WASHINGTON — The Obama administration on Wednesday sounded the alarm over rising marijuana use among the nation’s youth, saying that softening attitudes about the perceived risk of the drug are responsible for the increase.

Sixty percent of 12th-graders do not view regular marijuana use as harmful, and more than 12 percent of eighth-graders said they had used the drug in the past year, according to a survey released by the National Institute on Drug Abuse.

“Making matters worse, more teens are now smoking marijuana than smoke cigarettes,” said Gil Kerlikowske, President Barack Obama’s drug czar. “Well, this isn’t a recipe for raising a healthy generation of young people who are prepared to meet America’s challenges.”

He criticized the legalization of marijuana in Washington state and Colorado, calling the plans “a very large social experiment.” And he delivered a clear shot aimed at pro-legalization advocates who argue that marijuana is safer than alcohol, saying: “For some to say that it is less dangerous than other substances is a ridiculous statement.”

The survey found that 23 percent of high school seniors used marijuana in the past month, compared with 16 percent who smoked cigarettes.

Among 12th-graders, 6.5 percent said they smoked pot every day, and more than 36 percent said they had smoked it in the past year. Among 10th-graders, 4 percent said they used marijuana daily, with 18 percent reporting past month use, and 29.8 percent said they had used it in the previous year.

“These are very high numbers, considering that these are kids at school,” said Nora Volkow, director of the National Institute on Drug Abuse, which conducts the yearly study as part of a project with the University of Michigan.

Volkow, who joined Kerlikowske in a conference call with reporters to release the study, said this year’s survey carried some bright spots: Alcohol and tobacco use declined, and fewer students said they were using synthetic marijuana.

But the survey cited the misuse of prescription stimulants as another “cause for concern.” The percentage of 12th-graders who said they used amphetamines for non-medical reasons in the past year rose from 6.8 percent in 2008 to 8.7 percent in 2013, and officials said that many of them said they were using them not for fun but before exams hoping to boost their performance.

Kerlikowske, a former Seattle police chief who now serves as the director of the Office of National Drug Control Policy for the White House, called the marijuana results both “a serious setback” and a disappointment.

He said schools have done a poor job on dealing with drug education, eliminating it or making it an inconsistent part of their health curriculum.

And he predicted that Washington state and Colorado, the two states that last year voted to legalize the recreational use of marijuana, will face “a very difficult time” as they move forward with their plans to sell the drug in retail stores beginning in 2014.

“It’s an important issue and … clearly these two states are engaging in a very large social experiment,” Kerlikowske said.

He said kids who live in states with medical marijuana laws already are finding it easier to obtain the drug, proving that state-regulated systems are having trouble confining the marijuana to adults. Kerlikowske said the survey found that 34 percent of high school seniors who live in states with medical marijuana laws say that one of the ways they’ve obtained the drug is from others who have gotten prescriptions to buy the drug.

Volkow said marijuana use among school-age children could hinder their brain development and put them at increased risk of addiction in later years.

“We should be extremely concerned that 12 percent of 13- to 14-year-olds are using marijuana,” Volkow said. “The children whose experimentation leads to regular use are setting themselves up for declines in IQ and diminished ability for success in life.”

The Marijuana Policy Project, which has criticized Kerlikowske in the past for his anti-marijuana stance and his office’s drug studies, said federal officials should investigate whether regulating marijuana like alcohol and cigarettes could lead to lower rates of use.

“The results suggest that regulating alcohol and cigarettes is successfully reducing teen use, whereas marijuana prohibition has been unsuccessful,” said Mason Tvert, the group’s spokesman in Denver. He said those who sell marijuana in the underground market “are not asking for ID,” and that regulating the drug would lower availability for teens.

Ethan Nadelmann, executive director of the pro-legalization Drug Policy Alliance, said that while he’s concerned by the increase in daily marijuana use among teens, “that’s no reason to persist with a prohibitionist marijuana policy that has resulted in over 700,000 people getting arrested each year.

The report is the latest example of how the Obama administration has sent mixed signals on marijuana use this year.

In August, the Justice Department said it would not block Colorado and Washington state from opening their retail pot stores next year, so long as the states do a good job of policing themselves.

Kerlikowske, who has consistently opposed legalization, said his office now intends to work with the Justice Department to study rates of drugged driving in the two states and to see whether they’re successful in keeping pot away from minors, as they’ve promised to do.

Obama this summer nominated Kerlikowske to take the job of U.S. customs commissioner, but he remains in his current post as the Senate has yet to vote on his confirmation.

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