E-Cigarettes

Background of Electronic Nicotine Delivery Systems

Invented in 2003 by Chinese pharmacist Hon Lik, electronic nicotine delivery systems (ENDS), also referred to as electronic cigarettes (e-cigarettes or ECIGS), constituted a 10 billion US dollar global market in 2015. Most e-cigarette sales occur online, consisting of extensive advertisement and multiple platforms for social communities surrounding e-cigarettes, which further facilitates the putative expansion of e-cigarette use by both adult and adolescent cliental. The market for e-cigarettes has rapidly grown with rates of expansion such as 132.5% over a 1 year span ending in 2013.

Typically, e-cigarettes are comprised of a cartridge for the e-cigarette liquid (e-liquid), a heating element, and a battery. The e-liquid is a solution of humectants (either propylene glycol and/or glycerol), distilled water, nicotine, flavoring, and other optional additives.

The mechanism by which the e-cigarette can allow for e-liquid inhalation involves the process of rapid heating and then cooling of the solution, producing an aerosol mist. A battery-powered electric current runs through a coiled resistance system within an atomizer where the e-liquid is stored, which saturates and, consequentially, heats the e-liquid. The liquid then vaporizes into an aerosol mist, a mixture of liquid droplets and gas, which is then inhaled or “vaped” by the user through a mouthpiece. The activation of this process can be initiated by either an air sensor upon inhaling, mimicking a cigarette, or manually initiated by pressing a button.

There is immense variation in terms of e-cigarette manufacturing and their use–there are roughly 460 brands and 8000 distinct e-liquid flavors, such as the popular menthol flavor as well as those resembling flavors of fruits, sweets and beverages. E-liquid solutions not only differ in flavoring, but also can vary in terms of nicotine concentrations, pH levels and additional additives. Nicotine concentration ranges from 0 to 24 mg/mL and to a maximum of 36 mg/mL; however, the typical concentration of nicotine-containing e-cigarettes has been averaged around 18 mg/mL ; this is notably much higher, in comparison with a domestic cigarette of which contains ∼6–13 mg of nicotine (an average of 12 mg), depending on the brand and manufacturer. Despite this, however, the actual nicotine concentration delivered to one's bloodstream after inhalation is overall lower in comparison with levels following tobacco cigarette use.

Other points of variation exist due to the different e-cigarette models, the style of inhalation used as well as device manipulation by the user. E-cigarettes are being used for purposes that extend beyond nicotine consumption, including flavor manipulation, smoke tricks, and the inhalation of other substances. For example, substances, such as cannabis, vitamins, herbs and vodka, have been reportedly inhaled using e-cigarettes. A trend in e-cigarette use is for cannabis consumption, a popular substance choice to vape, due to the decreased amounts of smoke and odor. One risk that exists with consumption of cannabis via e-cigarettes is that tetrahydrocannabinol (THC) levels can exceed combustion-produced methods by 4- to 30-fold. Furthermore, e-cigarettes are also being used for “dripping,” which involves dripping a few drops of a choice substance directly onto the coil atomizer of the e-cigarette and inhaling what is immediately and directly vaporized from the high temperature, leading to better product delivery or experienced “throat hit.”

Overall, e-cigarettes generate a smokeless aerosol absent of carbon monoxide. The aerosol's further constituents, however, depend directly on the e-liquid ingredients, the electrical processes (e.g., resistance and voltage), the temperature of heating, and the type of coil or wire used as a conductor.

E-cigarettes have potential risk factors associated with their use. Nonetheless, there have also been suggested benefits, especially among individuals with tobacco use disorder and the possibility of the device being used for smoking cessation and reduction. Such benefits include that nicotine in an aerosol may be self-administered with fewer tobacco toxicants compared to tobacco smoke resulting in reduced health risk. The most prominent barrier for e-cigarette regulation and consensus is the current limited experimental evidence as well as the predicted advanced and rapid evolution of the devices and their use, further contributing to variation. There are also three different e-cigarette generations that consist of various device characteristics and manipulation abilities, which facilitates even more variation in the e-cigarette discussion. Not only do these factors contribute to the difficulty in regulation, but they also contribute to the difficulty in generalizing the risks and benefits, the specific ingredients, and details of drug delivery.

Reasons for Use of E-Cigarettes

In general, e-cigarettes are perceived to be a healthier, less harmful/toxic, and less addictive alternative to tobacco cigarettes. Moreover, e-cigarettes are generally perceived to be a useful aid in smoking cessation or reduction. One of the most common reasons for e-cigarette use is to address tobacco cravings and withdrawal in attempts of smoking reduction or cessation, as use of e-cigarettes has been perceived as or even more efficacious in comparison with nicotine replacement therapies (NRTs). Interestingly, adolescents do not use e-cigarettes primarily for smoking cessation, unlike the general adult population. Flavoring is a major appeal for youth, as well as for adults, supporting the migration away from tobacco flavoring preferences.

Other reasons for use of e-cigarettes include evading smoke-free policies and second-hand disturbances that are normally associated with the smoke from tobacco cigarettes. Further reasons include curiosity, accessibility, social influence, manageable cost, and the preferred taste or smell. Some individuals also report using e-cigarettes because of resemblances to the sensations surrounding oral inhalation and experience of nicotine delivery in comparison with smoking tobacco cigarettes. Another major appeal for all e-cigarette users is the adjustability and reuse of the device. For example, replaceable coils and voltage variance can affect current flow and heating of the coil, promoting different throat hits or aerosol amounts, respectively.

Among individuals who discontinue using e-cigarettes, initial use is more likely to be for experimentation rather than for a specific goal, such as smoking cessation. Other reasons for no longer using e-cigarettes involve the negative health perceptions, manual characteristics of the device, as well as the taste, vapor, look or feel, and cost of the device.