For some people, hearing loss is not the only risk to watch out for when using headphones, as U.S. researchers found that earbud and clip-on type headphones used with MP3 players may also interfere with heart pacemakers and implantable defibrillators. A team at the Medical Device Safety Institute at Beth Israel Medical Centre in Boston carried out tests using 8 models of MP3 player headphones and 60 patients with defibrillator and pacemaker implants.
The research found that the powerful small magnets present in the headphones caused interference when placed on the chest within 1.2 inches (~3cm) of the devices with about a quarter of its patients, with the defibrillator twice as likely to give problems. With normal listening where the headphones are in the listener's ears, they were found to have no effect on the pacemaker or defibrillator. The MP3 players were also found to pose no threat to pacemakers and defibrillators.
Basically, this means that people with pacemakers or defibrillators need to be careful not to place headphones near the chest when not listening to them. For example a bad area would be to place headphones in a shirt or coat pocket near the chest. On the other hand, the researchers found that pacemakers and defibrillators usually return to proper functioning once the headphones are moved away from them.
Most of the tested headphones, which include models from Sony and Philips were found to have magnetic field strengths 20 times stronger than the threshold for interfering with pacemakers or defibrillators.
Further info could be read in this source Reuters story.
