The American Heart Association’s first policy statement on electronic cigarettes backs them as a last resort to help smokers quit. The American Cancer Society has no formal policy but quietly took a similar stance in May.

Both groups express great concern about these popular nicotine-vapor products and urge more regulation, especially to keep them away from youth. They also stress that proven smoking cessation methods should always be tried first.

But if those fail, “it is reasonable to have a conversation” about e-cigarettes, said the Heart Association’s president, Dr. Elliott Antman. The Cancer Society said e-cigarettes “may be a reasonable option” for people who could not quit after trying counseling and approved methods, such as nicotine patches.

Neither group recommends e-cigarettes for smoking cessation, and makers of the devices do not market them that way.

E-cigarettes are battery-powered devices that vaporize nicotine. They’ve been sold in the U.S. since 2007 and now have millions of users worldwide and nearly $2 billion in annual sales. They contain less toxic substances than traditional cigarettes do, but little is known about their health effects.

Whether they help or hurt anti-smoking efforts is hotly debated. Some say they encourage smoking by letting people maintain their habit in places where cigarettes are banned. Others say they are a less risky way to satisfy a nicotine craving for people who want to quit, similar to how methadone is used to curb heroin abuse.

This concept, called harm reduction, “is probably the most important and the most contentious issue that the tobacco community is dealing with right now,” said Tom Glynn, who recently retired as the Cancer Society’s top scientist on the e-cigarette issue.