If you or someone you love has a pacemaker to regulate the heartbeat, you may have heard rumors that cellular phones are dangerous. But there's no need to throw out your cell phone.
In a recent study in the New England Journal of Medicine, physicians reported that although cellular phones can disrupt the electrical impulses of a pacemaker, they rarely cause any problems unless the talker holds the phone directly over his chest.
Physicians at the Mayo Clinic in Minnesota, the New England Medical Center in Massachusetts and the University of Oklahoma Health Sciences Center studied 980 people with pacemakers. They found that hand-held cellular telephones caused mild symptoms - irregular heartbeats, dizziness and shortness of breath - only 1.7 percent of the time.
And, even more reassuringly, the phones did not cause any symptoms when they were held over the ear, the way people normally use cell phones. The cell phones only durupted the pacemakers when they were held over the side of the chest with the pacemaker generator.
Problems with cell phones and pacemakers arise because the phones produce a small magnetic field that interferes with the electrical signals pacemakers send to the heart.
Digital cellular phones made with new, digital technology were more likely to interrupt pacemakers than phones made with older, analogue technology, according to the physicians' report.
Digital phones send invisible signals that are shaped like a staircase, while analogue signals are shaped more like a ramp. Just as pushing a wheelbarrow full of eggs up a staircase jolts and damages more eggs than pushing the wheelbarrow up a ramp, jagged digital signals cause more interference with delicate pacemakers than analogue signals.
A few other high-tech machines besides cell phones generate magnetic fields that can disrupt pacemakers' signals. Machines that use a lot of electricity - magnetic resonance imaging (MRI) scanners and high-powered welding equipment, for example - generate particularly large fields and are much more dangerous than cellular phones.
Overall, pacemakers are extremely safe and very reliable. The benefits of pacemakers far outweigh any minor nuisances such as remembering to hold the phone over the ear on the opposite side of the body as the pacemaker and not to carry the telephone in a pocket near the pacemaker.
A much more dangerous combination than cell phones and pacemakers is cell phones and cars. According to a study published in the Journal of the American Medical Association, people who talk on cellular phones while driving are four times more likely to have an accident than those who don't use cell phones.
So, if you have a pacemaker, you can relax - your cellular phone poses little threat to your health - as long as you don't drive while speaking on it.
Dr. Larry Chinitz is Associate Professor of Medicine at New York University School of Medicine.