THURSDAY, Aug. 19 (HealthDay News) -- Drugs and gangs are common problems at public schools in the United States, a new teen survey shows.

Among public school students aged 12 to 17, 27 percent (5.7 million) report that their schools are both "gang- and drug-infected." Drug-infected means that drugs are used, kept or sold on school grounds.

The 15th annual teen survey by the National Center on Addiction and Substance Abuse at Columbia University also found that 46 percent of teens in public schools say there are gangs in their schools and 47 percent of teens say that drugs are used, kept or sold on school grounds.

Compared with teens who go to drug-free and gang-free schools, those at schools infected with both drugs and gangs are: five times more likely to smoke marijuana; three times more likely drink alcohol; 12 times more likely to smoke tobacco; three times more likely to have access to marijuana within an hour and five times more likely to have access to it within a day; and nearly five times more likely to know a peer who uses illegal drugs (such as acid, ecstasy, methamphetamine, cocaine or heroin).

The complete survey findings were scheduled for release Thursday at a press conference at the Kaiser Family Foundation Building in Washington, D.C.

More information

The U.S. Substance Abuse and Mental Health Services Administration offers advice for keeping teens out of trouble.