Recently I started using a bluetooth headset and out of curiosity I began to google the literature available on radiation emission from both cellphones and bluetooth headsets. There is not a lot of conclusive evidence out there. In fact, it is harder to find information on this topic than it is to find the latest specs of any cellphone! I thought of compiling it all in one place in case anyone has the same queries as me:
1. Cellphones emit 'non-ionising' RF (Radio Frequency) electromagnetic radiation. This type of radiation is also emitted by microwaves and is largely considered to be safe compared to the ionising radiation emitted by Gamma Rays or XRays. However, RF radiation can still heat up the tissues over prolonged exposure. Did you know (I didn't) that your eyes are the most likely to get damaged by RF radiation because the blood flow to the eyes is less and the body controls blood flow to dissipate heat from tissues. Luckily, we do not hold our cellphones to our eyes!
2. Given that we use our cellphones often, for long durations, and through our entire life, a lot of concern has been expressed as to whether this will cause damage or put us at higher risk for diseases like cancer. Research so far has been inconclusive on the matter.
The US FDA states in its website that "available scientific evidence—including World Health Organization (WHO) findings4 released May 17, 2010—shows no increased health risk due to radiofrequency (RF) energy, a form of electromagnetic radiation that is emitted by cell phones"
3. Precautions are still advised to avoid excessive exposure to radiation. The best method seems to be to use the speakerphone and always keep the handset far away from the body. RF Radiation can affect any part of your body that the phone touches. Basically, the further the phone is from your body, the less the radiation.
4. Using handsfree or Bluetooth still exposes you to radiation. In the case of bluetooth however, according to the Office of Information technology , California University, the RF radiation drops dramatically, to near zero levels.
In the case of wired handsfree, radiation can apparently still travel through the cable and metal connectors. An old CNN Health article suggested that a ferrite bead should be clipped to the cable, dropping the radiation to almost zero. I have never seen that one before, so here's an image from a vendor site, mercola.com
In any case, it is recommended not to keep a handsfree or bluetooth device on for prolonged periods. Use it only when you need to talk.
5. The level of absorption of cellphone radiation by the body is measured using SAR (Specific Absorption Rate). SAR is expressed as Watts per Kilogram, and the lower the value, the lower the radiation. This CNet article states that according to FCC Regulations in the US, the maximum SAR emitted by a phone should be 1.6 W/Kg. In Europe, the norm is 2 W/Kg. Surprise, we have no regulation for SAR in India as yet. According to Cellpassion, the DoT is contemplating a regulation along the lines of European norms of 2W/Kg. Fortunately, repuable companies publish SAR ratings routinely as part of specs, both online and in product literature.
CNet puts out an updated list of the 20 cellphones in US with highest SAR. While they are at pains to point out that this is not an indication that some phones are more harmful than others, the list is still an eye opener.
I think everyone should check out what their phone's SAR rating is. This is info we ought to know, as much as we know any other phone spec.