Are electronic cigarettes a public health problem or a public health tool? They're both, and the government must treat them that way.

The latest news on e-cigarettes, electronic sticks that vaporize concentrated, nicotine-laced liquid, is that teen use of the devices is up — way up. The percentage of middle- and high-school-age minors using e-cigarettes tripled between 2013 and 2014, according to the National Youth Tobacco Survey, from 4.5 percent to 13.4 percent. That equates to 2.5 million kids vaping at least once in the month before they were surveyed.

Unsurprisingly, this astounding spike in teen use has some public health advocates very worried. Though e-cigarettes don't deliver conventional cigarettes' uniquely toxic cocktail of tar and other nasty chemicals, they certainly deliver nicotine, which affects teenage brain development, Centers for Disease Control and Prevention (CDC) Director Thomas Frieden warns. They also contain flavoring chemicals that might present some health risk.

Another major worry is how e-cigarettes will interact with conventional tobacco use. They could hook kids who go on to smoke them in conjunction with traditional cigarettes and other sorts of tobacco products. Or kids could graduate to smoking deadly conventional cigarettes exclusively.

But there's an upside visible in the numbers, too. Overall teen tobacco use is flat, and kids are smoking a lot fewer conventional cigarettes: Combustible cigarette use dropped 3.5 percentage points in a single year. That's great news. These figures suggest that some teenagers are starting up electronic cigarettes instead of lighting up old-school ones.

The Food and Drug Administration and many states are moving to regulate e-cigarettes. Top on the list must be figuring out how harmful various types of e-cigarettes are. From there, regulators should ensure that any risks that vaping liquid chemicals pose are minimized. Firm restrictions on sales to minors are also needed.

Ideally, the FDA would then draw a fine regulatory line. Cracking down on candy-style flavors transparently aimed toward teenagers makes sense. But regulators must also avoid rendering the product unattractive to smokers who want to reduce the risks of their habit but are wary of an electronic aftertaste. The FDA needs to restrict marketing to teenagers without sending inaccurate messages about e-cigarettes' risks. And the agency needs to find a way to encourage those who would never quit smoking to transition fully from combustible tobacco products without discouraging them from conquering their addiction, or never getting hooked to begin with.

FROM AN EDITORIAL IN THE WASHINGTON POST