Despite their advantages, e-cigarettes are not completely risk-free. Find out if experts think these reported concerns are valid.

Long-term safety CONCERN: E-cigarette vapour might contain traces of cancer-causing chemicals like formaldehyde or toxic metals like nickel. Repeatedly inhaling these over many years could cause health problems.

IS IT VALID? This is a possibility, and there is not yet enough long-term research on e-cigarettes to know for sure. But the evidence currently available suggests very low levels of toxins in e-cigarette users. Many scientists, such as those working with Public Health England, therefore think the risks are likely to be low – and certainly much lower than with tobacco.

Nicotine addiction CONCERN: The nicotine in e-cigarette vapour is still highly addictive. Some studies suggest nicotine might be linked to anxiety and blood vessel problems.

IS IT VALID? There is a lack of definitive evidence. But according to a Public Health England report, scientists believe the levels of nicotine in e-cigarettes are unlikely to pose any significant health risk.

Gateway to smoking CONCERN: The availability of relatively safe e-cigarettes could normalise the activity of smoking and make it socially acceptable again. Non-smokers could be enticed to start vaping and eventually move to smoking.