The federal government's move to regulate e-cigarettes is a leap into the unknown.

Most everyone agrees a ban on selling them to kids would be a step forward. But health and public policy experts can't say for certain whether the electronic devices are a good thing or a bad thing overall, whether they help smokers kick the habit or are a gateway to ordinary paper-and-tobacco cigarettes.

The proposed rules, issued Thursday by the Food and Drug Administration, tread fairly lightly. They would ban sales to anyone under 18, add warning labels and require FDA approval for new products.

Some public health experts say a measured approach is the right one. They think that the devices, which heat a nicotine solution to produce an odorless vapor without the smoke and tar of burning tobacco, can help smokers quit.

"This could be the single biggest opportunity that's come along in a century to make the cigarette obsolete," said David Abrams, executive director of the Schroeder Institute for Tobacco Research and Policy Studies at the American Legacy Foundation.

Still, some wonder whether e-cigarettes keep smokers addicted or hook new users and encourage them to move on to tobacco. And some warn that the FDA regulations could have unintended consequences.

Read more at the Associated Press