DENVER -- A new study claims iPod music devices can interfere with the function of pacemakers.

The study, presented at the annual Health Rhythm Society meeting in Denver, says pacemakers in half of all the patients tested malfunctioned in some way when iPods were held to their chests. In addition, iPods caused significant electromagnetic interference in about one-third of those pacemakers.

"If the pacemaker is inhibited by the iPod and the patient does not have their own rhythm, they can be in serious problem," said Dr. Krit Jongnarangsin, a co-author of the study.

Jongnarangsin's co-author, Jay Thaker, of Okemos, Mich., first approached him about a possible link. Seventeen-year-old Thaker is a senior at Okemos High School and has been interested in connections between pacemakers and electronic devices for several years. His interest in iPods was sparked when a pacemaker-wearing patient of his father, a doctor, asked if it was safe to be around an iPod.

"We took patients from a pacemaker clinic, got consent, and we put the pacemaker programmer on them to view what was going on inside the pacemaker on a screen," Thaker said. "And then we took the iPod and held it about two inches above the implant site of the pacemaker."

Thaker and others involved in the study found various problems with the pacemakers. One device stopped functioning briefly and others picked up iPod signals and put them in their memories. About 100 patients were tested last year.

Thaker and Jongnarangsin admitted that iPods are not widely used by people with pacemakers. But they said patients could be affected if they're in close contact with those using the devices.

iPod interference is not considered life-threatening, but those involved with the study would like to establish a minimum safe distance between iPods and pacemakers.

"Whenever you do research, one study generates five more interesting questions, so we'll see where this takes us," Thaker said.