A man uses an E-cigarette, an electronic substitute in the form of a rod, slightly longer than a normal cigarette, in this file illustration picture taken in Paris, March 5, 2013. The growing ... more 
A man uses an E-cigarette, an electronic substitute in the form of a rod, slightly longer than a normal cigarette, in this file illustration picture taken in Paris, March 5, 2013. The growing popularity of e-cigarettes has not escaped the notice of the industry's U.S. critics, who have stepped up calls for new regulations, including bans on their use in public places, even though the scientific evidence about exposure to their vapors remains inconclusive. REUTERS/Christian Hartmann/Files (FRANCE - Tags: HEALTH SOCIETY SCIENCE TECHNOLOGY BUSINESS) less 
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Reuters | Photo By CHRISTIAN HARTMANN / REUTERS
Wed, Dec 11, 2013 1:58 PM EST