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AHHH i feel like im in my principles of radiography 2 class again!!! The inverse square law is different for my use, we need 4x more mAs to penetrate when we are doubling the distance!(which in essance is saying the same thing, we need more KV and more mAs to adequately penetrate the part - the farther away the SID the less power behind the radiation).
I hate the laws of radiation....too much to remember
You should be more worried about how many CT scans and xrays you have. One abd/pelvis CT is comparable to over 400 xrays! 
Anyways, i'm out of school for the day so no more radiation thinking from me01-13-09 06:09 PM - actually the radition emmited from the phone will eventually cause a benign bluetooth tumor to grow right on the inside of your ear!
honestly never thought about something like this...then again now that you think about it my head does hurt when I sit realllllly close to the microwave!
-just messin01-13-09 06:52 PM - You make 2 very good points. Allow me to retort.
All electrical things work by having two poles. A battery has a positive terminal (pole) and a negative terminal (pole). Often the negative is the ground. It is just the same with radiating antennas. There is the radiating part and the groundplane. Tower antennas have a real grounded groundplane. phones do this atrificially and siply create a different in potential between the two poles of the antenna. It would be much better if every cell phone had a good solid ground connection. This would be somewhat impractical.
The phone, not being able to leak to ground just sits there radiatating from every metal part. This includes wired headsets/headphones. It does not include bluetooth with its much lower power.
As branta say, energy cannot be destroyed so the radiated energy is simply absorbed by objects nearby. It simply heats up your ear by a tiny amount.
Early research was based purely on this phenomenon - heat. However more recent research has shown that the radiation itself causes symptoms in about 1 in 1-10000 people who experience very mild symptoms (mild headachers, mnausea, etc). Of these mild electro-sensitives, about 1 in 1000 of these are very or chronically sensitive to the radiation and suffer any number of nasty physical effects. A very, very, very few (I stress this) have contracted fatal symptoms. I am an engineer, not a doctor and I will not go further. IF you do not suffer symptoms, then my GUESS (and it is only that) would be that you may make reasonable use of your phone with impunity. If you suffer hearaches or any of the other documented symptoms then you should at once, change the way you use the phone AND seek immediate and competent medical attention.
It is like anythng else, if there is discomfort, stop doing it. We all move away from very loud noise or strong smells. It is just the same with your phone. If it causes discomfort, change your habits.
LAstly there is a community in Sweden where a number of hyper-electro-sensitives live and this village has no elecro-radiating applicances at all. Residents claim that their symptoms have entirely vanished.01-14-09 03:10 PM - You seemed to miss my point, although what you say is broadly correct. The grounding I had in mind is the grounding of a screening plate, like a partial faraday cage. If there is no grounding to the screen it simply re-radiates the incoming RF. This makes those clip-on mesh ear screens and similar "RF reducing" devices more or less useless as RF protection, although they might block a few greasy earmarks and they are really good for the seller's profit.You make 2 very good points. Allow me to retort.
All electrical things work by having two poles. A battery has a positive terminal (pole) and a negative terminal (pole). Often the negative is the ground. It is just the same with radiating antennas. There is the radiating part and the groundplane. Tower antennas have a real grounded groundplane. phones do this atrificially and siply create a different in potential between the two poles of the antenna. It would be much better if every cell phone had a good solid ground connection. This would be somewhat impractical.
To be strictly correct, the human holding an older phone is often the ground counterpoise at cellular frequencies and powers. The inductive coupling between chassis and hand is usually adequate, and completely harmless. The "interesting" emission is still radiated from the antenna, the counterpoise simply provides a stable reference which does not radiate. More of the modern phones seem to be moving towards pcb designs with multiband dipole type antennas which are self balancing.The phone, not being able to leak to ground just sits there radiatating from every metal part. This includes wired headsets/headphones. It does not include bluetooth with its much lower power.
Wired headsets shouldn't radiate a detectable signal under normal (non-fault) conditions. The cables are unlikely to be a tuned fractional wavelength so they will have high inpedance, they would only pick up a tiny portion of the RF signal, and they have a huge inductance (the speakers) to increase the impedance even more at cellular frequencies. You know this is true, because the headset doesn't buzz and rattle with the pulsed output signals, and the audio amplifier is not destroyed. And of course bluetooth units are micro transmitters at BT frequencies, but the BT power level is too low to get excited about and the radio link means there is no direct path for the cellular frequencies.
For the record, I found the BT power level spec.
Class 1, max 100 mW, min 1 mW
Class 2, max 2.5mW, min 0.25mW
Class 3, max 1 mW
It would be very unusual to find a class 1 headset.
For comparison, a handheld low band GSM phone will regulate power output between max 2.0 Watts, and minimum 20 mW. High band GSM runs about 3dB lower.
For 3G equipment this paper http://kom.aau.dk/antprop/pub/ExposureWCDMA.pdf seems to offer a sensible analysis.
Lurkers shouldn't get confused about the heating effect. Hot Phone Ear is caused by the phone getting warm because the transmitter is working hard and drawing a relatively high current from the battery. The RF emission does not directly make the phone hot, its the transistors and battery getting warm - the phone is more effective as a hand warmer than as a microwave.As branta say, energy cannot be destroyed so the radiated energy is simply absorbed by objects nearby. It simply heats up your ear by a tiny amount.01-14-09 06:43 PM
