Teenagers and young adults are the primary users of e-cigarettes, with 10 percent of U.S. high school-aged adolescents and 11 percent of U.S. young adults (18-24 years) vaping. A new study in the July 2024 Pediatrics, “Modification of Electronic Nicotine Delivery Systems among Adolescents and Young Adults,” found that not only are teenagers and young adults vaping, but they’re modifying e-cigarettes in unexpected and potentially dangerous ways.