As more states adopt laws allowing medical marijuana, fewer teens see occasional marijuana use as harmful, the largest national survey of youth drug use has found.
Nearly 80 percent of high school seniors dont consider occasional marijuana use harmful the highest rate since 1983 and record numbers smoke it regularly, according to the annual survey of eighth-, 10th- and 12th-graders made public Wednesday.
More than one in five high school seniors said they smoked marijuana in the month before the survey, and more than a third smoked marijuana during the previous year, according to Monitoring the Futures survey of 45,449 students from 395 public and private schools. The survey has measured drug, alcohol and cigarette use since 1975.
A growing number of state laws that allow marijuana for medical use contributes to teen perceptions that marijuana is not a harmful drug, said Dr. Nora Volkow, director of the National Institutes of Healths National Institute on Drug Abuse, which sponsors the study.
When teens perceive drugs as safe, drug use generally increases, Volkow said. Among eighth-graders, more than 50 percent dont see the harm of occasional marijuana use, while 42 percent consider occasional use of marijuana harmful the lowest rate since the survey began tracking risk perception for this age group in 1991.
A study published this year in the Proceedings of the National Academy of Sciences found that heavy marijuana use beginning as a teen and stretching into adulthood causes an average drop of 8 points in IQ scores.
Thats a very robust indication that (smoking marijuana) may have long-term effects, Volkow said.
The 2012 survey found 6.5 percent of high school seniors smoke marijuana daily, up from 5.1 percent five years ago. Almost 23 percent smoke marijuana regularly. Among 10th-graders, 3.5 percent smoke marijuana daily, the survey found. Marijuana use escalates dramatically after eighth grade, when 1.1 percent of the students report daily use.
But even most eighth-graders dont see the harm of occasional use, the survey found.
I think thats the bad news in the survey the significant increases in the regular use of marijuana, Volkow said. Its not just the occasional use. You have a very high rate of daily use. Thats really a huge number.
Use of other illegal drugs continued to show a steady decline. Past-year use of all illegal drugs except for marijuana is a record low for all three grades, the survey found.
These long-term declines in youth drug use in America are proof that positive social change is possible, White House Office of National Drug Control Policy Director Gil Kerlikowske said.
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