Seven recent deaths in America have been linked to the use of electronic cigarettes. The federal government and some states have made moves to ban the use of the products - other countries, such as India, are following.
But some experts believe that vaping has a useful role to play in helping people to give up smoking.
In this week's programme David Aaronovitch asks why have e-cigarettes become so popular, and what are the risks of using them?
CONTRIBUTORS
Tom Novotny, Professor of Epidemiology and Biostatistics, San Diego State University
Hannah Kuchler, US Pharma and Biotech Correspondent, The Financial Times
Linda Bauld, Professor of Health Policy, the University of Edinburgh
Lion Shahab, Associate Professor in Health Psychology, University College London.
Producer Neil Koenig Editor Jasper Corbett