DETROIT - Smoking marijuana is becoming more popular among U.S. teens even as they have cut down on smoking cigarettes, binge drinking, and using methamphetamine, a federal survey released yesterday found.

More teens also are getting high on prescription pain pills and attention-deficit drugs, according to eighth, 10th and 12th graders surveyed by the University of Michigan for the National Institute on Drug Abuse.

The increase of teens smoking pot is partly because the national debate over medical use of marijuana can make the drugs seem safer to teenagers, researchers said. In addition to marijuana, fewer teens also view prescription drugs and ecstasy as dangerous, which often means more could use them in the future, White House drug czar Gil Kerlikowske said.

"These latest data confirm that we must redouble our efforts to implement a comprehensive, evidence-based approach to preventing and treating drug use," Kerlikowske, the director of the Office of National Drug Control Policy, said in remarks prepared for his speech yesterday at the National Press Club in Washington.

Marijuana use, while well off peak levels of the late 1990s, has edged up. According to the study of 47,097 students, among 12th graders, 20.6 percent said they used it within the last month, compared with 19.4 percent in 2008 and 18.3 percent in 2006.

In the last year, the share of eighth graders who smoked pot was 11.8 percent, compared with 10.9 percent in 2008. Tenth graders' use was 26.7 percent this year and 23.9 percent in 2008. The percentage of 12th graders was 32.8 percent, compared with 32.4 percent in 2008.

"The upward trending of the past two or three years stands in stark contrast to the steady decline that preceded it for nearly a decade," said Lloyd Johnston, who has directed the annual survey since it started in 1975.

Marijuana's growing popularity is tied to how risky teens think it is, officials said.

"When the perception of the danger goes down, in the following years you see an increase in use," National Institute on Drug Abuse Director Nora Volkow said.

Volkow said teens falsely reasoned it's less dangerous to get high on prescription drugs "because they're endorsed by the medical community." But she said prescription narcotics such as OxyContin and Vicodin were highly addictive and could act as gateways to heroin.