New medical research in the Journal of the American Medical Association has found that 11% of high school seniors admit to using a prevalent and easily accessible synthetic marijuana, known as delta-8 THC. That number translates to “at least one or two students in every average-sized high school class,” according to Nora Volkow, director of the National Institute on Drug Abuse. A lack of federal regulation means there’s no age restriction on the over-the-counter product, found readily in gas stations, online and in convenience stores in many states — leaving experts worried.