Got a pacemaker? Be careful with that cell phone!
May 21, 1997
Web posted at: 8:10 p.m. EDT (0010 GMT)
WASHINGTON (CNN) -- Digital cellular telephones kept near the chest can disrupt heart pacemakers, according to a study involving nearly 1,000 people with the heartbeat regulation devices.
When the phones are held over the ear, the "interference does not pose a health risk," say the authors of the study, published in Thursday's New England Journal of Medicine. The problems only surfaced when the phone was next to the pulse generator.
Bruce Ryan said he tries to keep his cell phone at least 6 inches away from his pacemaker at his doctor's advice.
"I probably don't give it much thought, but I probably will a little bit more in the future, Ryan said.
The study noted that the newer digital phones are much more likely to cause problems than the older analog models.
Also, state-of-the-art pacemakers filter out cellular phone radiation better than earlier types.
A team led by Dr. David Hayes of the Mayo Clinic in
Rochester, Minnesota, explored the pacemaker interference
problem by monitoring the hearts of 980 volunteers as five types of hand-held cellular phones were activated at their ear and at portions of the chest or abdomen.
The phones caused detectable interference in 20 percent of
the cases and produced symptoms such as heart palpitations, light-headedness or dizziness about 7 percent of the time.
The doctors said the interference sparked potentially
serious problems with the pacemaker in 6.6 percent of the tests.
The type of signal emitted by the phone, the model of the cell phone and the make and model of the pacemaker all influenced the risk factor.
Three of the four digital telephone models tested produced most of the problems. The three were North American Digital Cellular, Time Division Multiple Access-11 and Code Division Multiple Access.
A fourth digital type, Personal Communication System-1900,
produced far less interference, as did the models that used an analog signal. Analog systems are becoming less popular because digital phones have superior performance.
It's estimated some 45 million Americans use cell phones.
While the cell phone industry says it is responding to health issues, critics say it's not happening fast enough.
The Food and Drug Administration said there is no specific information linking cell phones to health problems, but there's not enough information to say that there is no risk.
Correspondent Jeff Levine and Reuters contributed to this report.
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