Is It Safe to Carry a Cellphone in Your Shirt Pocket?

cell phone 
Is your cellphone harming your health?

Is it safe to carry a cellphone in a handy shirt pocket all the time over your heart? Can the constant or burst energy (one watt?) when a call comes in possibly affect the heart rhythm? What if your heart is a wee bit unhealthy in the first place?
Maybe hours on a cellphone is not a danger to your brain, but wearing a phone daily over your heart seems scarier to me. Any science about this?

Cellphones and portable media players do indeed produce measurable electrical and magnetic fields. But the strength of these fields will not affect ordinary heart rhythm or function, studies suggest. Various studies have also looked at whether cellphones and media players can present a danger to those with an implanted pacemaker, internal defibrillator or similar device. The results, for the most part, have been reassuring.
Problems may be most likely to arise when pacemakers and defibrillators are being programmed or reset by medical staff. Spurious signals from consumer gadgets may interfere with settings. Cellphones and players should therefore always be turned off under these circumstances.
Such signals could interfere with everyday function of heart devices as well. The good news is that the laws of physics dictate that the strength of the fields generated by cellphones and other electronic players falls rapidly with distance from the source. At the risk of provoking buried math anxiety, the “inverse square law” from high school physics states that if you double the distance from the source, for example, the field force drops four-fold (two squared), not just two-fold.
Practically, this means that to play it safe, we recommend that those that those with implanted devices such as pacemakers or defibrillators keep their cellphones and media players at least six inches from the generator and leads to minimize potential interference. This can be readily achieved by carrying cellphones in the pants pockets or on a belt or purse holster.
Meanwhile, those without implanted heart hardware can continue to enjoy music players and conduct cellphone conversations without worrying about potential deleterious effects on the heart from electrical interference.