The National Centre on Addiction and Substance Abuse at Columbia University in New York also reported that 29 per cent of high-school students and 12 per cent of middle-school students knew of a classmate who had died in the past year from an incident related to alcohol or drugs; and 28 per cent of high-school and 19 per cent of middle-school teachers said they have had students show up for class drunk or high on drugs.
"While our schools used to be sanctuaries for students, many have become candy stores of dangerous substances - cigarettes, alcohol, inhalants, marijuana, heroin, cocaine and acid - sold or used by classmates on school grounds, " said Joseph Califano, former US Secretary of Health, Education and Welfare and president of the Center on Addiction.
The survey of 1,115 students aged 12 to 17 found that 35 per cent see drugs as the most important problem they face, up slightly from 31 per cent the year before. Social pressures came a distant second at 18 per cent.
Considerably fewer educators and other adults seemed to share their students' level of concern. Fewer than 20 per cent of teachers, 15 per cent of administrators and a quarter of parents surveyed agreed that drugs were American teenage children's biggest problem.
"To date, for most teens, attempts to provide drug-free schools have not succeeded," said Mr Califano.
"The solution is peculiarly in the hands of those on the school grounds - teens, teachers and principals - and those who should be more concerned about what happens on school grounds, the parents."