While public health messages include e-cigarettes for smoking cessation, the evidence base for how much they help smokers to stop is still limited, especially compared to licensed medicines, PHE acknowledged in March 2018.16

In terms of safety, nicotine delivery from e-cigarettes has improved as the technology develops.

“This could mean that their addiction potential has increased, but this may also make them more attractive to smokers as a replacement for smoking. It is not yet clear how addictive e-cigarettes are, or could be, relative to tobacco cigarettes,” PHE says.

Nor is the long-term impact of nicotine from e-cigarettes on lung tissue known, and it may be different from its systemic impact. However, PHE estimates that the e-cigarette cancer potency is under 0.5% of the risk of smoking.

Safety concerns have been raised including poisonings from e-cigarette liquid, both accidental (such as in young children) and deliberate including in self-harm and suicide attempts. Equipment has also been known to explode or cause a fire.

Recent studies have also found:17,18

·      reactions occurring between e-cigarette liquids, flavourings and solvents, can create compounds with toxicological properties.

·      e-cigarette liquid vapour condensing on lung tissue is cytotoxic, and stimulates an inflammatory response while inhibiting phagocytic activity in alveoli, but the health implications have yet to be determined.