Dear EarthTalk: OK, so are cell phones emitting dangerous radiation or not? If so, which phones are safer that others and what do we do to minimize exposure?

Dear EarthTalk: OK, so are cell phones emitting dangerous radiation or not? If so, which phones are safer that others and what do we do to minimize exposure?

— Luke Alderman, Santa Fe, N.M.

The jury is still out as to whether or not the radiation emitted by cell phones can cause negative health effects for callers. Mobile phones emit signals to communicate with cellular towers via radio waves, which are comprised of radio-frequency (RF) energy, a form of electromagnetic radiation.

The U.S. Federal Communications Commission (FCC) limits the amount of radiation any phone sold in the U.S. can emit to what it considers a safe level of 1.6 watts per kilogram of body weight (a measure of the energy absorbed by the body when using a wireless device). But some health practitioners are concerned that even this level of exposure may be too high, resulting in people unwittingly exposing themselves to potentially harmful radiation every time they make or take a call.

Such radiation is known to heat up living tissue it comes into close contact with by a fraction of a degree, but this level of temperature increase is less than that caused by exposure to direct sunlight, and the brain's blood circulation typically disperses this excess heat quickly by increasing local blood flow.

Some recent studies have found higher risks for brain and salivary gland tumors among people using cell phones for 10 years or longer, while other research has found little if any risk. Other research has looked at the reproductive, cognitive and sleep effects of RF energy at levels similar to what cell/smart phones emit. Results have been mixed. More studies are now underway to resolve whether or not cell phones are safe for people to use, but some electronics manufacturers aren't waiting around to cut down on the radiation emissions of the phones they make and sell.

If you are in the market for a new cell phone, check out the nonprofit Environmental Working Group's (EWG's) rundown on which of the thousand or so popular cell/smart phone models give off the most and least radiation. Levels vary widely, from as little as 0.3 to the legal limit of 1.6 watts per kilogram of body weight. Sanyo's Katana II, Samsung's Rugby, Nokia's 7710, and the Blackberry Storm, among others, get top marks from EWG for giving off lower amounts of radiation (in the 0.3 range). Meanwhile, more than a dozen different cell/smart phones (including some of the most popular models such as Motorola's Droid, Blackberry's Bold 9700, LG's Chocolate Touch and HTC's Nexus One by Google) are categorized as "worst" by EWG for giving off larger amounts of radiation (pushing the 1.6 limit). Apple's iPhone 3Gs is in the middle of the spectrum, leaking between 0.52 and 1.19, depending on usage.

Regardless of which cell/smart phone you use, you can minimize your exposure to RF radiation by taking a few simple precautions. For one, using a headset (these give off significantly less radiation) or speaker phone keeps the phone itself away from your head. Also, your phone emits far less radiation when used to text instead of call — and the phone isn't next to your brain when texting — so the more you tap (just not while driving, please!) instead of talk the better. Also, a poor signal (fewer bars) means that your phone has to work harder — and emit more radiation — to connect up to a wireless tower, so wait to make that call until you are somewhere with a stronger connection.

CONTACTS: FCC,; Environmental Working Group,

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