Electronic cigarette

First generation electronic cigarette resembling a tobacco cigarette

Second generation types of electronic cigarettes

An electronic cigarette (e-cig or e-cigarette), personal vaporizer (PV) or electronic nicotine delivery system (ENDS) is a battery-powered device which simulates tobacco smoking by producing a vapor that resembles smoke. It generally uses a heating element known as an atomizer, that vaporizes a liquid solution. Solutions usually contain a mixture of propylene glycol, glycerin, nicotine, and flavorings, while others release a flavored vapor without nicotine. The e-cigarette aerosol contains nicotine, ultrafine particles, other toxic chemicals, carcinogens, and metal nanoparticles. in amounts ranging from 10 to 100 times lower than traditional cigarettes. There is a poor relationship between labeled and existing nicotine content, as well as differing levels of other chemicals and toxicants in the e-liquid and aerosol. Various e-liquid flavors include tobacco, menthol, coffee, fruit, candy, and alcohol flavors, cola and Belgian waffle.

First generation electronic cigarettes were usually designed to simulate smoking implements, such as cigarettes or cigars, in their use and appearance. They produced less vapor than second generation personal vaporizers since they use smaller batteries. New generation electronic cigarettes have an increased nicotine-dispersal performance, housing higher capacity batteries, and come in various form factors, including metal tubes and boxes.

The benefits and risks of electronic cigarette use are uncertain. They carry a risk of nicotine addiction in those who do not already smoke, and possibly continue addiction in those who already smoke: their regulation is the subject of ongoing debate. There are concerns that these products should be adequately regulated, mainly to protect users, while avoiding unintended consequences caused by excessive or inappropriate regulation. Most people who use electronic cigarettes have a history of smoking cigarettes while some young people who have never smoked cigarettes have tried electronic cigarettes at least once. The frequency of use has increased with up to 10% of American high school students having ever used them as of 2012 and around 3.4% of American adults as of 2011. The majority of e-cigarette users continue to smoke traditional cigarettes.

A "smokeless non-tobacco cigarette" was patented in 1963 by Herbert A. Gilbert, which drew moistened air through a heating element. Hon Lik invented an e-cigarette using piezoelectric components in 2003. E-cigarette devices are predominately manufactured in China. The e-cigarette brands have been rapidly expanding using aggressive marketing campaigns similar to those used to popularize cigarettes in the 1950s and 1960s. Because of the relative novelty of the technology and the possible relationship to tobacco laws and medical drug policies, electronic cigarette legislation and public health investigations are currently pending in many countries. Current regulations vary widely, from regions with no regulations to others banning the devices entirely.

Health

Smoking cessation

The World Health Organization (WHO) has stated the efficacy of electronic cigarettes in aiding smoking cessation has not been demonstrated. The WHO recommend that "consumers should be strongly advised not to use" electronic cigarettes unless a reputable national regulatory body has found them safe and effective.

The concept of harm reduction has largely been controversial in the public health approach of tobacco control. A 2011 review states how electronic cigarettes may aid in smoking cessation and may likely be more effective than traditional pharmacotherapy, as the physical stimuli of holding and puffing on the electronic cigarette may better reduce short-term cravings. The review found no studies that directly measured the effectiveness of electronic cigarettes in smoking cessation, and examined two published studies that indirectly consider the issue by measuring the effect of the product on cravings and other short-term indicators. A 2014 review asserted how electronic cigarettes may be a reasonable substitute for cigarette smoking.

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 chewing tobacco for long term use instead of smoking.

The British Medical Association (BMA) reports there is a possibility for smoking cessation benefits, but has concerns that e-cigarettes are less regulated than nicotine replacement therapy (NRT), and that there is no peer reviewed evidence concerning their safety or efficacy. Recommendations point to a "strong regulatory framework" for e-cigarette distribution in order to ensure the safety, quality, and that marketing and sales are restricted to adults. The BMA 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.

Common reasons people use the e-cigarette is a desire to quit smoking cigarettes, cut down on their smoking habit or to circumvent smoke-free laws.

A report commissioned by Public Health England concluded that there is large potential for health benefits when switching from tobacco use to other nicotine delivery devices such as electronic cigarettes, but realizing the full potential requires regulation and monitoring to minimize possible risks.

A 2012 review found electronic systems appear to generally deliver less nicotine than smoking, raising the question of whether they can effectively substitute for tobacco smoking over a long-term period.

A 2013 randomized controlled trial found no difference in smoking cessation rates between e-cigarettes with nicotine, e-cigarettes without nicotine and traditional NRT patches. There are some non-controlled studies which have reported possible benefit.

Electronic cigarettes were not regularly associated with trying to quit tobacco among young people. Adults most often used electronic cigarettes as a replacement for tobacco, although not invariably to quit. The majority of e-cigarette users continue to smoke traditional cigarettes. Although the majority of youth using e-cigarettes are dual users, one third of young people who used an e-cigarette have never tried a traditional cigarette, indicating that some young people are initiating use of the addictive drug nicotine through e-cigarettes. Although the evidence is limited, research points to high levels of dual use of e-cigarettes with traditional cigarettes, no proven cessation assistance, and a rapid increase in youth initiation with e-cigarettes. Although some people have a desire to quit smoking by using e-cigarettes, other common explanations for the use of these products are to evade smoke-free laws and to cut back on traditional cigarettes, which may reinforce delaying or deterring to quit smoking.

Safety

The emerging phenomenon of electronic cigarettes has raised concerns among the health community, pharmaceutical industry, health regulators and state governments. Limited evidence suggests e-cigarettes are safer than real cigarettes, and possibly as safe as other nicotine replacement products. However, there is a serious concern with the purity of ingredients. E-cigarettes are more likely to result in reduced exposure to nicotine and potential risk of disease but there is insufficient evidence to support this assertion. The FDA stated that e-cigarettes have not been fully studied for their potential risks. Few studies have directly examined the health effects of exposure to e-cigarette aerosol, but some show the potentiality of e-cigarette aerosol exposure resulting in biological effects. Long-term biological effects are currently unknown since e-cigarettes haven't been in widespread use long enough for evaluation. Major injuries and illness have occurred from using e-cigarette such as explosions and fires. Not as serious adverse events included throat and mouth inflammation, cough, nausea, and vomiting. There is a poor relationship between labeled and existing nicotine content, as well as differing levels of other chemicals and toxicants in the e-liquid and aerosol. The e-cigarette aerosol contains nicotine, ultrafine particles, other toxic chemicals, and carcinogens. The levels of toxic and carcinogenic compounds in the aerosol were found to be 1 to 2 orders of magnitude smaller than in cigarette smoke but greater compared to a nicotine inhaler. E-cigarettes deliver nicotine by forming an aerosol of ultrafine particles, which are variable and chemically intricate, and the specific compounds accountable for toxicity and the comparative importance of particle size and particle composition are generally unknown. Nonsmokers when exposed to secondhand e-cigarette aerosol were found to have detectable levels of the nicotine metabolite cotinine in their blood. Although research is limited, it is transparent that e-cigarette emissions are not simply "harmless water vapor," as is commonly claimed. Heavy metals were found in e-cigarette liquids and aerosol. Tin was detected as both particles and tin whiskers in the liquid and Poly-fil, and e-cigarette liquid contaminated with tin was cytotoxic to human pulmonary fibroblasts. The aerosol was also found to contain other metals, such as nickel, 2 to 100 times greater than detected in Marlboro cigarette smoke. The nickel and chromium nanoparticles possibly originated from the heating element. These metal nanoparticles can deposit in the lung's alveolar sacs, which may lead to local respiratory toxicity, entering the bloodstream. The human toxicity thresholds of possible toxicants in e-cigarette vapor are unknown. Using e-cigarettes in a clean air environment may introduce harmful indoor air pollution and it may reinforce the idea of smoking as socially acceptable. E-cigarettes do not smolder the way traditional cigarettes do, so they do not emit smoke, but bystanders are at a potential risk to the exhaled e-cigarette aerosol. E-cigarette users are not likely to obtain any benefit of reduced rates of cardiovascular disease. 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." There are possible health hazards associated with tobacco-specific nitrosamines (TSNAs) and diethylene glycol (DEG).

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) states that there is enough evidence to say that switching to electronic cigarettes would likely be healthier than smoking. However, due to the lack of regulation of the contents of the numerous different brands of electronic cigarettes and the presence of nicotine, which is not a benign substance, the CDC has issued warnings.

A 2012 review raised concerns about the lack of regulatory oversight over the manufacturing process, marketing, and quality control. Also of concern were the purity of ingredients as well as the ease with which these devices can be modified.

The BMA has noted literature finding electronic cigarettes as safer than tobacco smoking, but also is concerned by the lack of high quality peer-reviewed studies about safety. They have noted that the amount of nicotine delivered can be highly variable between devices due to differences in how well the nicotine is vaporized. They have also raised concerns that the delivered dose may be inconsistent or misleading compared to the nicotine level stated on the liquid container, with identically labelled cartridges emitting "markedly different" levels of nicotine. Issues around proper labeling, child-proof packaging, and electrical safety have also been raised.

A preliminary analysis of e-cigarette cartridges by the US Food and Drug Administration (FDA) in 2009 identified that some contain tobacco-specific nitrosamines (TSNAs), known cancer-causing agents. The amounts of TSNAs present were on par with existing NRT products like nicotine gum and inhalers. The FDA's analysis also detected diethylene glycol, a poisonous and hygroscopic liquid, in a single cartridge manufactured by Smoking Everywhere and nicotine in one cartridge claimed to be nicotine-free. Diethylene glycol was found in a cartridge tested in 2009 by the FDA, but in 2011 researchers reviewed the data and noted that 15 other studies had failed to find any evidence of this chemical in e-cigarettes. Further concerns were raised over inconsistent amounts of nicotine delivered when drawing on the device. In some e-cigarettes, "Tobacco-specific impurities suspected of being harmful to humans – anabasine, myosmine, and β-nicotyrine – were detected in a majority of the samples tested." 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.

Addiction

A number of organizations including the Centers for Disease Control and Prevention, the International Union Against Tuberculosis and Lung Disease, the American Academy of Pediatrics and the Food and Drug Administration have concerns that e-cigarettes might increase addiction to and use of nicotine and tobacco products in children. The World Health Organization raises the concern of addiction for nonsmokers from their use. It is not clear whether vaping e-cigarettes will curtail or boost nicotine addiction.[1]

Construction

Disassembled cigarette-styled electronic cigarette.
A. LED light cover
B. battery (also houses circuitry)
C. atomizer (heating element)
D. cartridge (mouthpiece)

Battery connected to a USB charger

Most electronic cigarettes take an overall cylindrical shape although a wide array of shapes can be found: box, pipe styles etc. Many are made to look like tobacco cigarettes. Common components include a liquid delivery and container system, an atomizer, and a power source. Many electronic cigarettes are composed of streamlined replaceable parts, while disposable devices combine all components into a single part that is discarded when its liquid is depleted.

Atomizer

Along with the battery, the atomizer is the central component of every personal vaporizer. Although many kinds of atomizers are in use, they generally consist of a small heating element responsible for vaporizing liquid, as well as a wicking material that draws liquid in.

A small length of resistance wire is wrapped around the wicking material and then connected to the positive and negative poles of the device. When activated the resistance wire (or coil) quickly heats up thus turning the liquid into a vapor, which is then inhaled by the user.

The electrical resistance of the coil, the voltage output of the device, the airflow of the atomizer and the efficiency of the wick play important roles in the perceived quality of the vapor that is produced by an atomizer. They also greatly affect the quantity or volume of vapor that will be produced by the atomizer.

Atomizer resistances usually vary from 1.5Ω (ohms) to 3.0Ω from one atomizer to the next but can go as low as 0.1Ω in the most extreme cases of DIY coil building which produce large amounts of vapor but could present a fire hazard and other dangerous battery failures if the user is not knowledgeable enough about basic electrical principles and how they relate to battery safety.

Wicking materials vary greatly from one atomizer to another but silica fibers are the most commonly used in manufactured atomizers. "Rebuildable" or "do it yourself" atomizers can use silica, cotton, porous ceramic, hemp, bamboo yarn, oxidized stainless steel mesh and even wire rope cables as wicking materials.

A wide array of atomizers and e-liquid container combinations are available:

Cartomizers

Most of the devices that imitate the cigarette form factor use a "cartomizer" (a portmanteau of cartridge and atomizer) or "carto" as an e-liquid delivery system. The piece consists of a heating element surrounded by a liquid-soaked poly-foam that acts as an e-liquid holder. It is usually disposed of once the e-liquid acquires a burnt taste, which is usually due to an activation when the coil is dry or when the cartomizer gets consistently flooded (gurgling) because of sedimentation of the wick. Most cartomizers are refillable even if not advertised as such.

Cartomizers can be used on their own or in conjunction with a tank that allows more e-liquid capacity. In this case the portmanteau word of "cartotank" has been coined. When used in a tank, the cartomizer is inserted in a plastic, glass or metal tube and holes or slots have to be punched on the sides of the cartomizer to allow liquid to reach the coil.

Clearomizers

eGo style e-cigarette with a top-coil clearomizer. Silica fibers are hanging down freely inside of the tank, drawing e-liquid by capillary action to the coil that is located directly under the mouthpiece.

Clearomizers or "clearos", not unlike cartotanks, use a clear tank in which an atomizer is inserted. Unlike cartotanks, however, no poly-foam material can be found in them. There are a lot of different wicking systems employed inside of clearomizers to ensure good moistening of the wick without flooding the coil. Some rely on gravity to bring the e-liquid to the wick and coil assembly (bottom coil clearomizers for example) whereas others rely on capillary action and to some degree the user agitating the e-liquid while handling the clearomizer (top coil clearomizers).

Rebuildable Atomizers

A rebuildable atomizer or an RBA is an atomizer that allows the user to assemble or "build" the wick and coil themselves instead of replacing them by an off-the-shelf atomizer "head". They also allow the user to build atomizers at any desired electrical resistance. The materials needed to "rebuild" the atomizers are usually much cheaper than the usual prefabricated replaceable wick and coil assemblies destined to clearomizers.

These atomizers are divided into two main categories; rebuildable tank atomizers (RTA's) and rebuildable dripping atomizers (RDA's).

Rebuildable tank atomizers or RTA's are similar to clearomizers in that they use a tank or container to hold and bring liquid to the coil. They usually hold a lot more e-liquid than their RDA counterparts.

Rebuildable dripping atomizers or RDA's on the other hand lack the container section and hold very little liquid compared to RTA's but are usually a lot smaller. They usually consist only of an atomizer "building deck" which can accept one or more coils and a "top cap" to cover the coils where a mouth piece can be attached. The user needs to manually keep the atomizer wet by dripping liquid on the bare wick and coil assembly, hence their name.

Power

Most portable devices contain a rechargeable battery, which tends to be the largest component of an electronic cigarette. The battery may contain an electronic airflow sensor whereby activation is triggered simply by drawing breath through the device, while other models employ a power button that must be held during operation. An LED to indicate activation may also be employed. Some manufacturers also offer a cigarette pack-shaped portable charging case (PCC), which contains a larger battery capable of charging e-cigarettes. Devices aimed at more experienced users may sport additional features, such as variable power output and support of a wide range of internal batteries and atomizer configurations and tend to stray away from the cigarette form factor. Some cheaper recent devices use an electret microphone with a custom IC to detect airflow and indicate battery status on the included blue LED.

Variable power and voltage devices

PV with variable and regulated power offering battery protection

Variable voltage or power personal vaporizers are devices that contain a built in electronic chip that allows the user to adjust the power that goes through the heating element. They usually incorporate a LED screen to display various information. Variable PV's eliminate the need of having to replace an atomizer with another one of lower or higher electrical resistance to change the intensity of the vapor. They also feature voltage regulation and some battery protection.

Some of these devices offer additional features through their menu system such as: atomizer resistance checker, remaining battery voltage, puff counter, activation cut-off etc.

Mechanical personal vaporizers

Mechanical PV with a rebuildable atomizer

Mechanical PVs or mechanical "mods", often called "mechs" are devices without electronic components and battery protection (apart from vent holes drilled in some mechanical devices) or electric regulation. Because there is neither protection nor regulation, they will work either way the battery is inserted. They are activated by spring loaded or opposing magnetic mechanical switches, hence their name. They rely entirely on the natural voltage output of a battery.

They are commonly used with "low resistance" (1.0Ω ~ 0.2Ω) rebuildable atomizers. Seeing that most e-cigarettes containing electronic battery protection will interpret sub ohm resistance coils as a short circuit, thus prohibiting the device from being activated, mechanical mods are among the only devices that will accept such atomizer resistances although more recent (2013) electronic devices offers this possibility as well

Since mechanical PVs are unregulated and unprotected, they require special attention on the user's part that other regulated and protected PVs do not need. Making sure that the battery does not over-discharge and that the atomizer will not require more amperage than what the battery can safely allow are the user's responsibilities.

Liquid

Liquid for producing vapor in electronic cigarettes, commonly known as e-juice or e-liquid, is a solution of propylene glycol (PG), vegetable glycerin (VG), and/or polyethylene glycol 400 (PEG400) mixed with concentrated flavors; and optionally, a variable concentration of nicotine. PG can cause eye and respiratory inflammation.

The solution is often sold in a bottle or in pre-filled disposable cartridges. They are manufactured with various tobacco, fruit, and other flavors, as well as variable nicotine concentrations (including nicotine-free versions). The standard notation "mg/ml" is often used in labeling for denoting nicotine concentration, and is sometimes shortened to a simple "mg".

Various e-liquid flavors include tobacco, menthol, coffee, fruit, candy, and alcohol flavors, as well as odd flavors like cola and Belgian waffle. A disproportionate use of flavored traditional tobacco products are used by youth and initiators, and flavored cigarettes except menthol have been banned in the U.S.

Usage statistics

Electronic cigarette sales increased from 50,000 in 2008 to 3.5 million in 2012. As of 2011, in the United States, one in five adults who smoke have tried electronic cigarettes. In a UK survey conducted in 2013 of more than 12,000 adults, 11% of regular smokers in the sample identified themselves as using electronic cigarettes and 24% stated that they had used them in the past. Amongst those who had never smoked in the same sample, 1% said they had tried them and no evidence of continued use. In 2014 the number of people who had every smoked who reported using electronic cigarettes was 52%.

Among grade 6 to 12 students in the United States, those who have ever used the product increased from 3.3% in 2011 to 6.8% in 2012. Those currently using electronic cigarettes increased from 0.6% to 1.1%. Over the same period the percentage of grade 6 to 12 students who regularly smoke tobacco cigarettes fell from 7.5% to 6.7%. 10% of students who have used e-cigarettes at least once have never smoked. A 2013 UK survey by Action on Smoking and Health found that among non-smokers under 18, 1% reported having tried e-cigarettes "once or twice," and no evidence of continued use. ASH concluded that among children who have heard of e-cigarettes, sustained use is rare and confined to children who smoke or have smoked.

A February 2014 survey by the French Monitoring Centre for Drugs and Drug Addiction of 2052 individuals estimated that between 7.7 and 9.2 million individuals have experimented with using electronic cigarettes, with between 1.1 and 1.9 million using on a daily basis. 67% of tobacco smokers in the survey used electronic cigarettes to reduce or quit tobacco smoking. 9% of those who experimented with electronic cigarettes had never smoked tobacco. Of the 1.2% that had recently stopped tobacco smoking at the time of the survey, 84% (or 1% of the population surveyed) credited electronic cigarettes for stopping tobacco use.

History

The earliest electronic cigarette can be traced to Herbert A. Gilbert, who in 1963 patented a device described as "a smokeless non-tobacco cigarette" that involved "replacing burning tobacco and paper with heated, moist, flavored air." This device heated the nicotine solution and produced steam. In 1967, Gilbert was approached by several companies interested in manufacturing it, but it was never commercialized and disappeared from the public record after 1967.

Hon Lik, a Chinese pharmacist, is credited with the invention of the electronic cigarette. In 2003, he came up with the idea of using a piezoelectric ultrasound-emitting element to vaporise a pressurized jet of liquid containing nicotine diluted in a propylene glycol solution. This design produces a smoke-like vapour that can be inhaled and provides a vehicle for nicotine delivery into the bloodstream via the lungs. He also proposed using propylene glycol to dilute nicotine and placing it in a disposable plastic cartridge which serves as a liquid reservoir and mouthpiece.

Electronic cigarettes using a different design were first introduced to the Chinese domestic market in May 2004 as an aid for smoking cessation and replacement. The company that Hon Lik worked for, Golden Dragon Holdings, changed its name to Ruyan (如烟, literally "Resembling smoking"), and started exporting its products in 2005–2006 before receiving its first international patent in 2007. E-cigarette devices are predominately manufactured in China. The e-cigarette brands have been rapidly expanding using aggressive marketing campaigns similar to those used to popularize cigarettes in the 1950s and 1960s. Long banned comparative advertising for cigarettes and other tobacco products, e-cigarette advertising on television and radio in a number of countries may be indirectly advocating traditional cigarette smoking.

The electronic cigarette continued to evolve from the first generation three-part device. In 2006 the "cartomizer" was invented by British entrepreneurs Umer and Tariq Sheikh of XL Distributors. This is a mechanism which integrates the heating coil into the liquid chamber. The new device was launched in the UK in 2007 in their Gamucci brand and is now widely adopted by the majority of 'cigalike' brands. The grant of the UK patent for the "cartomizer" was made to XL Distributors in February 2013 and published by the UK Intellectual Property Office.

The international tobacco companies, recognising the development of a potential new market sector that could render traditional tobacco products obsolete, are increasingly involved in the production and marketing of their own brands of e-cigarettes and in acquiring existing e-cigarette companies. Blu, a prominent US e-cigarette producer, was acquired by Lorillard Inc. in 2012. British American Tobacco launched Vype in 2013, while Imperial Tobacco's Fontem Ventures acquired the intellectual property owned by Hon Lik through Dragonite for $US 75 million in 2013 and launched Puritane in partnership with Boots UK. On 3 February 2014, Altria Group, Inc. acquired popular electronic cigarette brand Green Smoke for $110 million. The deal is expected to be finalized during the second quarter of 2014. Altria also markets its own e-cigarette, the MarkTen, while Reynolds American has entered the sector with its Vuse product.

Society and culture

As the electronic cigarette industry grows, a subculture has emerged which calls itself "the vaping community". Members of this emerging subculture often view electronic cigarettes as a safer alternative to smoking and some even view it as a hobby. They tend to use highly customized devices that do not resemble what are known, by some, as "cig-a-likes," or electronic cigarettes that resemble real cigarettes. Well known celebrities have also embraced this new found culture by taking their electronic cigarettes to public events such as movie award shows and press conferences.

Legal status

Main article: Legal status of Electronic Cigarettes

Because of the relative novelty of the technology and the possible relationship to tobacco laws and medical drug policies, electronic cigarette legislation and public health investigations are currently pending in many countries. Current regulations vary widely, from regions with no regulations to others banning the devices entirely.

Related nicotine inhalation technologies

There are other technologies currently under development that seek to deliver nicotine for oral inhalation in an effort to mimic both the ritualistic and behavioural aspects of traditional cigarettes.

• British American Tobacco, through their subsidiary Nicoventures Limited, licensed a nicotine delivery system based on existing asthma inhaler technology. The technology is being developed by UK-based healthcare company Kind Consumer Limited.
• Philip Morris International bought the rights to a nicotine pyruvate technology developed by Jed Rose at Duke University. The technology is based on the chemical reaction between nicotine acid and a base, which produces an inhalable nicotine pyruvate vapour.

External links

• Media related to Electronic cigarettes at Wikimedia Commons
• FDA information page on electronic cigarettes