to traditional cigarettes.[13] E-cigarettes vapor have been found to create oxidants and reactive oxygen species (OX/ROS).[19] OX/ROS could react with other substances in the vapor because they are highly reactive.[19] Although e-cigarettes have been found to contain OX/ROS at about 100 times less than in cigarette smoke, they probably induce meaningful biological effects.[19]
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.[100] 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.[33] The short-term toxicity of e-cigarette use appears to be low, with the exception for some people with reactive airways.[21]The ingredients in an e-cigarette cartridge: Distilled water, Nicotine, FCC Grade Vegetable Glycerin, Natural Flavors, Artificial Flavors, Citric Acid. Nicotine content 6-8 mg per cartridge.
The essential propylene glycol and/or glycerin mixture may consist of natural or artificial substances to provide it flavor.[21] The cytotoxicity of e-liquids varies,[20] and contamination with various chemicals have been detected in the liquid.[21] Some liquids were very toxic and others had little or no cytotoxicity.[20] The cytotoxicity is mostly due to the amount and number of flavors added.[20] Since nicotine has a bitter taste, nicotine e-liquids contain chemicals to cover up the nicotine taste.[19] The liquids contain aromatic substances like tobacco, fruit, vanilla, caramel and coffee.[21] Generally, these additives are imprecisely described, using terms such as "vegetable flavoring".[21] Although they are approved for human consumption there are no studies on the short-term or long-term effects of inhaling them.[21] The safety of inhaling flavors is mostly unknown,[110] and their safety has not been determined by the Flavor and Extract Manufacturers Association.[41] In some cases e-liquids contain very large amounts of flavorings, which may cause irritation and inflammation on respiratory and cardiovascular systems.[69] Some flavors are regarded as toxic and a number of them resemble known carcinogens.[21] Some artificial flavors are known to be cytotoxic.[21] Unflavored vapor is less cytotoxic than flavored vapor.[23] A 2012 study demonstrated that in embryonic and adult cellular models, some substances of the vapor such as flavoring not found in tobacco smoke were cytotoxic.[111]
Cinnamaldehyde has been described as a highly cytotoxic material in vitro in cinnamon-flavored refill liquids.[1] Cinnamaldehyde have been identified as cytotoxic at the amount of about 400 times less than those allowed for use by the US Environmental Protection Agency.[9] Some e-liquids containing cinnamaldehyde stimulate TRPA1, which might induce effects on the lung.[19] E-liquids contain possibly toxic aldehydes and reactive oxygen species (ROS).[19] Many flavors are known aldehydes, such as anisaldehyde, cinnamaldehyde, and isovaleraldehyde.[19] The effects of aldehyde-containing flavors on pulmonary surfaces are unknown.[19] A 2012 study found butterscotch flavor was highly toxic with one liquid and two others had a low toxicity.[40] A 2014 in vitro study demonstrated that e-cigarette use of a "balsamic" flavor with no nicotine can activate the release of proinflammatory cytokine in lung epithelial cells and keratinocytes.[34] Some additives may be added to reduce the irritation on the pharynx.[84] The long-term toxicity is subject to the additives and contaminants in the e-liquid.[21]
Certain flavorings contain diacetyl and acetyl propionyl which give a buttery taste.[31] Diacetyl and acetyl propionyl are associated with bronchiolitis obliterans.[31] A 2015 review recommended for specific regulation of diacetyl and acetyl propionyl in e-liquid, which are safe when ingested but have been associated with respiratory harm when inhaled.[6] Both diacetyl and acetyl-propionyl have been found in concentrations above those recommended by the US National Institute for Occupational Safety and Health.[31] Diacetyl is normally found at lower levels in e-cigarettes than in traditional cigarettes.[31] Concerns exist that the flavors and additives in e-cigarettes might lead to diseases, including the popcorn lung.[112] The cardiovascular effects, including a vast range of flavorings and fragrances, is unknown.[113] The irritants butyl acetate, diethyl carbonate, benzoic acid, quinoline, bis(2-ethylhexyl) phthalate, and 2,6-dimethyl phenol were present as undeclared ingredients in the e-liquid.[62] The precise ingredients of e-cigarettes are not known.[114]
The IARC has categorized formaldehyde as a human carcinogen, and acetaldehyde is categorized as a potential carcinogenic to humans.[22] Aldehydes may cause harmful health effects; though, in the majority of cases, the amounts inhaled are less than with traditional cigarettes.[22] Many chemical compounds can inadvertently be produced from e-cigarettes, especially carbonyl compounds like formaldehyde, acetaldehyde, acrolein, and glyoxal by the chemical reaction of the e-liquid when the nichrome wire (heating element) is heated,[22] to high temperatures.[34] These compounds are frequently identified in e-cigarette aerosols.[22] The propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette aerosols.[22] The levels of toxic chemicals in the vapor were found to be 1 to 2 orders of magnitude smaller than with cigarette smoke but greater than from a nicotine inhaler.[5] Nearly all e-cigarettes evaluated, toxic and irritation-causing carbonyls were identified.[34] Reports regarding the levels of toxic chemicals were inconsistent.[34] This includes a study showing that the levels of toxicants in e-cigarettes may be higher than with cigarette smoke.[34]
Battery output voltage influences the level of the carbonyl substances in the vapor.[22] A few new e-cigarettes let users boost the amount of vapor and nicotine provided by modifying the battery output voltage.[22] E-cigarettes with higher voltages (5.0 V[20]) can emit carcinogens including formaldehyde at levels comparable to cigarette smoke,[115] while reduced voltages (3.0 V[24]) generate aerosol with levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than in cigarette smoke.[22] "Dripping", where the liquid is dripped directly onto the atomizer, can create carbonyls including formaldehyde.[116]
A 2015 PHE report found that normal e-cigarette use generates very low levels of aldehydes.[26] Normal usage of e-cigarettes generates very low levels of formaldehyde,[23] and at normal settings they generate very low levels of formaldehyde.[26] Later-generation e-cigarettes used with higher power may generate equal or higher levels of formaldehyde than compared to smoking.[14][Notes 2] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[25] 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.[26] Users detect the "dry puff" and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[27] However, e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[19]Possible side effects of nicotine.[117] A 2015 comparative risk analysis of drugs found the nicotine's margin of exposure (MOE) values were in a lower risk range than cocaine, heroine, and alcohol, whereas its MOE values was in a higher risk range than MDMA, methamphetamine, and methadone.[118] Shown above is the MOE for daily drug use from the analysis.[118]
Pregnant women, breastfeeding mothers, and the elderly are more sensitive to nicotine than other individuals.[110] There are safety issues with the nicotine exposure from e-cigarettes, which may cause addiction and other adverse effects.[24] Nicotine is regarded as a potentially lethal poison.[17] Concerns exist that vaping can be harmful by exposing users to toxic levels of nicotine.[17] At low amounts, it has a mild analgesic effect.[110] At high enough doses, nicotine may result in nausea, vomiting, diarrhea, salivation, bradyarrhythmia, and possibly seizures and hypoventilation.[35] However, at the low amount of nicotine provided by e-cigarettes fatal overdose from use is unlikely; in contrast, the potent amount of nicotine in e-cigarettes liquids may be toxic if it is accidentally ingested or absorbed via the skin.[17] The health effects of nicotine in infants and children are unclear.[35]
E-cigarettes provide nicotine to the blood quicker than nicotine inhalers.[53] The levels were above that of nicotine replacement product users.[17] E-cigarettes seem to have a pharmacokinetic nicotine profile closer to nicotine replacement products than with traditional cigarettes.[119] How efficiently different e-cigarettes give nicotine is unclear.[17]Serum cotinine levels are comparable to that of traditional cigarettes,[120] but are inharmonious and rely upon the user and the device.[8] Blood nicotine levels raised more gradually and took more time to get to peak concentration with e-cigarettes than with traditional cigarettes.[121]
When compared to traditional cigarettes older devices usually delivered low amounts of nicotine.[17] 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.[122] This is due to the minute nicotine particles in the vapor, which permit quick delivery into the bloodstream.[122] The nicotine delivered from e-cigarettes enters the body slower than traditional cigarettes.[123] Studies suggest that inexperienced users obtain moderate amounts of nicotine from e-cigarettes.[124] Concerns were raised over inconsistent amounts of nicotine delivered when drawing on the device.[125]
Later-generation e-cigarettes gives nicotine more effectively than first-generation e-cigarettes.[1] Later-generation models with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[17] E-cigarettes with stronger batteries heat solutions to higher temperatures, which may raise blood nicotine levels to those of traditional cigarettes.[40] Research suggests that experienced e-cigarettes users are able to get as much nicotine from e-cigarettes as traditional cigarettes.[17] Later-generation e-cigarettes containing sufficient nicotine elevates heart rate comparable to traditional cigarettes.[113]
The health effects of long-term nicotine use is unknown.[109] It may be decades before the long-term health effects of nicotine vapor inhalation is known.[126] It is not recommended for non-smokers.[9] Nicotine affects practically every cell in the body.[110] Nicotine can cause high blood pressure and abnormal heart rhythms.[107] Vapers that get a higher amount of blood nicotine are probably correlated with increased heart rates.[87] Nicotine may have adverse effects on lipids,[127] cause insulin resistance.[40] and can lower coronary blood flow.[113] Nicotine lowers estrogen levels and has been associated with early menopause in women.[107] Nicotine could have cancer-promoting properties, therefore long-term use may not be harmless.[98] Nicotine may result in neuroplasticity variations in the brain.[80] Nicotine could make cancer therapies less effective.[16]
Children are more sensitive to nicotine than adults.[110] In youth, nicotine may affect capabilities connected with higher cognitive function processes,[35] later achievement, as well as the chance of nicotine addiction for life.[107] The adolescents developing brain is especially sensitive to the harmful effects of nicotine.[82] A short period of regular or occasional nicotine exposure in adolescence exerts long-term neurobehavioral damage.[82] In August 2014, the American Heart Association noted that "e-cigarettes could fuel and promote nicotine addiction, especially in children."[40] A policy statement by the UK's Faculty of Public Health has stated, "A key concern for everyone in public health is that children and young people are being targeted by mass advertising of e-cigarettes. There is a danger that e-cigarettes will lead to young people and non-smokers becoming addicted to nicotine and smoking. Evidence from the US backs up this concern."[128]
There is limited evidence on the long-term exposure of metals.[9] Exposure to the levels and kinds of metals found in the aerosol relies upon the material and other manufacturing designs of the heating element.[40] 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.[9] The device itself could contribute to the toxicity from the tiny amounts of silicate and heavy metals found in the liquid and vapor,[116] because they have metal parts that come in contact with the e-liquid.[9] Low levels of possibly harmful chromium, lead, and nickel metals have been found in the emissions.[40] Chromium and nickel nanoparticles have also been found.[5]
Metals may adversely affect the nervous system.[70] A 2013 review found metallic and nanoparticles are associated with respiratory distress and disease.[129] 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.[34] A 2013 study found metal particles in the aerosol were at levels 10-50 times less than permitted in inhalation medicines.[13] A 2014 review suggested that there is no evidence of contamination of the aerosol with metals that justifies a health concern.[33]
Abbreviations: μg, microgram; ng, nanogram; ND, not detected.[20]
∗Fifteen puffs were chosen to estimate the nicotine delivery of one traditional cigarette.[20]
The risks to the lungs are not fully understood,[19] and concern exists regarding the negative effects on lung function.[130] There is limited evidence on the long-term health effects to the lungs.[14] Many ingredients used in e-liquids have not been examined in the lung.[19] The effects of e-cigarette use in respect to asthma and other respiratory diseases are unknown.[13] A 2015 review found e-cigarettes may induce acute lung disease.[14] A 2015 study found that e-cigarette vapors can induce oxidative stress in lung endothelial cells.[69] Constant lung inflammation as a result of the vapor could result in lung pathogenesis and induce serious diseases, including chronic obstructive pulmonary disease and fibrosis.[41] The limited evidence suggests that e-cigarettes produce less short-term effects on lung function than traditional cigarettes.[8] A 2014 case report observed the correlation between sub-acute bronchiolitis and vaping.[14] After quitting vaping the symptoms improved.[14]
The long-term effects regarding respiratory flow resistance are unknown.[60] E-cigarettes could harm the respiratory system.[21] The immediate effects of e-cigarettes after 5 minutes of use on pulmonary function resulted in considerable increases in resistance to lung airflow.[1] A 2013 review found an instant increase in airway resistance after using a single e-cigarette.[21] Any reported harmful effects to cardiovascular and respiratory functions after short-term use of e-cigarettes were appreciably milder in comparison to cigarette smoke.[9] When used in the short-term, an e-cigarette resulted in a rise of respiratory resistance comparatively to traditional cigarettes.[60] E-cigarette use could result in respiratory diseases among youth.[131]
There is no data available on the long-term cardiovascular effects.[8] There is no published research available on vaping and thrombosis, platelet reactivity, atherosclerosis, or blood vessel function.[14] The minute nicotine particles in the vapor could increase the risk of cardiac arrhythmias and hypertension which may put some users, particularly those with atherosclerosis or other cardiovascular risk factors, at significant risk of acute coronary syndrome.[122] Some case reports documented the possible cardiovascular adverse effects from using e-cigarettes, the majority associated was with improper use.[122] Even though e-cigarettes are anticipated to produce fewer harmful substances than traditional cigarettes, limited evidence supports they comparatively have a lessened raised cardiovascular risk.[122] E-cigarette use leads to sympathomimetic effects because of nicotine intake.[132] It is argued that there could be a risk for harmful effects, including tachycardia-induced cardiomyopathy.[132] E-cigarettes containing nicotine may have a lower cardiovascular effect than traditional cigarettes containing nicotine.[113] Short-term physiological effects include increases in blood pressure and heart rate.[14] A 2012 case report found a correlation between paroxysmal atrial fibrillation and vaping.[14]
Comparable to a traditional cigarette, e-cigarette particles are tiny enough to enter the alveoli, enabling nicotine absorption.[1] These particles are also tiny enough to go deep in the lungs and enter into the systemic circulation.[5] Local pulmonary toxicity may occur because metal nanoparticles can deposit in the lung's alveolar sacs.[5] E-cigarettes companies assert that the particulates produced by an e-cigarette are too tiny to be deposited in the alveoli.[53] Different devices generate different particle sizes and cause different depositions in the respiratory tract, even from the same nicotine liquid.[115] The aerosol production of e-cigarettes during vaping decreases, which requires a more forceful suction to create a similar volume of aerosol.[66] A more forceful suction could affect the deposition of substances into the lungs.[66] Reports in the literature have shown respiratory and cardiovascular effects by these smaller size particles, suggesting a possible health concern.[133]
Concern exists regarding the immunological effects of e-liquid, and analysis on animals demonstrate that e-liquid vapor, appear to have adverse effects on the immune system.[87] There were reports of e-cigarettes causing an immune system reaction involving inflammation of the gastrointestinal system.[41] Long-term use could increase the risk of tuberculosis.[12] It is possible that e-cigarettes could harm the periodontium because of the effects of nicotine on gum tissues and the immune system.[134] Some health effects associated with e-cigarette use can include recurring ulcerative colitis, lipoid pneumonia, acute eosinophilic pneumonitis, sub-acute bronchial toxicity, reversible cerebral vasoconstriction syndrome, and reversal of chronic idiopathic neutrophilia.[87]Aerosol (vapor) exhaled by an e-cigarette user.
The aerosol of e-cigarettes is generated when the e-liquid reaches a temperature of roughly 100-250 °C within a chamber.[19] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[24] 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.[24] The aerosol is made-up of liquid sub-micron particles of condensed vapor,[135] which mostly consist of propylene glycol, glycerol, water, flavorings, nicotine, and other chemicals.[9] After a puff, inhalation of the aerosol travels from the device into the mouth and lungs.[24] The particle size distribution and sum of particles emitted by e-cigarettes are like traditional cigarettes, with the majority of particles in the ultrafine range.[5]Various bottles of e-liquid.
After the aerosol is inhaled, it is exhaled.[24] Emissions from electronic cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different[9] The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled vapor.[21] Bystanders are exposed to these particles from exhaled e-cigarette vapor.[5] There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors, and have significant adverse effects.[34][129] Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted.[123] Thus, cardiocirculatory effects caused by carbon monoxide are not likely.[123] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[35] E-cigarettes pose many safety concerns to children.[35] 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.[35]
E-liquid is the mixture used in vapor products such as electronic cigarettes.[52] The main ingredients in the e-liquid usually are propylene glycol, glycerin, nicotine, and flavorings.[101] However, there are e-liquids sold without propylene glycol, nicotine, or flavors.[17][52][61] The liquid typically contains 95% propylene glycol and glycerin.[84] The flavorings may be natural or artificial.[21] About 8,000 flavors exist as of 2014.[136] There are many e-liquids manufacturers in the USA and worldwide.[137] While there are currently no US Food and Drug Administration (FDA) manufacturing standards for e-liquid, the FDA has proposed regulations that are expected to be finalized in late 2015.[138] Industry standards have been created and published by the American E-liquid Manufacturing Standards Association (AEMSA).[139]
Concerns exists regarding pregnant women exposure to e-cigarette vapor through direct use or via exhaled vapor.[5] No evidence have shown that e-cigarettes are safe to use for pregnant women.[140] No amount of nicotine is safe for pregnant women.[140] As of 2014[update], there are no conclusions on the possible hazards of pregnant women using e-cigarettes, and there is a developing research on the negative effects of nicotine on prenatal brain development.[8] E-cigarette are assumed to be dangerous to the fetus during pregnancy if e-cigarettes are used by the mother.[141] Nicotine is harmful to the growing fetus.[142] Nicotine accumulates in the fetus because it goes through the placenta.[38]
As of 2015[update], the long-term issues of e-cigarettes on both mother and unborn baby are unknown.[143] Prenatal nicotine exposure is associated with adverse effects on the growing fetus, including effects to normal growth of the endocrine, reproductive, respiratory, cardiovascular, and neurologic systems.[140] Prenatal nicotine exposure is associated with lower birth weights than other babies,[140]stillbirth,[82]sudden infant death syndrome, and alterations to normal brain development.[140] Prenatal nicotine exposure is associated with asthma and wheezing which may continue into adulthood.[140]Gestational age nicotine exposure is associated with many neurological deficits.[140] Prenatal exposure has been associated with obesity, diabetes, high cholesterol and high blood pressure in minors.[107] Prenatal nicotine exposure in females may lead toward early menarche.[140] An infant was born with necrotizing enterocolitis due to e-cigarette use during pregnancy.[41]
In what way the e-liquid ingredients could affect a fetus is unknown.[2] The toxicity of e-liquid flavorings was higher in embryonic stem cells compared to differentiated adult pulmonary fibroblasts, leading to concerns about pregnant women being exposed to the second-hand vapor.[109] There are concerns about the health impacts of pediatric exposure to second-hand and third-hand e-cigarette vapor.[18] The Surgeon General's 2014 report found "that nicotine adversely affects maternal and fetal health during pregnancy, and that exposure to nicotine during fetal development has lasting adverse consequences for brain development."[17] The belief that e-cigarettes are safer than traditional cigarettes could increase their use in pregnant women.[1] The toxic effects identified with e-cigarette refill liquids on stem cells may be interpreted as embryonic death or birth defects.[1] Since e-cigarettes are not validated as cessation tools, may contain nicotine at inconsistent levels and added ingredients that are possibly harmful, allowing e-cigarettes to be used among pregnant women to decrease smoking puts this group at considerable risk.[35] There is concern for breastfeeding women using e-cigarettes, due to the lack of data on propylene glycol transferring to breastmilk.[21]
There is limited information available on any environmental issues connected to the production, usage, and disposal of e-cigarette models that use cartridges.[37] As of 2014[update], no formal studies have been done to evaluate the environmental effects of making or disposing of any part of e-cigarettes including the batteries or nicotine production.[37] As of 2014[update], it is uncertain if the nicotine in e-liquid is United States Pharmacopeia-grade nicotine, a tobacco extract, or synthetic nicotine when questioning the environmental impact of how it is made.[37] It is not clear which manufacturing methods are used to make the nicotine used in e-cigarettes.[37] The emissions from making nicotine could be considerable from manufacturing if not appropriately controlled.[37] Some e-cigarette brands that use cartridges state their products are 'eco-friendly' or 'green', despite the absence of any supporting studies.[37] Some writers contend that such marketing may raise sales and increase e-cigarette interest, particularly among minors.[37]
It is unclear how many traditional cigarettes are comparable to using one e-cigarette that uses a cartridge for the average user.[37] Information is limited on energy and materials used for production of e-cigarettes versus traditional cigarettes, for comparable use.[37] E-cigarettes can be made manually put together in small factories, or they can be made in automated lines on a much bigger scale.[37] Larger plants will produce greater emissions to the surrounding environment, and thus will have a greater environmental impact.[37] Although some brands have begun recycling services for their e-cigarette cartridges and batteries, the prevalence of recycling is unknown, as is the prevalence of information provided by manufacturers on how to recycle disposable parts.[37] A 2014 review found "disposable e-cigarettes might cause an electrical waste problem."[123] Since the majority of e-cigarettes are reusable they are possibly more environmentally friendly than using single-use devices.[144] Compared to traditional cigarettes, e-cigarettes do not create litter in the form of discarded cigarette butts.[144] Traditional cigarette tend to end up in the ocean where they cause pollution.[144]
Marketing and advertisement affects the public's perception of e-cigarettes.[109] Some tobacco users think vaping is safer than tobacco or other smoking cessation aids.[145] It is generally considered by users that e-cigarettes are safer than tobacco.[114] Many users think that e-cigarettes are healthier than traditional cigarettes for personal use or for other people.[58] Usually, only a small proportion of users are concerned about the possible adverse health effects or toxicity of e-cigarettes.[58] 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.[146] A 2013 four-country survey found higher than 75% of current and former smokers think e-cigarettes are safer than traditional cigarettes.[1] The UK Action on Smoking and Health (ASH) 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".[147] 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."[147] The UK 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."[147]
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.[148] 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,and concluded that "There is a need to publicise the current best estimate that using EC is around 95% safer than smoking".[duplication?][149]
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