One-fifth of American adults who have never smoked cigarettes have tried non-cigarette tobacco products, according to a study presented at an American Heart Association meeting.

Young adult non-smokers ages 18 to 39 are most likely to have tried non-cigarette tobacco products, HealthDay reports.

“In general, cigarette use has decreased,” said study author Dr. Javier Valero-Elizondo. “But we are now seeing that use of e-cigarettes, cigars, cigarillos, hookahs and other products are on the rise. This study was about shining a light on a potential problem we didn’t previously know the size of.”

The researchers analyzed data from 77,623 adults who had never smoked. They found 22% said they had used at least one non-cigarette tobacco product. This suggests that 32.7 million American adults have tried these products.