Teen marijuana use rising after years of decline

More American high school seniors are smoking marijuana daily now than at any time since the early 1980s, and they're actually smoking more pot than cigarettes, according to a survey released Tuesday.

About 6 percent of high school seniors reported smoking marijuana daily in the new survey, which involved more than 46,000 teens in the eighth, 10th and 12th grades. That's up from 2 percent in 1991 and the same percentage that smoked daily in 1981.

The survey results show an end to almost a decade of declining rates of pot use. They came as a sharp disappointment to anti-drug advocates and addiction researchers, who blamed the shift primarily on the growing national discussions on medicinal marijuana and legalizing pot - conversations that have received heavy emphasis in California.

Medical pot talk blamed

With so much talk about the potential health benefits of pot, teenagers are increasingly complacent about the risks of marijuana, public health experts say.

"When you talk about the potential health benefits of marijuana, it's the equivalent of saying heroin is a great pain medication, so you shouldn't be wary of it," said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which funded the study. "A drug may have compounds that have therapeutic benefits, but that in no way decreases its toxic effects."

The "Monitoring the Future" survey, done by researchers at the University of Michigan at Ann Arbor, has reported on drug use among teenagers every year since 1975. The survey looks at alcohol consumption, cigarette smoking and use of illicit drugs such as marijuana, prescription medications, cocaine and ecstasy.

Eight percent of eighth-graders and 21.4 percent of high school seniors reported having smoked marijuana at least once in the previous 30 days, when the survey was taken earlier this year. That is a small but statistically significant increase for both age groups over the previous year, when 6.5 percent of eighth-graders and 20.6 percent of seniors smoked pot in the previous month.

About 19 percent of high school seniors reported having smoked a cigarette in the same 30-day period.

Almost 44 percent of high school seniors and more than 17 percent of eighth-grade students reported having used marijuana at least once in their life, also small increases over the previous year.

Teenagers in the survey were less worried about the possible health risks of smoking marijuana. Among high school seniors, 47 percent said they think of marijuana as harmful, compared with 52 percent in 2009.

Tops in addiction programs

That's a dangerous perception, said addiction specialists, who noted that in California, more teenagers are admitted to inpatient addiction programs for marijuana use than for any other drug, including alcohol.

"We had a vote this year about decriminalizing marijuana further. Is it a big surprise that perceived risk is down and daily use is up?" said Dr. John Mendelson, a senior scientist with the Addiction and Pharmacology Research Laboratory at California Pacific Medical Center. "This is the dark side of the medical marijuana movement. The main risk for kids is addiction. And it's a substantial risk."

Aside from the possibility of becoming addicted to marijuana, public health experts said that even occasional pot smoking can affect memory and, in turn, classroom performance. Many teenagers who wouldn't ever drive drunk might not recognize the risk associated with driving while under the influence of marijuana, Volkow said.

But with such a strong public debate taking place on the medical use of marijuana, and a recent push to legalize it, teenagers are getting mixed messages, she said.

The survey results aren't available for specific states or cities in the United States, but San Francisco public health experts said that, at least anecdotally, the city has long had higher-than-average rates of marijuana use among teenagers.

"Generally, San Francisco has been a high marijuana-using city for at least 40 years," said Jim Stillwell, deputy director of community behavioral health for the city's Public Health Department. "But San Francisco schoolkids don't do as much as the national average in most other drug categories."

Mixed news on other drugs

There was a mix of good news and bad news in the survey when it came to teenage use of other types of drugs. Nonmedical use of prescription drugs remains popular, and there was a small increase in ecstasy use among all age groups, after several years of decline.

Cocaine use did not change from 2009 to this year, but it's been falling steadily since the early 1990s. Alcohol use was down for all teens. About 41 percent of high school seniors reported having consumed alcohol at least once in the past 30 days, and 27 percent said they got drunk.

E-mail Erin Allday at eallday@sfchronicle.com.

This article appeared on page A - 1 of the San Francisco Chronicle