Soaring use of e-cigarettes among young people “is now a major public health concern,” according to a report published Thursday from the United States Surgeon General. It is the first comprehensive look on the subject from the nation’s highest public-health authority, and it finds that e-cigarettes are now the most commonly used tobacco product among youths, surpassing tobacco cigarettes.

E-cigarettes, which turn nicotine into inhalable vapor, can harm developing brains of teenagers who use them, and also can create harmful aerosol for people around the user, the report said, citing studies in animals.

“Adolescent brains are particularly sensitive to nicotine’s effects,” and can experience “a constellation of nicotine-induced neural and behavioral alterations,” the report said. It urged stronger action to prevent young people from getting access to e-cigarettes.

Some researchers have said that e-cigarette use among youth could act as a gateway to traditional smoking, but the report says the relationship is not yet fully established. Cigarette smoking among youth has fallen sharply in recent years but use of nicotine products over all remains essentially flat among young people.