Consumer Reports

Chances are good that you’ve seen people “smoking” e-cigarettes: inhaling from cigarette-shaped devices, then puffing out clouds of odorless fog. E-cigarettes, also known as e-cigs or electronic nicotine delivery systems, have been on the market for about a decade and are surging in popularity. But there’s widespread disagreement about their safety or any benefits they may have.

Proponents say that e-cigs, a $2.8 billion market in the United States, are potentially less harmful than conventional cigarettes and can help smokers quit. Critics say that their safety hasn’t been proved and that it’s too soon to know what the long-term effects of “vaping” (inhaling the vapor) may be. Consumer Reports spoke with medical experts and reviewed more than 50 scientific studies to find out what’s known.

How they work

A typical battery-operated e-cigarette contains a cartridge of e-cig liquid, or juice, which usually contains nicotine and the chemical propylene glycol. The juices come in an array of flavors including cola and watermelon, which some say are meant to attract younger users. When used, the battery powers an atomizer that vaporizes the liquid in the cartridge for the user to inhale.

Aside from those basics, e-cigarettes vary widely in terms of ingredients, construction and factors such as battery voltage. The Food and Drug Administration, which regulates regular cigarettes, has proposed regulating e-cigarettes more tightly, but some politicians and many in the industry oppose the FDA’s plan.

The nicotine issue

Juice from e-cigarettes has different amounts of the addictive stimulant nicotine, from zero to about 72 milligrams per milliliter of liquid. (A traditional cigarette has 10 to 15 milligrams.) “Nicotine has short-term negative health effects, like increasing your heart rate and blood pressure, so it can aggravate heart conditions,” says Marvin M. Lipman, Consumer Reports’ chief medical adviser. “It also interferes with fetal development, making it unsafe in pregnancy regardless of its source.”

Larger doses of nicotine can be more harmful, especially to children, who may be attracted by the sweet flavors and brightly colored packages. And in 2014, poison-control centers responded to 3,783 e-cigarette and liquid nicotine exposure cases. More than half of those involved children younger than 6 who might have ingested or inhaled liquid nicotine or gotten it on their skin or in their eyes. In 2015, those centers received 3,067 nicotine-exposure reports across all age groups.