There is a general view that the risks associated with e-cigarette use, in terms of smoking-related diseases, are far less than that of combustible tobacco. This is due to the far lower levels of toxicants found in the e-cigarette aerosol, compared with cigarette smoke. Whether the risks are indeed lower cannot be demonstrated conclusively without long-term epidemiological studies.
The UK Royal College of Physicians considers medicinal nicotine to be a very safe drug. However certain groups of people such as pregnant women, those suffering from unstable heart disease, severe hypertension, diabetes or those with an allergy or sensitivity to nicotine would be best advised not to use nicotine-containing products. Additionally, it is well known that nicotine is addictive.
Nicotine has not been identified as a substance that causes cancer. For example, the International Agency for Research into Cancer has not identified nicotine as a carcinogen.
National Institute for Health and Clinical Excellence Public Health Draft Guidance
Nicotine at high doses has acute toxic effects and accidental exposure, especially through the skin or swallowing, can cause dizziness, nausea and vomiting and can be fatal if a particularly high dose is delivered quickly. A 30ml bottle of e-liquid may contain up to 5% nicotine or 1500mg. Most e-cigarette cartridges contain between 0.25-1ml e-liquid or 0-50mg nicotine. The lethal human oral dose is estimated to be about 50-60mg for an adult non-smoker and about 10mg for a child.
Nicotine is easily absorbed through the skin so care is required when handling e-liquids and the hands should be washed after handling.
Although glycerol and propylene glycol are widely used in the pharmaceutical, cosmetic and food industries and designated as ‘Generally Recognized as Safe’ (GRAS; for oral or dermal application) by the US Food and Drug Administration, the consequences of long-term exposure via inhalation are unknown and need to be investigated.
Other concerns with e-cigarettes include:
According to a 2012 study of e-cigarette use in the UK, based on a nationally representative sample of more than 12000 adults, only 0.1% of those who have never smoked report using e-cigarettes.
The only way to avoid the risks of smoking is to quit completely. However, as the June 2013 National Institute for Health and Clinical Excellence Public Health Draft Guidance “Tobacco: harm-reduction approaches to smoking” notes: ”there are other ways of reducing the harm from smoking, even though this may involve continued use of nicotine”. While the guidance does not support or recommend the use of unlicensed (i.e. nonmedicinally regulated) e-cigarettes, it does recommend a tobacco harm reduction approach that acknowledges adult users may continue to use nicotine for extended periods of time. As the report states: “using these products can make it easier for people to cut down before stopping, reduce their smoking or abstain.”
In some clinical studies using e-cigarettes, subjects have reported adverse events including irritation (throat and mouth), cough, dizziness, headache and nausea although these tended to become less severe with time.
One study in the USA has identified 47 adverse events related to e-cigarettes (eight classified as serious) reported between 2008 and 2012. These include hospitalization for illnesses such as pneumonia, congestive heart failure, disorientation, seizure, hypotension, second-degree burns to the face (from the exploded product), chest pain, rapid heartbeat and loss of vision requiring surgery. Less serious complaints include headache, chest pain, cough, vomiting, dizziness, confusion, sore throat, shortness of breath abdominal pain, pleurisy, blurry vision and sleepiness. The author states that some of these adverse events may be related to pre-existing conditions and not necessarily to the use of e-cigarettes.