A deadly epidemic apparently has emerged of teenagers sniffing butane, propane and other substances to get high, health-care workers reported.

The practice has claimed the lives of at least 20 youngsters in the Cincinnati area alone, including two earlier this year involving boys ages 11 and 15, said Earl Siegel of Children's Hospital Medical Center in Cincinnati. Research "leads us to believe that abuse of these readily available inhalants has reached epidemic proportions, indicating an urgent need for preventive efforts directed at teenagers and their parents," Siegel and colleague Dr. Suman Wason said in a letter to The New England Journal of Medicine that was published Wednesday.

The dimensions of the problem nationwide are not known because no central reporting system exists to document cases of deaths or injury from inhalant abuse, he said. But Siegel said his experience in Cincinnati indicates that known deaths across the country "are just the very tip of the iceberg."

Charles Sharp of the National Institute of Drug Abuse said that in Great Britain, where researchers have tried to systematically track sudden sniffing deaths "they record well over 100 a year."