Are Electronic Cigarettes Safe?

Electronic cigarettes, also known as e-cigarettes and electronic nicotine delivery devices, are becoming a popular alternative to cigarette smoking. Sold at mall kiosks, on the Internet, and at some convenience stores, electronic cigarettes allow the user to consume nicotine by simulating cigarette smoking without producing second-hand smoke. An electronic cigarette, which resembles a metallic cigarette, contains flavored, liquefied nicotine encased in a plastic cartridge that is placed into a battery-operated device. When the smoker actuates the button, a vaporized puff of nicotine is released to be inhaled. Despite the seemingly growing popularity of electronic cigarettes, several countries, including Canada, Australia, and Brazil, have banned them.^[1]
The US Food and Drug Administration (FDA) has issued warnings about the lack of scientific and clinical trial data to support the safety of electronic cigarettes.^[2] Yet, many reasons are offered for the use of these devices. According to an Internet survey of 3587 electronic cigarette users^[3]:

• 84% of those surveyed perceived e-cigarettes to be less toxic than tobacco smoke;
• 77% used them as a smoking cessation tool or to prevent relapse;
• 79% used them to deal with cravings; and
• 67% used them to deal with withdrawal symptoms.

In addition to the perception that e-cigarettes may be safer, it is plausible that some smokers may feel more comfortable using the device because they are able to "smoke" in public places where cigarette smoking is banned. This claim is somewhat legitimate because the e-cigarette emits vapor, not smoke. This is an area of current debate, in part because safety data are lacking and because the flavored liquid nicotine used in electronic cigarettes is not approved by the FDA. At present, the FDA intends to develop regulations for the manufacturing and sale of liquid nicotine and electronic cigarettes.
Little clinical trial data exist regarding the safety and efficacy of electronic cigarettes. Polosa and colleagues found a potential link between use of electronic cigarettes and reduction in number of cigarettes used per day.^[4] This 6-month pilot study evaluated 40 regular smokers not intending to quit who were given the opportunity to use e-cigarettes. A sustained 50% reduction in the number of cigarettes smoked was noted in about one third of patients at week 24. Over 22% of patients discontinued using cigarettes at week 24; however, most of them were still using e-cigarettes. Although this proof-of-concept study is intriguing, larger studies must be conducted to further delineate the role, if any, of e-cigarettes in long-term smoking cessation.
Of note, the FDA performed preliminary testing of certain samples of leading e-cigarette products, and public health concerns emerged^[5]:

• The tested products contained detectable levels of known carcinogens or toxic chemicals (eg, diethylene glycol, tobacco-specific nitrosamines, and tobacco-specific impurities);
• Quality control processes for the manufacture of these products were inconsistent; and
• Cartridges released variable amounts of nicotine.

The FDA is encouraging the public, both users of electronic cigarettes and healthcare professionals, to report any adverse effects or potential quality control problems associated with the use of electronic cigarettes.^[5]
At this time, little conclusive evidence supports the safety and efficacy of electronic cigarettes, either for recreational use or as a smoking cessation aid. However, it is likely that some researchers and manufacturers will embark on further clinical trials. Patients who are motivated to stop smoking should be encouraged to discuss smoking cessation therapies with their healthcare providers and be informed of the multiple FDA-approved options and behavioral modification therapies available for smoking cessation.
The author wishes to thank Krysten Rodgers for providing technical assistance