E-cigarettes contain "a few cancer causing substances" and there is not enough evidence that they help smokers to quit, according to a World Health Organisation (WHO) manager who is calling for their regulation.
Dr Armando Peruga, Programme Manager of WHO's Tobacco Free Initiative said nicotine is "a key component of electronic cigarettes and affects the brain development of adolescents and foetuses of pregnant women."
He added: "Electronic cigarettes contain nicotine and other chemicals and usually a few cancer causing substances although a much lower level than a conventional cigarette, it doesn't mean that there not without risk."
More top news
Nearly 38,000 runners will hope to complete Sunday's London Marathon making it the biggest event in its 35-year history.
Rain across central Britain with longer, intense downpours with thunder in places this evening. A lucky few will stay sunny and dry.
Planning on going to the London Marathon tomorrow? Read our handy guide first!