Teenagers are very familiar with the risks of smoking cigarettes but thanks to misinformation campaigns by advocates regarding marijuana, and campaigns against the poorly-named "e-cigarettes" by pharmaceutical companies selling competing smoking cessation tools like gums and patches, they are less likely to buy into advertised claims.

"Kids were really good at describing the harmful things that happen with cigarette smoking, but when we asked about other products, there was a lot of confusion," said the study's lead author, Maria Roditis, PhD, a postdoctoral scholar in adolescent health at the Stanford University School of Medicine..

"We're good at delivering messaging that cigarettes are harmful, but we need to do a better job with other products that teens may smoke," added Bonnie Halpern-Felsher, PhD, professor of pediatrics in adolescent medicine and the study's senior author. "We don't want the message kids get to be 'cigarettes are bad, so everything else might be OK.'"

Halpern-Felsher and Roditis compared teens' knowledge of cigarettes, e-cigarettes and marijuana because they heard from teachers, parents and youth that anti-smoking efforts needed to address more than just conventional cigarettes. The need is borne out by other research: A recent study from the Centers for Disease Control shows that middle- and high-school students' use of e-cigarettes tripled from 2013 to 2014, eclipsing conventional cigarettes as the most common tobacco product in this age group.

Halpern-Felsher and Roditis studied 24 adolescents who attended high school in a Northern California school district known to have high rates of substance use. The students participated in small-group discussions about their perceptions of the risks and benefits of conventional cigarettes, e-cigarettes and marijuana. They also discussed how they learned about these products. The researchers analyzed the themes that emerged in the discussions.

Students perceived little or no benefit, as well as several detrimental effects, of smoking conventional cigarettes, such as yellowed teeth, bad breath and long-term disease risk. They also said their social norms often discouraged smoking conventional cigarettes. For instance, even smoking marijuana rolled in paper was considered weird because it looks like a cigarette.

Perceptions versus reality

However, students saw getting high as a benefit to smoking marijuana, and perceived it as safer and less addictive than tobacco. They were unsure whether marijuana posed health risks, and also described being under peer pressure to smoke marijuana.

With respect to e-cigarettes, students perceived some benefits, including thinking e-cigarettes looked good, and were unsure of the risks.

Students' sources of information about the three products were varied. The media, families and teachers all warned against the use of conventional cigarettes. Students also got messages from these sources discouraging use of marijuana, but said it was difficult to refuse the drug because its use was so prevalent among their peers. Students received few, mostly informal, messages about e-cigarettes: They said they saw family members using them to try to quit conventional cigarettes, and also saw peers using them.

The findings could help shape future messages about marijuana and e-cigarettes, the study's authors said. For instance, students need to hear about the addictive potential of both products; about the risks of smoking any form of plant matter, which is similar between conventional cigarettes and marijuana; and about the presence of nicotine in e-cigarettes. In addition, flavorants in e-cigarettes may raise the risk of obstructive lung disease.

"Students hear a lot of talk about conventional cigarettes, some about marijuana and very little about e-cigarettes," Halpern-Felsher said. "That gap needs to be filled in classrooms and by health-care providers, parents and the media. We don't want to leave one product behind and leave teens with the impression that, 'Maybe this is the product I can use.'"

Published in the Journal of Adolescent Health.