A study in the April 2018 issue of Pediatrics, "Self-Identified Tobacco Use and Harm Perceptions Among U.S. Youth," asked 20,675 students in 6th through 12th grades whether they consider themselves tobacco product users.
The results showed that approximately three out of five teens who use e-cigarettes and cigars, and four out of five of those who use roll-your-own tobacco or pipes did not consider themselves tobacco product users. More so, the majority of teens who used only e-cigarettes or hookahs thought that these products were not harmful, even though many considered "all tobacco products" and any other specific tobacco product they did not use (e.g., cigarettes, smokeless tobacco) as being harmful.
These results suggest an underreporting of actual tobacco use by teens. Researchers offer that the underreporting could be that the teens really do not see themselves as tobacco users despite using tobacco products, or do not see the harm in certain tobacco products, such as e-cigarettes and hookahs.
The authors conclude that health care providers may get a better understanding of adolescent tobacco use by asking about a variety of tobacco products (e-cigarettes, hookahs, roll-your-own) and how they are used (i.e. occasional/social smoking), rather than just asking about tobacco use overall.
Additional Information from HealthyChildren.org: