Vaping is generally considered less dangerous than smoking, because burning tobacco or marijuana generates chemicals that are harmful to lungs. But there is little research on e-cigarettes' long-term effects, including whether they help smokers quit.
The rise in teenagers using e-cigarettes has alarmed health officials who worry kids will get addicted to nicotine, a stimulant, and be more likely to try cigarettes.
"Shifts in social acceptability and access to cannabis could occur as several states consider legalized cannabis sales for adults," the researchers wrote in a letter published in JAMA Pediatrics on Monday.
The letter comes on the heels of a recent statement from Food and Drug Administration Commissioner Scott Gottlieb, who last week declared youth vaping an "epidemic." The FDA gave the five largest e-cigarette makers 60 days to produce plans to stop underage use of their products.
"In the largest coordinated enforcement effort in the FDA's history, the agency issued more than 1,300 warning letters and civil money penalty complaints (fines) to retailers who illegally sold JUUL and other e-cigarette products to minors during a nationwide, undercover blitz of brick-and-mortar and online stores this summer," the agency news release stated.
While critics have often argued vaping is a partial solution to America's cigarette smoking crisis, Gottlieb said there are "clear signs that youth use of electronic cigarettes has reached an epidemic proportion."
“Teenagers are becoming regular users, and the proportion of regular users is increasing,” he added. “We’re going to have to take action.”
It's unclear whether marijuana vaping is increasing among teens or holding steady. The devices have grown into a multi-billion industry, but they are relatively new.
The Associated Press contributed to this story.