An electronic cigarette, personal vaporizer or electronic nicotine delivery system 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, vegetable glycerin, nicotine, and flavorings,
The concept of harm reduction has largely been controversial in the public health approach of tobacco control. 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. The review also states that even individuals that did not intend to quit smoking before being introduced to e-cigarettes may subsequently do so.
The British Medical Association reports there is a possibility for smoking cessation benefits, but has concerns that e-cigarettes are less regulated than nicotine replacement therapy, 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.
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. 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. and to cut back on traditional cigarettes, which may reinforce delaying or deterring to quit smoking.
Safety
The risks of electronic cigarette use are uncertain. This is due to there being little data regarding their health effects However, some evidence suggests e-cigarettes may be safer than smoking tobacco products, and possibly as safe as other nicotine replacement products but there is insufficient data to draw conclusions.
A preliminary analysis of e-cigarette cartridges by the US Food and Drug Administration in 2009 identified that some contain tobacco-specific nitrosamines, 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 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. While propylene glycol and other chemicals commonly used as solvents