An anonymous reader quotes a report from Philly.com: Teens who vape e-cigarettes with higher nicotine levels are more likely to start smoking conventional cigarettes soon after, new research shows. E-cigarettes are sold with nicotine levels ranging from zero to more than 25 milligrams of nicotine per milliliter (mg/mL). In this study, a high-nicotine device was defined as having levels at or above 18 mg/mL. Leventhal's team tracked outcomes for 181 grade-10 students from high schools in the Los Angeles area. All of the teens said they had used e-cigarettes within the past month, and they provided data on nicotine levels in the devices they used. Six months later, those who used higher nicotine levels in their e-cigarettes were more likely to report use of both e-cigarettes and regular cigarettes within the past month. These teens also reported vaping and/or smoking more intensely. While 43 percent of the students who'd used high-nicotine e-cigarettes said they were "frequent smokers" of traditional cigarettes six months later, that was true for only 10 percent of those who'd vaped using lower-nicotine devices, Leventhal's group found. And teens who vaped using high-nicotine e-cigarettes smoked an average of 14 times as many "regular" cigarettes per day six months later compared to those who'd tried nicotine-free versions of the devices, the findings showed. The study was published in JAMA Pediatrics.