In recent years, e-cigarettes have been introduced to the global market. This device was invented by Ruyan Group (Holdings) Limited, China in 2003, and the company patented e-cigarettes in Canada in 2004 [17
]. E-cigarettes look like real cigarettes, but do not burn and combust tobacco leaves; thus, the e-cigarette manufacturers and distributors insist that it is safer than other tobacco products. The device consists of a plastic tube, an electronic heating element, a liquid nicotine cartridge, a lithium battery, and atomization chamber with a membrane to suspend ingredients [18
]. It also has an LED-generated red light to simulate the burning end of a cigarette. Because of the lack of combustion involved in an e-cigarette, the device does not deliver tar or chemical elements that are present in regular cigarettes that are known to cause and increase the risk of developing cardiovascular and pulmonary diseases. Instead, there is a replaceable cartridge containing nicotine (with the ability of the user to adjust the nicotine concentration), chemical additives, and flavours (e.g. chocolate, coffee, mint, fruits). As the user exhales, some visible vapour is released, but no tobacco smoke. With these features, the e-cigarette industry insists that the device is safe, can be used in non-smoking areas, and is free from second-hand smoke concerns.
Are e-cigarettes truly safe? Can they be used as a smoking cessation aid as the industry advertises? There is a lack of scientific evidence offering clear answers to these questions. There are a few short-term studies that have investigated e-cigarettes [19
], but the evidence is not sufficient to conclusively end the controversial debates on the safety of e-cigarettes. Despite the lack of scientific evidence to confirm the e-cigarette industry's claims of safety, e-cigarettes are being sold and distributed throughout South Korea and worldwide. The World Health Organisation (WHO) and the US Food and Drug Administration (US FDA) have warned against the widespread use of e-cigarettes as a nicotine replacement product. Both bodies have recognised that e-cigarettes may be less harmful than tobacco smoking, given the lack of tar in e-cigarettes, but they emphasise that e-cigarettes are almost certainly more dangerous than medicinal nicotine replacement products [19
The WHO defines that the e-cigarette as an electronic nicotine delivery system (ENDS). The Organisation not only recommends that ENDS be treated differently from traditional tobacco products, but also recommends that until conclusive evidence shows that e-cigarettes are safe, they should not be marketed as a nicotine replacement product, and that marketing activities of the e-cigarette manufacturers and distributors must be strictly controlled [19
The US FDA has attempted to treat e-cigarettes as a drug-delivery device under the Food, Drug, and Cosmetic Act since January 2010. As a result, e-cigarette manufacturers were required to submit an application for evaluation and approval of their device before they could be marketed to the public. This decision was based on US FDA's research showing that e-cigarettes contained carcinogens, including nitrosamines, toxic chemicals, such as diethylene glycol, and tobacco-specific components suspected of being harmful to humans, such as anabasine, myosmine, and beta-nicotyrine [20
]. However, the US Court of Appeals ruled that the FDA lacked the authority to regulate e-cigarettes as drugs or devices on 6th December 2010. In response, the FDA announced that e-cigarettes would be regulated as a tobacco product [21
]. Meanwhile, given the lack of evidence regarding e-cigarettes' safety or efficacy as a smoking cessation aid, Australia, Canada, Singapore, and Brazil have banned the sale of e-cigarettes [19
There is some research to support that e-cigarettes are effective in reducing the desire to smoke; however, this research was funded by Ruyan Group (Holdings) Limited. In this study, 40 participants were randomised to use e-cigarettes containing 16 mg nicotine, placebo e-cigarettes, or medicinal nicotine inhalators for four days. The results indicated that there was no difference in reducing desire to smoke between a 16 mg e-cigarette and an inhalator, which can be interpreted to mean that e-cigarettes probably work similarly to medicinal nicotine replacement inhalators. In addition, the 16 mg e-cigarettes were found to be more pleasant to use than a nicotine inhalator [22
]. Not surprisingly, these findings support the e-cigarette industry in advertising their device as a smoking cessation aid.
Although a few studies are available, given the absence of evaluation of e-cigarettes for longer-term safety, potential effects of long-term use and efficacy as a smoking cessation aid, uncertainty on e-cigarettes still remain. As such, more careful and comprehensive control polices and measures on e-cigarettes are urgently needed to prevent unexpected public health impacts.