WASHINGTON, Dec. 18 (Xinhua) -- The percentage of high- schoolers who see great risk from being regular marijuana users has dropped dramatically in the past 10 years, according to an annual survey released Wednesday by the U.S. National Institute on Drug Use (NIDA).
The survey, which measures drug use and attitudes among the country's eighth-, 10th-, and 12th-graders, reported continued high rates of marijuana use in all three grades and predicted higher use in future years.
It found that only 39.5 percent of 12th graders view regular marijuana use as harmful, down from last year's rate of 44.1 percent, and considerably lower than rates from the last two decades.
The rates of marijuana use have also shown significant changes in the past two decades, with 6.5 percent of seniors smoking marijuana daily compared to 6 percent in 2003 and 2.4 percent in 1993, it said.
"This is not just an issue of increased daily use," NIDA Director Nora Volkow said in a statement. "It is important to remember that over the past two decades, levels of THC -- the main psychoactive ingredient in marijuana -- have gone up a great deal, from 3.75 percent in 1995 to an average of 15 percent in today's marijuana cigarettes. Daily use today can have stronger effects on a developing teen brain than it did 10 or 20 years ago."
Nearly 23 percent of seniors said they smoked marijuana in the month prior to the survey, and just over 36 percent said they smoked it during the past year.
For 10th graders, 4 percent said they use marijuana daily, with 18 percent reporting past month use and 29.8 percent reporting use in the previous year.
More than 12 percent of eighth graders said they used marijuana in the past year.
"We should be extremely concerned that 12 percent of 13- to 14- year-olds are using marijuana," Volkow added. "The children whose experimentation leads to regular use are setting themselves up for declines in IQ and diminished ability for success in life."