E-cigarette age restriction push by US regulators
The US Food and Drug Administration (FDA) wants minimum age restrictions and health warnings on e-cigarettes.
The agency is pushing for alterations to US law due to uncertainties over the health effects of e-cigarettes and the rapid take-up of the devices.
The FDA also wants to limit vending machine sales of e-cigarettes.
"The tobacco product marketplace is evolving at a dizzying pace with many unanswered questions about the health effects of novel products," it said.
The new rules would also extend current US law to cigars, pipe tobacco, nicotine gels, hookah pipe tobacco, and "dissolvables not already under the FDA's authority".
No timetable has been given for the proposed changes to the law.
Use of e-cigarettes has expanded from thousands of people in 2006 to several million worldwide, with estimated sales of almost $2bn in 2013.
E-cigarettes are plastic or metal tubes that use an electrical coil to heat a liquid nicotine solution, creating a vapour that users inhale.
The FDA is conducting research into the health effects of e-cigarettes, and who uses them, according to Mitch Zeller, the director of the FDA's Center for Tobacco Products.
"Right now for something like e-cigarettes, there are far more questions than answers," he said.
Under the proposed new rules, e-cigarette makers would be required to register their products with the agency and to disclose ingredients.
They also would not be allowed to claim their products are safer than other tobacco products.