A study of more than 100 video games finds 42 percent feature characters smoking cigarettes, e-cigarettes, cigars and other products, or make references to those products. Experts tell CNN they are concerned young people who play the games may be influenced to start smoking.

The study by researchers at the University of California San Francisco included 118 games released between 1994 and 2015 that were rated by the Entertainment Software Ratings Board, which makes age recommendations for video games.

The findings were published in the journal Tobacco Control.

Previous studies have found that teens ages 12 to 17 who see the greatest amount of smoking in movies are about twice as likely to begin smoking, compared with their peers with the least exposure to smoking in movies. Much less is known about the effect of tobacco references in video games, the article notes.

Robin Koval, Chief Executive Officer and President of the tobacco-control advocacy organization Truth Initiative, told CNN that video games could be even more influential than movies. “We know video games are much more immersive (than movies) and frequently played by young people … those who play games spend even more time playing them than (time spent) on social media,” Koval said.

Dr. Brian A. Primack of the University of Pittsburgh, who has researched the effect of smoking in movies on teens, noted, “The influence (of video games) might even be stronger (than movies), both because of large exposures from repeated play and because of the highly personal, active nature of video game play.”