Misplaced Pages

Revision as of 13:45, 21 November 2015

The long term safety of Electronic Cigarettes is unknown. The evidence indicates they are less harmful than traditional cigarettes and the well understood harms of combustible tobacco. In 2015, Public Health England released a report stating that e-cigarettes are estimated to be 95% less harmful than smoking. While later-generation and "hotter" e-cigarettes (e.g. 5.0 volts) may generate equal or higher levels of formaldehyde than smoking, reduced voltage e-cigarettes generate very low levels of formaldehyde. A 2015 Public Health England concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes." One review found, from limited data, their safety risk is similar to that of smokeless tobacco, which has about 1% of the mortality risk of traditional cigarettes.

The e-liquid has a low level of toxicity, and contamination with various chemicals has been identified in the product. A few metal parts in e-cigarettes can contact the e-liquid and contaminate it with metals. Many chemicals including carbonyl compounds such as formaldehyde can inadvertently be produced when the nichrome wire that touches the e-liquid is heated and chemically reacts with the liquid. E-cigarettes create vapor that consists of ultrafine particles, with the majority of particles in the ultrafine range. 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. Exactly what comprises the vapor varies in composition and concentration across and within manufacturers. Due to various methodological issues, severe conflicts of interest, and inconsistent research, no definite conclusions can be determined regarding the safety e-cigarettes. However, e-cigarettes cannot be regarded as simply harmless. Aside from toxicity, there are also risks from misuse or accidents such as accidental contact with liquid nicotine, accidental fires caused by vaporizer malfunction, and explosions resulting from extended charging, use of unsuitable chargers, or vaporizer design flaws. There is a small risk of battery explosion in devices modified to increase battery power. Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.

A July 2014 World Health Organization (WHO) report cautioned about potential risks of using e-cigarettes. The report concluded that "the existing evidence shows that ENDS aerosol is not merely "water vapour" as is often claimed in the marketing for these products. ENDS use poses serious threats to adolescents and fetuses." 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. E-cigarette vapor contains fewer toxic substances than cigarette smoke. It also has lower concentrations of potential toxic substances than cigarette smoke. There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors. E-cigarette use by a parent might lead to inadvertent health risks to offspring.

The long-term effects of e-cigarette use are unknown. A 2014 Cochrane review found no serious adverse effects reported in trials. Less serious adverse effects from e-cigarette use include throat and mouth inflammation, vomiting, nausea, and cough. The risk is probably low from the inhalation of propylene glycol and glycerin. No information is available on the long-term effects of the inhalation of flavors. E-cigarette users are exposed to potentially harmful nicotine. Nicotine is associated with cardiovascular disease, potential birth defects, and poisoning. In vitro studies of nicotine have associated it with cancer, but carcinogenicity has not been demonstrated in vivo. There is inadequate research to demonstrate that nicotine is associated with cancer in humans. A 2014 review recommended that e-cigarettes should be regulated for consumer safety. There is limited information available on the environmental issues around production, use, and disposal of e-cigarettes that use cartridges.

Health effects

Health benefits and concerns

The emerging phenomenon of e-cigarettes is raising concerns among the health community, pharmaceutical industry, and other groups. One concern is the unknown health risks from the use of e-cigarettes over the long-term. A 2014 review recommended that e-cigarettes should be adequately regulated for consumer safety. Another 2014 review stated these products should be considered for regulation in view of the "reported adverse health effects". For example, they found that "The Food and Drug Administration (FDA) reported that e-cigarettes contain carcinogens and toxic chemicals, such as nitrosamines and diethylene glycol, which have potentially harmful effects on humans." Moreover, a WHO report in 2009 cautioned that the "safety of e-cigarettes is not confirmed."

In several countries advertising for e-cigarettes has been monetarily restricted until safety and efficacy clinical trials are conclusive. A 2014 systematic review found that the limited evidence suggests that e-cigarettes are probably safer than tobacco smoke. A 2013 review found, from limited data, their safety risk is similar to that of smokeless tobacco. Due to various methodological issues, severe conflicts of interest, and inconsistent research, no definite conclusions can be determined regarding the safety e-cigarettes. However, e-cigarettes cannot be regarded as simply harmless. 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."

Scientific studies advocate caution before designating e-cigarettes as beneficial but vapers continue to believe they are beneficial. Many users assume that e-cigarettes are healthier than traditional cigarettes for personal use or for other people. Generally, some users are concerned about the possible adverse health effects or toxicity of e-cigarettes. The lack of research on the risks and possible benefits has resulted in precautionary policymaking in the U.S.

A 2015 Public Health England report stated that e-cigarettes are estimated to be 95% less harmful than smoking. In August 2014, the Forum of International Respiratory Societies stated that e-cigarettes have not been demonstrated to be safe. In the UK a National Institute for Health and Care Excellence (NICE) guideline did not recommend e-cigarettes as they are questions regarding the safety, efficacy, and quality of these products. 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." In 2014, the American Medical Association "called for reining in the sale and marketing practices of companies that produce electronic nicotine delivery systems" to minors.

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." 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." 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. E-cigarettes may be particularly appealing to youth due to their high-tech design, wide array of available flavors, including candy-and fruit-flavored cartridges, and easy availability online and in shopping malls. Because in nearly all jurisdictions they are not taxed as tobacco products, e-cigarettes may be more easily obtained by price-sensitive youth." The American Diabetes Association states "There is no evidence that e-cigarettes are a healthier alternative to smoking." Health Canada has stated that, "their safety, quality, and efficacy remain unknown." 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." The Canadian Heart and Stroke Foundation has stated, "Marketing and promotion of e-cigarettes is common. Youth are targeted with the addition of attractive candy or fruit flavours."

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." The Cancer Council Australia and Heart Foundation released a joint position statement that stated, "The limited evidence available points to a risk that widespread electronic cigarette use could undo the decades of public policy work in Australia that has reduced the appeal of cigarette use in children. Already there are anecdotal reports of electronic cigarettes being confiscated in Australian schools." The Cancer Society of New Zealand released a position statement which states, "E-cigarettes are a novelty product, which look like cigarettes. They are also marketed in a similar way, and come in candy-like flavours, such as chocolate and fruit,which may appeal to and encourage young people to try these products." The Spanish Society of Pneumonology and Thoracic Surgery (SEPAR) released a position statement which states that "indiscriminate use" of e-cigarettes is a public health risk and they may encourage young people to start smoking. The health effects on intensive e-cigarette users are unknown.

Adverse effects

A 2014 Cochrane review found no serious adverse effects from e-cigarette have been reported in trials. Reports to the Food and Drug Administration (FDA) for minor adverse effects identified with using e-cigarettes include headache, chest pain, nausea, and cough. Major adverse effects reported to the FDA included hospitalizations for pneumonia, congestive heart failure, seizure, rapid heart rate, and burns. However no direct relationship has been proven between these effects and e-cigarette use, and some of them may be due to health problems that were present before. Less serious adverse effects include throat and mouth inflammation, vomiting, nausea, and cough occur from e-cigarette use. Short-term adverse effects include mouth and throat inflammation, dry cough, and nausea. Adverse effect are mostly associated with a short term of use, and their frequency was significantly lower after 52 weeks of use. Long-term studies regarding the effects of e-cigarettes after chronic exposure are unavailable.

Commonly reported risks from e-cigarette use include upper respiratory tract irritation, dry cough, dryness of the mucus membrane, nose bleeding, release of cytokines and pro-inflammatory mediators, allergic air way inflammation, reduced levels of exhaled nitric oxide, headache, dizziness, nervousness, insomnia, sleeplessness, nausea, vomiting, dry mouth, tongue sores, black tongue, gum bleeding, gingivitis, gastric burning, constipation, palpitation, chest pain, eye irritation, eye redness, eye dryness, may result in eye damage, altered bronchial gene expression, chance of lung cancer, shortness of breath, and shivering. 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. 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. 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. 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. The adverse effects of e-cigarettes on people with cancer is unknown. As of 2015, the short and long term effects from using e-cigarettes remain unclear.

In youth, e-cigarette use risks involve accidental nicotine exposure. In pediatric patients, accidental exposures include ingesting of e-liquids and inhaling of e-cigarette vapor; choking on e-cigarette components is also a potential hazard. Unregulated e-cigarettes can be a risk to young children. In the United States, a child died after ingesting liquid nicotine in 2014, as did another child in Israel in 2013. A 2014 editorial stated that e-cigarettes have concentrated liquids that are packed in colorful containers and combined with flavors that appear to be made to attract children. It was concluded that it is recommended that e-cigarettes be kept in a safe place, where children and pets do not have access them.

Poisoning associated with e-cigarettes may happen by ingestion, inhalation, or absorption. 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. A causal relationship between e-cigarettes and the reported adverse effects was not established with the exception of two severe outcomes in the United States: a death when an infant choked on the cartridges and burns when one blew up. In the United States the number of calls to poison control centers related to electronic cigarettes have increased between 2010 and 2014, such that they now represent 42% of reported cases due to either cigarettes and e-cigarettes up from 0.3%. These calls were in connection to both adults and children. E-cigarettes were associated with fewer adverse effects than nicotine patches. Calls to U.S. poison control centers related to e-cigarette exposures involved inhalations, eye exposures, skin exposures, and ingestion, in both adults and young children. 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. The majority of adverse effects reported were nausea, vomiting, dizziness and oral irritation.

Fires, explosions, and other battery-related malfunctions

Most e-cigarettes use lithium batteries, the improper use of which may result in accidents. 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. Some batteries are not well designed, are made with poor quality components, or have defects. Rare major injuries have occurred from battery malfunctions such as explosions and fires. This includes house and car fires and skin burns from the outcome of some of the explosions. The explosions resulted either through extended charging and use of unsuitable chargers or as a result of design flaws. The United States Fire Administration said that 25 fires and explosions were caused by e-cigarettes between 2009 and 2015. In 2015 a report commissioned by Public Health England concluded that the risks of fire from e-cigarettes "appear to be comparable to similar electrical goods"; UK fire service call-outs were rising, from 43 in 2013 to 62 in 2014.

After a review of fire safety issues, including two incidents in which fires were caused by e-cigarettes packed in checked luggage, the U.S. Federal Aviation Administration issued a safety alert to air carriers in January 2015 saying that e-cigarettes should not be allowed in checked baggage. Although they are permitted to be brought on board flights as carry-on belongings, in-flight use of e-cigarettes is prohibited in the U.S.

The International Civil Aviation Organization, a United Nations agency, also recommends prohibiting e-cigarettes in checked luggage. 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. It has been recommended that manufacturing quality standards be imposed in order to prevent such accidents. Some of the risks from e-cigarette use could probably be reduced by better product design and standards.

Risks related to e-liquid

There is a possibility of high levels of nicotine exposure, in regard to e-cigarette cartridges, from inhalation, ingestion, or skin contact while replacing or handling of the e-cigarette cartridges. This may be especially risky to children, pregnant women, and nursing mothers. Use-related concerns with e-liquids also include leaks or spills and contact with contaminants in the e-liquid. Because there is a lack of production standards and controls, the e-liquid cleanliness frequently is not dependable, and testing of some products has shown the existence of toxic substances. 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. This includes leaking cartridges, accidental contact with nicotine when changing cartridges, and potential of unintended overdose. 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."

Nicotine toxicity is a concern when e-cigarette solutions are swallowed intentionally by adults as a suicidal overdose. A man died in 2012 after injecting himself with nicotine liquid. An excessive amount of nicotine for an adult that is capable of being fatal is 0.5–1 mg/kg of body weight. A lethal dose for grownups is from 30 – 60 mg. The American Association of Poison Control Centers recorded 3,638 "exposure" incidents relating to liquid nicotine as of November 30, 2014. In mass doses, nicotine may result in nausea, vomiting, diarrhea, salivation, bradyarrhythmia, and possibly seizures and hypoventilation. A lot of the cartridges and the bottles of liquid are not child-resistant, and children may be attracted to the flavored liquids. The nicotine in e-liquid can be hazardous to infants. Even a portion of e-liquid may be lethal to a little child. In December 2014, a one-year-old child in Fort Plain, New York died after an accidental ingestion of nicotine liquid. An excessive amount of nicotine for a child that is capable of being fatal is 0.1–0.2 mg/kg of body weight. An accidental ingestion of only 6 mg may be lethal to children.

A number of early studies found the strength of nicotine in e-liquid was often inaccurately stated, but in 2015 a report commissioned by Public Health England noted that from more recent studies "Market competition seems to have led to improved standards as poorly labelled products are now less common and overall the labelling accuracy has improved". Most inaccurately-labelled examples contained less nicotine than stated.

Toxicology

Carcinogenicity

Concerns about the carcinogenicity of e-cigarettes arise from both nicotine and from other chemicals that may be in the vapor. 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. A 2014 Surgeon General of the United States report concluded that the single relevant randomized trial "does not indicate a strong role for nicotine in promoting carcinogenesis in humans, and clearly the risk, if any, is less than continued smoking". The report 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". Older types of nicotine replacement products have not been shown to be associated with cancer in the real world.

In 2009 the FDA found tobacco-specific nitrosamines (TSNAs), known cancer-causing agents, "in a small sample of cartridges from two leading brands". The tobacco specific impurities suspected of being harmful to humans were anabasine, myosmine, and β-nicotyrine. They were detected in a majority of the 18 cartridges tested. The amounts of TSNAs present were on par with a nicotine inhaler. The FDA's analysis also detected diethylene glycol, which is poisonous, in a single cartridge manufactured by Smoking Everywhere and nicotine in one cartridge claimed to be nicotine-free. This prompted the FDA to warn that e-cigarettes may present a health risk. While diethylene glycol was found in a cartridge tested in 2009 by the FDA, in 2011 researchers reviewed the data and noted that 15 other studies had failed to find any evidence of this chemical in e-cigarettes.

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. Further concerns were raised over inconsistent amounts of nicotine delivered when drawing on the device. They are similar in toxicity to other nicotine replacement products, but there is not enough data to draw conclusions. A 2014 review found higher levels of carcinogens and toxins than in an FDA-approved nicotine inhaler, suggesting that FDA-approved devices may deliver nicotine more safely. 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." 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: Appeal to children, especially when flavors like strawberry or chocolate are added to the cartridges." The chemicals and toxic substances included in e-cigarettes have not been completely disclosed and their safety is not guaranteed. 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." Few of the methods used to analyze the chemistry of e-cigarettes in the studies the review evaluated were validated. The later-generation and "hotter" e-cigarette devices could expose individuals to greater amounts of carcinogens.

Propylene glycol and other chemicals

The primary base ingredients of the liquid solution is propylene glycol and glycerin. Being exposed to propylene glycol may cause irritation to the eyes and respiratory tract. When propylene glycol is heated and aerosolized, it could produce propylene oxide, which the International Agency for Research on Cancer (IARC) states is probably carcinogenic to humans. The risk from the inhalation of propylene glycol and glycerin is probably low. Propylene glycol and glycerin have not been shown to be safe. The long-term effects of inhaled propylene glycol has not been studied. Some research states that propylene glycol emissions may cause respiratory irritation and raise the likelihood to develop asthma. To lessen the risks, many e-cigarettes companies are using purified water and glycerin instead of propylene glycol for aerosol production. The effects of inhaled glycerin are unknown. When heated at atypical higher temperatures, glycerol may generate harmful acrolein. Acrolein may induce irritation to the upper respiratory tract. Some e-cigarette products had acrolein identified in the aerosol. Acrolein levels were reduced by 60% in dual users and 80% for those that completely switched to e-cigarettes when compared to traditional cigarettes. 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.

The essential propylene glycol and/or glycerol mixture may consist of natural or artificial substances to provide it flavor. The cytotoxicity of e-liquids varies. Some flavors are regarded as toxic and a number of them resemble known carcinogens. Generally, flavoring additives are imprecisely described, using terms such as "vegetable flavoring". Although they are approved for human consumption there are no studies on the short- or long-term effects of inhaling them. Some artificial flavors have been demonstrated as being cytotoxic. The cytotoxicity is mostly due to the amount and number of flavors added. Cinnamaldehyde has been documented as a highly cytotoxic material in cinnamon-flavored refill solutions. Diacetyl and acetyl propionyl are correlated with respiratory disease if inhaled, which have been detected in flavored liquid solutions. A study has demonstrated that a balsamic flavored e-cigarette with no nicotine is capable of triggering a proinflammatory cytokine release in lung epithelial cells and keratinocytes. Some additives may be added to lower the irritation on the pharynx. The precise ingredients of e-cigarettes are not known. Butyl acetate, diethyl carbonate, benzoic acid, quinoline, and bis(2-ethylhexyl) phthalate have been found in e-cigarettes.

E-cigarettes have a few metal parts that come in contact with the e-liquid that contaminate it with metals. 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 that touches the liquid is heated. These compounds are frequently identified in e-cigarette aerosols. The propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette aerosols. The IARC has categorized formaldehyde as a human carcinogen, and acetaldehyde is categorized as a potential carcinogenic to humans. These materials may cause harmful health effects; though, in the majority of cases, the amounts inhaled are less than those in traditional cigarettes. A 2014 review found "most E-cigarettes contain large concentrations of propylene glycol, a known irritant when inhaled. Little is known about the health impact of long-term inhalation of propylene glycol. At high temperatures, propylene glycol can oxidize and form toxic compounds such as formaldehyde and acetaldehyde." Nearly all e-cigarettes evaluated, toxic and irritation-causing carbonyl substances were identified. This included formaldehyde, acetaldehyde, and acrolein. The majority of e-cigarettes evaluated included carcinogenic TSNAs; heavy metals such as cadmium, nickel, and lead; and the carcinogen toluene. However, in comparison to traditional cigarette smoke, the toxic substance levels identified in e-cigarette vapor were 9- to 450-fold less. "Dripping", where the liquid is dripped directly onto the atomizer, can create carbonyl compounds including formaldehyde. The levels of toxic substances in the vapor were found to be 1 to 2 orders of magnitude smaller than in cigarette smoke but greater than from a nicotine inhaler. It also has lower concentrations of potential toxic substances than cigarette smoke. While e-cigarettes with higher voltage batteries can produce carcinogens including formaldehyde at levels found in cigarette smoke, reduced voltage e-cigarettes produce vapor with levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than indicated in cigarette smoke. A 2015 review found vaping e-cigarettes at a high voltage (5.0V) may generate formaldehyde-forming chemicals at a greater level than smoking, which has been determined to be a lifetime cancer risk of about 5 to 15 times greater than smoking; the underlying research had used a "puffing machine". Another small study with people using similar devices and settings found that the users could not use the devices because of "dry-puffs" at the high settings, which according to the 2015 Public Health England report "poses no danger to either experienced or novice vapers, because dry puffs are aversive and are avoided rather than inhaled" and "At normal settings, there was no or negligible formaldehyde release." They concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."

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. Users may alter many of the devices, such as using them to administer other drugs like cannabis. Battery output voltage influences the level of the carbonyl substances in the vapor. A few new e-cigarettes let users boost the amount of vapor and nicotine provided by modifying the battery output voltage. For example, a study demonstrated "that increasing the voltage from 3.2–4.8 V resulted in a 4 to >200 times increase in the formaldehyde, acetaldehyde, and acetone levels." Thus, high-voltage e-cigarettes is capable of subjecting users to large amounts of carbonyl substances. Reduced voltage e-cigarettes had e-cigarette aerosol levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than indicated in traditional cigarette smoke. Devices using higher voltages can produce carcinogens including formaldehyde at levels found in cigarette smoke. Vaping e-cigarettes at high voltage (5.0V) may generate formaldehyde-forming chemicals at a greater level than smoking, which has been determined to be a lifetime cancer risk of about 5 to 15 times greater than smoking. A Public Health England report found "At normal settings, there was no or negligible formaldehyde release." They concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes." 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. There is no long-term research concerning the cancer risk related to the small level of exposure to the identified carcinogens. The short-term toxicity of e-cigarette use appears to be low, with the exception for some people with reactive airways. The long-term health impacts of e-cigarette use are unknown. The long-term toxicity is subject to the additives and contaminants in the e-liquid. There is limited peer-reviewed data about the toxicity of e-cigarettes for a complete toxicological evaluation. The cytotoxicity from using e-cigarettes is unknown.

Nicotine

Nicotine is regarded as a potentially lethal poison. Concerns exist that e-cigarette user exposure to toxic levels of nicotine may be harmful. Research suggests that experienced e-cigarettes users are able to get as much nicotine from e-cigarettes as traditional cigarettes. The levels were above that of nicotine replacement product users. Other research have demonstrated that 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. 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. How efficiently different e-cigarettes give nicotine is unclear. Later-generation e-cigarettes gives nicotine more effectively than first generation e-cigarettes. Studies suggest that inexperienced users obtain moderate amounts of nicotine from e-cigarettes. Later-generation e-cigarettes with more concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes. E-cigarettes with stronger batteries heat solutions to higher temperatures, which may raise blood nicotine levels to those of traditional cigarettes. Since nicotine-containing e-liquids are made from tobacco they may contain impurities like cotinine, anabasine, anatabine, myosmine and beta-nicotyrine.

Serum nicotine levels identified are inharmonious and rely upon the user and the device. Although some e-cigarettes are nicotine free, surveys demonstrate that 97% of e-cigarette users use products that contain nicotine. There was inconsistent labeling of the actual nicotine content on e-liquid cartridges from some brands. Some nicotine has been found in ‘no nicotine' liquids. Due to nicotine content inconstancy, it is recommended that e-cigarette companies develop quality standards with respect to nicotine content. Serum cotinine levels are comparable to that of traditional cigarettes. The nicotine delivered from e-cigarettes enters the body slower than traditional cigarettes. E-cigarettes provide nicotine to the blood quicker than nicotine inhalers.

The long-term health impacts of the main chemicals nicotine and propylene glycol in the aerosol are not fully understood. Nicotine affects practically every cell in the body. There are safety issues with the nicotine exposure from e-cigarettes, which may cause addiction and other adverse effects. Nicotine can cause high blood pressure and abnormal heart rhythms. Nicotine may have adverse effects on lipids. Nicotine lowers estrogen levels and has been associated with early menopause in women. 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." Nicotine could have cancer-promoting proprieties, therefore long-term use may not be harmless. Nicotine may result in neuroplasticity variations in the brain. In youth, nicotine may affect brain development, later achievement, as well as the chance of nicotine addiction for life. Nicotine use during adolescence may damage brain development, including capabilities connected with higher cognitive function processes. The Centers for Disease Control and Prevention (CDC) stated the possible negative effect of nicotine on brain development in youth is a concern. In August 2014, the American Heart Association released a policy statement in which they noted that "e-cigarettes could fuel and promote nicotine addiction, especially in children, and their acceptance has the potential to renormalize smoking behavior." The health effects of nicotine in infants and children are unclear.

Effects on breathing and lung function

A 2013 review found an instant increase in airway resistance after using a single e-cigarette, and concluded that they can harm the respiratory system. The risks, especially to the lungs, are not fully understood and are of concern to public health authorities. About 20% to 27% of propylene glycol and glycerin-based liquid particles are inhaled. The particles are of the ultrafine size which can go deep in the lungs and then into the systemic circulation. Reports in the literature have shown respiratory and cardiovascular effects by these smaller size particles, suggesting a possible health concern. The device itself could contribute to the toxicity from the tiny amounts of silicate and heavy metals found in the liquid and vapor. 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. A 2014 review found e-cigarettes emissions contain the heavy metals nickel, tin, and chromium. These nanoparticles can deposit in the lung's alveolar sacs, potentially leading to local respiratory toxicity and entering the bloodstream. A 2014 review found considerable amounts of tin, metals, and silicate beads that came from various components of the e-cigarette were detected in the aerosol, which may result in exposure that could be higher than a traditional cigarette. Metals may adversely affect the nervous system. A 2014 review found it can be concluded that there is no evidence of contamination of the aerosol with metals that justifies a health concern. A 2014 review noted a study had found metal particles in the fluid and aerosol, however that study did not evaluate the relevance of the levels identified. The same review found that these levels were 10-50 times less than that allowed in medicines that are inhaled. Reports on the levels of toxicants in the emissions are inconsistent. There is limited evidence on the long-term exposure of metals. There is limited evidence on the long-term health effects to the lungs. The effects of e-cigarette use in respect to asthma and other respiratory diseases are unknown.

E-cigarettes companies assert that the particulates produced by an e-cigarette are too tiny to be deposited in the alveoli but the carcinogens identified in an e-cigarette include nitrosamines, di-ethylene glycol, acetaldehyde, and other toxins such as mercury, anabasine, myosmineand beta-nicotyrine. Comparable to a traditional cigarette, e-cigarette particles are tiny enough to enter the alveoli, enabling nicotine absorption. The immediate effects of e-cigarettes after 5 minutes of use on pulmonary function resulted in considerable increases in resistance to lung airflow. Short-term physiological effects include increases in blood pressure and heart rate. A 2014 review found that tests of cardiovascular and respiratory functions after short-term use of e-cigarettes demonstrated some harmful effects of vaping, but these were appreciably milder in comparison to traditional cigarettes. When used in the short-term, an e-cigarette results in a rise of respiratory resistance comparatively to traditional cigarettes. The long-term effects regarding respiratory flow resistance are unknown.

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. This is due to the minute nicotine particles in the vapor, which permit quick delivery into the bloodstream. This 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. Some case reports documented the possible cardiovascular adverse effects from using e-cigarettes, the majority associated was with improper use. Even though e-cigarettes are anticipated to produce fewer dangerous substances than traditional cigarettes, limited evidence supports they comparatively have a lessened raised cardiovascular risk for e-cigarettes users. The limited evidence suggests that e-cigarettes produce less short-term effects on lung function than traditional cigarettes. Like cancer risk, there is no literature outlining the long-term lung function or cardiovascular consequences. 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. A 2015 review found e-cigarettes may induce acute lung disease. The effect on population health from e-cigarettes is unknown.

Ultrafine particles

E-cigarettes produce particles, in the form of an aerosol. The aerosol (mist) produced by an e-cigarette is commonly but inaccurately called vapor. 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. The word "vaping" is not technically accurate when applied to e-cigarettes. The aerosol is made-up of liquid sub-micron particles of condensed vapor; thus, the users of these devices are rather "aerosolizing." The aerosol the e-cigarette produces resembles cigarette smoke. A 2014 review found "Following a puff, the aerosol is delivered into the user's mouth and lungs by inhalation, after which the remaining aerosol is exhaled into the environment." E-cigarettes provide nicotine by creating liquid particles. E-cigarette vapor mostly consist of propylene glycol, glycerol, water, flavorings, nicotine, and other chemicals. Exactly what comprises the vapor varies in composition and concentration across and within manufacturers.

A 2014 review found that fine particles can be chemically intricate and not uniform, and what a particle is made of, the exact harmful elements, and the importance of the size of the particle is mostly unknown. They found that because these things are uncertain, it is not clear whether the ultrafine particles in e-cigarette vapor have health effects similar to those produced by traditional cigarettes. Emissions from electronic cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different, although a 2014 review found that 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 (modes, ≈100–200). The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled. Different devices generate different particle sizes and cause different depositions in the respiratory tract, even from the same nicotine liquid. A 2014 review found that the aerosol particle concentration is 5 times lower from an e-cigarette than from a traditional cigarette. A 2014 WHO report found e-cigarettes release a lower level of particles than traditional cigarettes. A 2014 review found that the density of particles in the vapor is lower than in cigarette smoke by a factor of between 6 and 880 times lower.

A 2015 review found that for particulate matter emissions, e-cigarettes slightly exceeded the WHO guidelines, but emissions were 15 times less than traditional cigarette use.

Effects on bystanders

There is insufficient data to determine the impact on public health from e-cigarettes. The potential harm to bystanders from e-cigarettes is unknown. This is because no long-term data is available. A white paper published in 2014 by the American Industrial Hygiene Association concluded e-cigarettes emit airborne contaminants that may be inhaled by the user and those nearby. Due to this possible risk, they urged restriction of their use indoors, similar to smoking bans, until research has shown the aerosol does not significantly harm others in the area. A 2014 review indicated that the levels of inhaled contaminants from the e-cigarette vapor are not of significant health concern for human exposures by the standards used in workplaces to ensure safety. The British Medical Association (BMA) reported in 2013 that there are "concerns that the use of e-cigarettes could threaten the norm of not smoking in public places and workplaces." The use of e-cigarettes in a smoke-free area could expose non-users to toxins. The effect on bystanders would likely be much less harmful than traditional cigarettes. In 2015 a report commissioned by Public Health England concluded that e-cigarettes "release negligible levels of nicotine into ambient air with no identified health risks to bystanders".

Since e-cigarettes do not burn (or contain) tobacco, no side-stream smoke or any cigarette smoke is produced. Only what is exhaled by e-cigarettes users enters the surrounding air. Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted. Thus, cardiocirculatory effects caused by carbon monoxide are not likely. However, in an experimental study, e-cigarettes increased levels of carcinogenic polycyclic aromatic hydrocarbons in the surrounding air. There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors. Passive inhalation of vapor might have significant adverse effects. However, it has been demonstrated that e-cigarettes causes nonusers to be exposed to nicotine but not to tobacco-related combustion toxicants. E-cigarettes used in indoor environments can put at risk nonsmokers to elevated levels of nicotine and aerosol emissions. Nonsmokers exposed to e-cigarette aerosol produced by a machine and pumped into a room were found to have detectable levels of the nicotine metabolite cotinine in their blood. The same study stated that 80% of nicotine is normally absorbed by the user, so these results may be higher than in actual second hand exposure. A 2014 review of limited data concluded this vapor can cause indoor air pollution and is not just "water vapor" as is frequently stated in the advertising of e-cigarettes. E-cigarette use by a parent might lead to inadvertent health risks to offspring.

E-cigarettes are marketed as "free of primary and second-hand smoke risk" due to no carbon monoxide or tar is expected to be generated during use. However, there is a concern for the health impact of nicotine and other added ingredients. Exhaled vapor consists of nicotine and some other particles, primarily consisting of flavors, aroma transporters, glycerin and propylene glycol. Bystanders are exposed to these particles from exhaled e-cigarette vapor. A mixture of harmful substances, particularly nicotine, ultrafine particles, and volatile organic compounds can be exhaled into the air. The dense vapor consists of liquid sub-micron droplets. The liquid particles condenses into a viewable fog. The vapor is in the air for a short time, with a half-life of about 10 seconds; traditional cigarette smoke is in the air 100 times longer. This is because of fast revaporization at room temperature. Some of the few studies examining the effects on health shown that being exposed to e-cigarette vapor may produce biological effects. Since e-cigarettes have not been widely used long enough for evaluation, the long-term health effects from the second-hand vapor are not known. The 2015 California Department of Public Health has reported that "Mainstream and secondhand e-cigarette aerosol has been found to contain at least ten chemicals that are on California’s Proposition 65 list of chemicals known to cause cancer, birth defects, or other reproductive harm." 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."

As of 2013, the only clinical study currently published evaluating the respiratory effects of passive vaping found no adverse effects were detected. A 2014 review found it is safe to infer that their effects on bystanders are minimal in comparison to traditional cigarettes. A 2014 WHO report stated passive exposure was as a concern, indicating that current evidence is insufficient to determine whether the levels of exhaled vapor are safe to involuntarily exposed bystanders. The report stated that "it is unknown if the increased exposure to toxicants and particles in exhaled aerosol will lead to an increased risk of disease and death among bystanders." E-cigarette vapor has notably fewer toxicants than cigarette smoke and is likely to pose less harm to users or bystanders. A 2014 practice guideline by NPS MedicineWise states, "Although data on health effects of passive vapour are currently lacking, the risks are argued to be small, but claims that e-cigarettes emit only water vapour are nevertheless incorrect. Serum cotinine levels (a metabolite of nicotine) have been found to be similar in bystanders exposed to either e-cigarette vapour or cigarette smoke."

E-cigarettes pose many safety concerns to children. 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. A policy statement by the American Association for Cancer Research and the American Society of Clinical Oncology has reported that "Third-hand exposure occurs when nicotine and other chemicals from second-hand aerosol deposit on surfaces, exposing people through touch, ingestion, and inhalation". Nicotine is actually hard to get rid of from surfaces. The statement noted there are no published studies of third hand exposure from e-cigarettes, however initial data suggests that nicotine from e-cigarettes may stick to surfaces. In January 2014, the International Union Against Tuberculosis and Lung Disease stated "Adverse health effects for exposed third parties (second-hand exposure) cannot be excluded because the use of electronic cigarettes leads to emission of fine and ultrafine inhalable liquid particles, nicotine and cancer-causing substances into indoor air."

Effects during pregnancy

A 2014 review stated there are concerns about pregnant women exposure to e-cigarette vapor through direct use or via exhaled vapor. As of 2014, 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. A 2015 review concluded no amount of nicotine is safe for pregnant women. E-cigarette are assumed to be dangerous to the fetus during pregnancy if e-cigarettes are used by the mother. Prenatal exposure has been associated with obesity, diabetes, high cholesterol and high blood pressure in minors. As of 2015, the long-term issues of e-cigarettes on both mother and unborn baby are unknown. There are concerns about the health impacts of pediatric exposure to second-hand and third-hand e-cigarette vapor. 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." The belief that e-cigarettes are safer than traditional cigarettes could increase their use for pregnant women. The toxic effects identified with e-cigarette refill liquids on stem cells may be interpreted as embryonic death or birth defects. 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.

Environmental impact

There is limited information available on any environmental issues connected to the production, usage, and disposal of e-cigarette models that use cartridges. No formal studies have been done to evaluate the environmental effects of making or disposing of any part of an e-cigarettes including the batteries or nicotine production. As of 2014, it is uncertain if the nicotine in e-liquid is United States Pharmacopeia-grade nicotine, a tobacco extract, or a synthetic nicotine when questioning the environmental impact of how it is made. It is not clear which manufacturing methods are used to make the nicotine used in e-cigarettes. The emissions from making nicotine could be considerable from manufacturing if not appropriately controlled. Some e-cigarette brands that use cartridges state their products are ‘eco-friendly’ or ‘green’, despite the absence of any supporting studies. Some writers contend that such marketing may raise sales and increase e-cigarette interest, particularly among minors. It is unclear how many traditional cigarettes are comparable to using one e-cigarette that uses a cartridge for the average user. Information is limited on energy and materials used for production of e-cigarettes versus traditional cigarettes, for comparable use. E-cigarettes can be made manually put together in small factories, or they can be made in automated lines on a much bigger scale. Larger plants will produce greater emissions to the surrounding environment, and thus will have a greater environmental impact. Although some brands have begun recycling services for their e-cigarette cartridges, the prevalence of recycling is unknown, as is the prevalence of information provided by manufacturers on how to recycle disposable parts. Some brands have also begun recycling services for their e-cigarette batteries. A 2014 review found "disposable e-cigarettes might cause an electrical waste problem."

Public perceptions

The UK Action on Smoking and Health 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". 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." The charity 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."

A 2015 Public Health England report noted, as well as the UK figures above, that in the US belief among responders to a survey that vaping was safer than smoking cigarettes fell from 82% in 2010 to 51% in 2014. 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".

See also

• Regulation of electronic cigarettes
• Positions of medical organizations on electronic cigarettes

References

1. Caponnetto, Pasquale; Campagna, Davide; Papale, Gabriella; Russo, Cristina; Polosa, Riccardo (2012). "The emerging phenomenon of electronic cigarettes". Expert Review of Respiratory Medicine. 6 (1): 63–74. doi:10.1586/ers.11.92. ISSN 1747-6348. PMID 22283580.
2. "The Potential Adverse Health Consequences of Exposure to Electronic Cigarettes and Electronic Nicotine Delivery Systems". Oncology Nursing Forum. 42 (5): 445–446. 2015. doi:10.1188/15.ONF.445-446. ISSN 0190-535X. PMID 26302273.
3. ^ Ebbert, Jon O.; Agunwamba, Amenah A.; Rutten, Lila J. (2015). "Counseling Patients on the Use of Electronic Cigarettes". Mayo Clinic Proceedings. 90 (1): 128–134. doi:10.1016/j.mayocp.2014.11.004. ISSN 0025-6196. PMID 25572196.
4. Harrell, PT; Simmons, VN; Correa, JB; Padhya, TA; Brandon, TH (4 June 2014). "Electronic Nicotine Delivery Systems ("E-cigarettes"): Review of Safety and Smoking Cessation Efficacy". Otolaryngology—head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery. 151: 381–393. doi:10.1177/0194599814536847. PMID 24898072.
5. Odum, L. E.; O'Dell, K. A.; Schepers, J. S. (December 2012). "Electronic cigarettes: do they have a role in smoking cessation?". Journal of pharmacy practice. 25 (6): 611–4. doi:10.1177/0897190012451909. PMID 22797832.
6. ^ Grana, R; Benowitz, N; Glantz, SA (13 May 2014). "E-cigarettes: a scientific review". Circulation. 129 (19): 1972–86. doi:10.1161/circulationaha.114.007667. PMC 4018182. PMID 24821826.
7. O'Connor, RJ (March 2012). "Non-cigarette tobacco products: what have we learnt and where are we headed?". Tobacco control. 21 (2): 181–90. doi:10.1136/tobaccocontrol-2011-050281. PMC 3716250. PMID 22345243.
8. Golub, Justin S.; Samy, Ravi N. (2015). "Preventing or reducing smoking-related complications in otologic and neurotologic surgery". Current Opinion in Otolaryngology & Head and Neck Surgery. 23 (5): 334–340. doi:10.1097/MOO.0000000000000184. ISSN 1068-9508. PMID 26339963.
9. ^ McNeill, A, SC (2015). "E - cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. p. 76. Retrieved 19 August 2015.{{cite web}}: CS1 maint: multiple names: authors list (link)
10. ^ Cooke, Andrew; Fergeson, Jennifer; Bulkhi, Adeeb; Casale, Thomas B. (2015). "The Electronic Cigarette: The Good, the Bad, and the Ugly". The Journal of Allergy and Clinical Immunology: In Practice. 3 (4): 498–505. doi:10.1016/j.jaip.2015.05.022. ISSN 2213-2198. PMID 26164573.
11. ^ Orellana-Barrios, Menfil A.; Payne, Drew; Mulkey, Zachary; Nugent, Kenneth (2015). "Electronic cigarettes-a narrative review for clinicians". The American Journal of Medicine. doi:10.1016/j.amjmed.2015.01.033. ISSN 0002-9343. PMID 25731134.
12. ^ Bekki, Kanae; Uchiyama, Shigehisa; Ohta, Kazushi; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki (2014). "Carbonyl Compounds Generated from Electronic Cigarettes". International Journal of Environmental Research and Public Health. 11 (11): 11192–11200. doi:10.3390/ijerph111111192. ISSN 1660-4601. PMID 25353061.{{cite journal}}: CS1 maint: unflagged free DOI (link)
13. ^ McNeill, A, SC (2015). "E – cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. pp. 77–78.{{cite web}}: CS1 maint: multiple names: authors list (link) Cite error: The named reference "McNeill201577" was defined multiple times with different content (see the help page).
14. ^ Caponnetto P; Russo C; Bruno CM; Alamo A; Amaradio MD; Polosa R. (Mar 2013). "Electronic cigarette: a possible substitute for cigarette dependence". Monaldi archives for chest disease. 79 (1): 12–19. PMID 23741941.
15. ^ Drummond, MB; Upson, D (February 2014). "Electronic cigarettes. Potential harms and benefits". Annals of the American Thoracic Society. 11 (2): 236–42. doi:10.1513/annalsats.201311-391fr. PMID 24575993.
16. ^ Bertholon, J.F.; Becquemin, M.H.; Annesi-Maesano, I.; Dautzenberg, B. (2013). "Electronic Cigarettes: A Short Review". Respiration. 86: 433–8. doi:10.1159/000353253. ISSN 1423-0356. PMID 24080743.
17. ^ Farsalinos, K. E.; Polosa, R. (2014). "Safety evaluation and risk assessment of electronic cigarettes as tobacco cigarette substitutes: a systematic review". Therapeutic Advances in Drug Safety. 5 (2): 67–86. doi:10.1177/2042098614524430. ISSN 2042-0986. PMC 4110871. PMID 25083263.
18. ^ Hajek, P; Etter, JF; Benowitz, N; Eissenberg, T; McRobbie, H (31 July 2014). "Electronic cigarettes: review of use, content, safety, effects on smokers and potential for harm and benefit" (PDF). Addiction (Abingdon, England). 109 (11): 1801–10. doi:10.1111/add.12659. PMID 25078252.
19. ^ Cheng, T. (2014). "Chemical evaluation of electronic cigarettes". Tobacco Control. 23 (Supplement 2): ii11–ii17. doi:10.1136/tobaccocontrol-2013-051482. ISSN 0964-4563. PMC 3995255. PMID 24732157.
20. ^ Pisinger, Charlotta; Døssing, Martin (December 2014). "A systematic review of health effects of electronic cigarettes". Preventive Medicine. 69: 248–260. doi:10.1016/j.ypmed.2014.10.009. PMID 25456810.
21. ^ Durmowicz, E. L. (2014). "The impact of electronic cigarettes on the paediatric population". Tobacco Control. 23 (Supplement 2): ii41–ii46. doi:10.1136/tobaccocontrol-2013-051468. ISSN 0964-4563. PMID 24732163.
22. ^ Rowell, Temperance R; Tarran, Robert (2015). "Will Chronic E-Cigarette Use Cause Lung Disease?". American Journal of Physiology - Lung Cellular and Molecular Physiology: ajplung.00272.2015. doi:10.1152/ajplung.00272.2015. ISSN 1040-0605. PMID 26408554.
23. ^ WHO. "Electronic nicotine delivery systems" (PDF). pp. 1–13. Retrieved 28 August 2014.
24. ^ Fernández, Esteve; Ballbè, Montse; Sureda, Xisca; Fu, Marcela; Saltó, Esteve; Martínez-Sánchez, Jose M. (2015). "Particulate Matter from Electronic Cigarettes and Conventional Cigarettes: a Systematic Review and Observational Study". Current Environmental Health Reports. doi:10.1007/s40572-015-0072-x. ISSN 2196-5412. PMID 26452675.
25. ^ Rom, Oren; Pecorelli, Alessandra; Valacchi, Giuseppe; Reznick, Abraham Z. (2014). "Are E-cigarettes a safe and good alternative to cigarette smoking?". Annals of the New York Academy of Sciences. 1340 (1): 65–74. doi:10.1111/nyas.12609. ISSN 0077-8923. PMID 25557889.
26. ^ England, Lucinda J.; Bunnell, Rebecca E.; Pechacek, Terry F.; Tong, Van T.; McAfee, Tim A. (2015). "Nicotine and the Developing Human". American Journal of Preventive Medicine. doi:10.1016/j.amepre.2015.01.015. ISSN 0749-3797. PMID 25794473.
27. ^ "Electronic cigarettes: patterns of use, health effects, use in smoking cessation and regulatory issues". Tob Induc Dis. 12 (1): 21. 2014. doi:10.1186/1617-9625-12-21. PMC 4350653. PMID 25745382. {{cite journal}}: Unknown parameter |authors= ignored (help)CS1 maint: unflagged free DOI (link)
28. ^ McRobbie, Hayden; Bullen, Chris; Hartmann-Boyce, Jamie; Hajek, Peter; McRobbie, Hayden (2014). "Electronic cigarettes for smoking cessation and reduction". The Cochrane Library. 12: CD010216. doi:10.1002/14651858.CD010216.pub2. PMID 25515689.
29. ^ "E-cigarettes: Safe to recommend to patients?". Cleve Clin J Med. 82 (8): 521–6. 2015. doi:10.3949/ccjm.82a.14054. PMID 26270431. {{cite journal}}: Unknown parameter |authors= ignored (help)
30. ^ "The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General, 2014, Chapter 5 - Nicotine" (PDF). Surgeon General of the United States. 2014. pp. 107–138.
31. ^ Saitta, D; Ferro, GA; Polosa, R (Mar 2014). "Achieving appropriate regulations for electronic cigarettes". Therapeutic advances in chronic disease. 5 (2): 50–61. doi:10.1177/2040622314521271. PMC 3926346. PMID 24587890.
32. ^ Chang, H. (2014). "Research gaps related to the environmental impacts of electronic cigarettes". Tobacco Control. 23 (Supplement 2): ii54–ii58. doi:10.1136/tobaccocontrol-2013-051480. ISSN 0964-4563. PMC 3995274. PMID 24732165.
33. ^ Dagaonkar RS, R.S.; Udwadi, Z.F. (2014). "Water pipes and E-cigarettes: new faces of an ancient enemy" (PDF). Journal of the Association of Physicians of India. 62 (4): 324–328. PMID 25327035.
34. ^ Cervellin, Gianfranco; Borghi, Loris; Mattiuzzi, Camilla; Meschi, Tiziana; Favaloro, Emmanuel; Lippi, Giuseppe (2013). "E-Cigarettes and Cardiovascular Risk: Beyond Science and Mysticism". Seminars in Thrombosis and Hemostasis. 40 (01): 060–065. doi:10.1055/s-0033-1363468. ISSN 0094-6176. PMID 24343348.
35. ^ Brandon, T. H.; Goniewicz, M. L.; Hanna, N. H.; Hatsukami, D. K.; Herbst, R. S.; Hobin, J. A.; Ostroff, J. S.; Shields, P. G.; Toll, B. A.; Tyne, C. A.; Viswanath, K.; Warren, G. W. (2015). "Electronic Nicotine Delivery Systems: A Policy Statement from the American Association for Cancer Research and the American Society of Clinical Oncology". Clinical Cancer Research. 21: 514–525. doi:10.1158/1078-0432.CCR-14-2544. ISSN 1078-0432. PMID 25557889.
36. ^ Pepper, J. K.; Brewer, N. T. (2013). "Electronic nicotine delivery system (electronic cigarette) awareness, use, reactions and beliefs: a systematic review". Tobacco Control. 23 (5): 375–384. doi:10.1136/tobaccocontrol-2013-051122. ISSN 0964-4563. PMID 24259045.
37. "A review of the current geographic distribution of and debate surrounding electronic cigarette clean air regulations in the United States". Health Place. 31C: 75–82. 2015. doi:10.1016/j.healthplace.2014.11.003. PMID 25463920. {{cite journal}}: Unknown parameter |authors= ignored (help)
38. &NA; (August 2014). "E-Cigarettes". Oncology Times. 36 (15): 49–50. doi:10.1097/01.COT.0000453432.31465.77.{{cite journal}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)
39. "Nicotine products can help people to cut down before quitting smoking". National Institute for Health and Care Excellence.
40. "RCP statement on e-cigarettes". Royal College of Physicians. 25 June 2014.
41. "AMA Strengthens Position on Regulation of Electronic Cigarettes". AMA. 10 June 2014.
42. "What about electronic cigarettes? Aren't they safe?". American Cancer Society.
43. "E-Cigarettes". Tobacco Control Research Branch of the National Cancer Institute.
44. "Regulation of Electronic Cigarettes ("E-Cigarettes")" (PDF). National Association of County and City Health Officials.
45. "Standards of Medical Care in Diabetes--2015: Summary of Revisions". Diabetes Care. 54 (38): S25. 2015. doi:10.2337/dc15-S003.
46. "Nicotine addiction". Health Canada.
47. "Ways to quit". Canadian Cancer Society.
48. "Heart and Stroke Foundation: E-cigarettes in Canada". Heart and Stroke Foundation.
49. "Stop smoking treatments". UK National Health Service.
50. "Position Statement Electronic Cigarettes". Cancer Council Australia, Heart Foundation.
51. "Position Statement on Electronic Cigarettes" (PDF). Cancer Society of New Zealand.
52. ^ Jimenez Ruiz, CA; Solano Reina, S; de Granda Orive, JI; Signes-Costa Minaya, J; de Higes Martinez, E; Riesco Miranda, JA; Altet Gómez, N; Lorza Blasco, JJ; Barrueco Ferrero, M; de Lucas Ramos, P (August 2014). "The electronic cigarette. Official statement of the Spanish Society of Pneumology and Thoracic Surgery (SEPAR) on the efficacy, safety and regulation of electronic cigarettes". Archivos de bronconeumologia. 50 (8): 362–7. doi:10.1016/j.arbr.2014.06.007. PMID 24684764.
53. Detailed reference list is located on a separate image page.
54. ^ Gualano, M. R.; Passi, S.; Bert, F.; La Torre, G.; Scaioli, G.; Siliquini, R. (9 August 2014). "Electronic cigarettes: assessing the efficacy and the adverse effects through a systematic review of published studies". Journal of Public Health. doi:10.1093/pubmed/fdu055. PMID 25108741.
55. ^ SA, Meo; SA, Al Asiri (2014). "Effects of electronic cigarette smoking on human health" (PDF). Eur Rev Med Pharmacol Sci. 18 (21): 3315–9. PMID 25487945.
56. Lauterstein, Dana; Hoshino, Risa; Gordon, Terry; Watkins, Beverly-Xaviera; Weitzman, Michael; Zelikoff, Judith (2014). "The Changing Face of Tobacco Use Among United States Youth". Current Drug Abuse Reviews. 7 (1): 29–43. doi:10.2174/1874473707666141015220110. ISSN 1874-4737. PMID 25323124.
57. Evans, S. E.; Hoffman, A. C. (2014). "Electronic cigarettes: abuse liability, topography and subjective effects". Tobacco Control. 23 (Supplement 2): ii23–ii29. doi:10.1136/tobaccocontrol-2013-051489. ISSN 0964-4563. PMID 24732159.
58. ^ Crowley, Ryan A. (2015). "Electronic Nicotine Delivery Systems: Executive Summary of a Policy Position Paper From the American College of Physicians". Annals of Internal Medicine. 162 (8): 583. doi:10.7326/M14-2481. ISSN 0003-4819. PMID 25894027.
59. ^ Biyani, S; Derkay, CS (28 April 2015). "E-cigarettes: Considerations for the otolaryngologist". International journal of pediatric otorhinolaryngology. doi:10.1016/j.ijporl.2015.04.032. PMID 25998217.
60. ^ McKee, M. (2014). "Electronic cigarettes: peering through the smokescreen". Postgraduate Medical Journal. 90 (1069): 607–609. doi:10.1136/postgradmedj-2014-133029. ISSN 0032-5473. PMID 25294933.
61. "Poison Center Calls Involving E-Cigarettes". CDC.
62. ^ Orr, KK; Asal, NJ (November 2014). "Efficacy of Electronic Cigarettes for Smoking Cessation". The Annals of pharmacotherapy. 48 (11): 1502–1506. doi:10.1177/1060028014547076. PMID 25136064.
63. Centers for Disease Control and Prevention (CDC) (April 2014). "Notes from the field: calls to poison centers for exposures to electronic cigarettes--United States, September 2010-February 2014". MMWR Morb. Mortal. Wkly. Rep. 63 (13): 292–3. PMID 24699766.
64. ^ Jansen, Bart, "Packing e-Cigarettes in luggage is a fire risk, FAA warns", USA Today, January 23, 2015.
65. McNeill, A, SC (2015). "E - cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. Retrieved 20 August 2015.{{cite web}}: CS1 maint: multiple names: authors list (link), pages 83-84. 43/46 UK fire services responded, 2014 figures are for 1 January to 15 November only.
66. ^ Hasley III, Ashley, "The FAA wants you to carry on your e-Cigs", The Washington Post, January 26, 2015.
67. ^ Yang, L.; Rudy, S. F.; Cheng, J. M.; Durmowicz, E. L. (2014). "Electronic cigarettes: incorporating human factors engineering into risk assessments". Tobacco Control. 23 (Supplement 2): ii47–ii53. doi:10.1136/tobaccocontrol-2013-051479. ISSN 0964-4563. PMID 24732164.
68. ^ Brown, C. J.; Cheng, J. M. (2014). "Electronic cigarettes: product characterisation and design considerations". Tobacco Control. 23 (Supplement 2): ii4–ii10. doi:10.1136/tobaccocontrol-2013-051476. ISSN 0964-4563. PMC 3995271. PMID 24732162.
69. ^ "Electronic Cigarettes – An Overview" (PDF). German Cancer Research Center.
70. "Electronic cigarettes". Therapeutic Goods Administration.
71. ^ Bhatnagar, A.; Whitsel, L. P.; Ribisl, K. M.; Bullen, C.; Chaloupka, F.; Piano, M. R.; Robertson, R. M.; McAuley, T.; Goff, D.; Benowitz, N. (24 August 2014). "Electronic Cigarettes: A Policy Statement From the American Heart Association". Circulation. 130 (16): 1418–1436. doi:10.1161/CIR.0000000000000107.
72. ^ Mohney, Gillian, "First Child's Death From Liquid Nicotine Reported as 'Vaping' Gains Popularity", ABC News, December 12, 2014.
73. ^ "State Health Officer's Report on E-Cigarettes: A Community Health Threat" (PDF). California Department of Public Health, California Tobacco Control Program. January 2015.
74. ^ McNeill, A, SC (2015). "E - cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. p. 67–68. Retrieved 20 August 2015.{{cite web}}: CS1 maint: multiple names: authors list (link)
75. Arnold, Carrie (2014). "Vaping and Health: What Do We Know about E-Cigarettes?". Environmental Health Perspectives. 122 (9): A244–A249. doi:10.1289/ehp.122-A244. PMC 4154203. PMID 25181730.
76. ^ "Safety Watch: Electronic Cigarettes". U.S. Food and Drug Administration.
77. FDA (22 July 2009). "Summary of Results: Laboratory Analysis of Electronic Cigarettes Conducted By FDA". Retrieved 22 July 2009.
78. ^ FDA (4 May 2009). "FDA 2009 Study Data: Evaluation of e-cigarettes" (PDF). Food and Drug Administration (US) -center for drug evaluation and research. Retrieved 4 May 2009.
79. Palmer, Roxanne (8 September 2013). "E-Cigarettes As Effective As Nicotine Patches in Helping Smokers Quit: Study". International Business Times. Retrieved 15 December 2013.
80. "E-cigarettes to be regulated as medicines". National Health Service. 12 June 2013. Retrieved August 2013. {{cite web}}: Check date values in: |accessdate= (help)
81. ^ "WHO Right to Call for E-Cigarette Regulation". World Lung Federation.
82. "WMA Statement on Electronic Cigarettes and Other Electronic Nicotine Delivery Systems". World Medical Association.
83. ^ Oh, Anne Y.; Kacker, Ashutosh (December 2014). "Do electronic cigarettes impart a lower potential disease burden than conventional tobacco cigarettes?: Review on e-cigarette vapor versus tobacco smoke". The Laryngoscope. 124 (12): 2702–2706. doi:10.1002/lary.24750. PMID 25302452.
84. ^ Burstyn, I (9 January 2014). "Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks". BMC Public Health. 14: 18. doi:10.1186/1471-2458-14-18. PMC 3937158. PMID 24406205.{{cite journal}}: CS1 maint: unflagged free DOI (link)
85. ^ Schraufnagel, Dean E.; Blasi, Francesco; Drummond, M. Bradley; Lam, David C. L.; Latif, Ehsan; Rosen, Mark J.; Sansores, Raul; Van Zyl-Smit, Richard (2014). "Electronic Cigarettes. A Position Statement of the Forum of International Respiratory Societies". American Journal of Respiratory and Critical Care Medicine. 190 (6): 611–618. doi:10.1164/rccm.201407-1198PP. ISSN 1073-449X. PMID 25006874.
86. ^ Born, H.; Persky, M.; Kraus, D. H.; Peng, R.; Amin, M. R.; Branski, R. C. (2015). "Electronic Cigarettes: A Primer for Clinicians". Otolaryngology -- Head and Neck Surgery. doi:10.1177/0194599815585752. ISSN 0194-5998. PMID 26002957.
87. ^ Collaco, Joseph M. (2015). "Electronic Use and Exposure in the Pediatric Population". JAMA Pediatrics. 169 (2): 177–182. doi:10.1001/jamapediatrics.2014.2898. PMID 25546699.
88. ^ Orr, M. S. (2014). "Electronic cigarettes in the USA: a summary of available toxicology data and suggestions for the future". Tobacco Control. 23 (Supplement 2): ii18–ii22. doi:10.1136/tobaccocontrol-2013-051474. ISSN 0964-4563. PMID 24732158.
89. Detailed reference list is located on a separate image page.
90. Schroeder, M. J.; Hoffman, A. C. (2014). "Electronic cigarettes and nicotine clinical pharmacology". Tobacco Control. 23 (Supplement 2): ii30–ii35. doi:10.1136/tobaccocontrol-2013-051469. ISSN 0964-4563. PMID 24732160.
91. ^ Callahan-Lyon, P. (2014). "Electronic cigarettes: human health effects". Tobacco Control. 23 (Supplement 2): ii36–ii40. doi:10.1136/tobaccocontrol-2013-051470. ISSN 0964-4563. PMID 24732161.
92. ^ "E-cigarettes--prevention, pulmonary health, and addiction". Dtsch Arztebl Int. 111 (20): 349–55. 2014. doi:10.3238/arztebl.2014.0349. PMC 4047602. PMID 24882626. {{cite journal}}: Unknown parameter |authors= ignored (help)
93. ^ "Cancer Research UK Briefing: Electronic Cigarettes" (PDF). Cancer Research UK. May 2014.
94. "Electronic Cigarettes: Vulnerability of Youth". Pediatr Allergy Immunol Pulmonol. 28 (1): 2–6. 2015. doi:10.1089/ped.2015.0490. PMID 25830075. {{cite journal}}: Unknown parameter |authors= ignored (help)
95. Morris, Pamela B.; Ference, Brian A.; Jahangir, Eiman; Feldman, Dmitriy N.; Ryan, John J.; Bahrami, Hossein; El-Chami, Mikhael F.; Bhakta, Shyam; Winchester, David E.; Al-Mallah, Mouaz H.; Sanchez Shields, Monica; Deedwania, Prakash; Mehta, Laxmi S.; Phan, Binh An P.; Benowitz, Neal L. (2015). "Cardiovascular Effects of Exposure to Cigarette Smoke and Electronic Cigarettes". Journal of the American College of Cardiology. 66 (12): 1378–1391. doi:10.1016/j.jacc.2015.07.037. ISSN 0735-1097. PMID 26383726.
96. Weaver, Michael; Breland, Alison; Spindle, Tory; Eissenberg, Thomas (2014). "Electronic Cigarettes". Journal of Addiction Medicine. 8 (4): 234–240. doi:10.1097/ADM.0000000000000043. ISSN 1932-0620. PMID 25089953.
97. Centers for Disease Control and Prevention, (CDC) (6 September 2013). "Notes from the field: electronic cigarette use among middle and high school students – United States, 2011–2012". MMWR. Morbidity and mortality weekly report. 62 (35): 729–30. PMID 24005229.
98. Britton, John; Bogdanovica, Ilze (15 May 2014), Electronic cigarettes – A report commissioned by Public Health England (PDF), Public Health England
99. "Electronic cigarettes (e-cigarettes) or electronic nicotine delivery systems". World Health Organization. 3 June 2014.
100. "Position Statement on Electronic Cigarettes [ECs] or Electronic Nicotine Delivery Systems [ENDS]" (PDF). The International Union against Tuberculosis and Lung Disease. October 2013.
101. Alawsi, F.; Nour, R.; Prabhu, S. (2015). "Are e-cigarettes a gateway to smoking or a pathway to quitting?". BDJ. 219 (3): 111–115. doi:10.1038/sj.bdj.2015.591. ISSN 0007-0610. PMID 26271862.
102. ^ "White Paper: Electronic Cigarettes in the Indoor Environment" (PDF). American Industrial Hygiene Association. October 19, 2014.
103. ^ Offermann, Francis (June 2014). "The Hazards of E-Cigarettes" (PDF). ASHRAE Journal. 56 (6).
104. "American Lung Association Statement on E-Cigarettes". American Lung Association. 25 August 2014.
105. "E-cigarettes not proven quitting aid, says BMA". British Medical Association. 30 January 2013.
106. ""Smoking revolution": a content analysis of electronic cigarette retail websites". Am J Prev Med. 46 (4): 395–403. 2014. doi:10.1016/j.amepre.2013.12.010. PMID 24650842. {{cite journal}}: Unknown parameter |authors= ignored (help)
107. McNeill, A, SC (2015). "E - cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. p. 65. Retrieved 20 August 2015.{{cite web}}: CS1 maint: multiple names: authors list (link)
108. ^ Kleinstreuer, Clement; Feng, Yu (2013). "Lung Deposition Analyses of Inhaled Toxic Aerosols in Conventional and Less Harmful Cigarette Smoke: A Review". International Journal of Environmental Research and Public Health. 10 (9): 4454–4485. doi:10.3390/ijerph10094454. ISSN 1660-4601. PMID 24065038.{{cite journal}}: CS1 maint: unflagged free DOI (link)
109. "People who want to quit smoking should consult their GP". Faculty of Public Health.
110. "e-Cigarettes: a safe way to quit?". NPS MedicineWise.
111. Bam, T. S.; Bellew, W.; Berezhnova, I.; Jackson-Morris, A.; Jones, A.; Latif, E.; Molinari, M. A.; Quan, G.; Singh, R. J.; Wisotzky, M. (1 January 2014). "Position statement on electronic cigarettes or electronic nicotine delivery systems ". The International Journal of Tuberculosis and Lung Disease. 18 (1): 5–7. doi:10.5588/ijtld.13.0815. PMID 24365545.
112. ^ Suter, Melissa A.; Mastrobattista, Joan; Sachs, Maike; Aagaard, Kjersti (2015). "Is There Evidence for Potential Harm of Electronic Cigarette Use in Pregnancy?". Birth Defects Research Part A: Clinical and Molecular Teratology. 103 (3): 186–195. doi:10.1002/bdra.23333. ISSN 1542-0752. PMID 25366492.
113. "Electronic Nicotine Delivery Systems (ENDS), including E-cigarettes". New Zealand Ministry of Health.
114. ^ "Electronic cigarette use among smokers slows as perceptions of harm increase". ASH. 22 May 2015. Retrieved 6 August 2015.
115. McNeill, A, SC (2015). "E - cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. p. 79. Retrieved 20 August 2015.{{cite web}}: CS1 maint: multiple names: authors list (link)
116. McNeill, A, SC (2015). "E - cigarettes: an evidence update A report commissioned by Public Health England" (PDF). www.gov.uk. UK: Public Health England. pp. 6, 11, 78–80. Retrieved 20 August 2015.{{cite web}}: CS1 maint: multiple names: authors list (link)

External links

• Media related to Electronic cigarettes at Wikimedia Commons

• Electronic cigarettes