Johnston says legalization of medical marijuana may affect teens' views on pot use
"Record Numbers of Teens Think Marijuana Is Harmless" - ScientificAmerican.com. 3/19/2013.
Although use of marijuana among teens carries risks, a shrinking number of teens in the Monitoring the Future study view regular pot use as harmful, according to Lloyd Johnston. He cites the legalization of marijuana in many states as a probable influence: “This shift in perceived risk may very well have resulted from the widespread endorsement of medical marijuana use.”