charlotte erith

Yes, there ARE studies showing that RF waves (and specifically, those from mobile phones) can cause various disturbances (e.g. to your immune system, your ability to sleep, and the risk of brain cancer). There are of course other studies that do “not conclusively” show such link; unfortunately the way these are presented by the cell phone industry implies that these studies have concluded that was no link. That’s inaccurate. (For a couple of studies, try searching Google for “884 MHz GSM”, or “RF” and “immune system”). In either case, given conflicting findings like these (as with tobacco), it is probably best for your own sake to apply the “precautionary principle”..

More to the point of your article, though: A phone’s SAR rating is, at best, a bit misleading. First, because this is something that manufacturers normally do at the behest of the FCC (the US agency that deals with communications), it is normally measured in (and only in) the 1900 Mhz GSM or CDMA bands. This is primarily useful for people in the USA, since this is the highest frequency band used by mobile carriers here. (Others include 800-900 MHz and 1700 MHz). In particular, W-CDMA (used to carry UMTS/HSDPA, a.k.a. “3G”) transmits over 850/1900 MHz in the USA, and 2100 MHz internationally. Further, because WCDMA radios transmit more RF than GSM radios, handsets that are US “3G” capable will inherently have higher SAR ratings than handsets capable of international “3G”, since the only signal measured in 1900 MHz on the latter type will be GSM signals. That does not mean that they are more safe; on the contrary, probably the opposite is true (given the higher frequency).

Bluetooth headsets are normally “Class 2″, i.e. transmitting at 2.5mW, while cellular signals are in the ballpark (depending on conditions, technology, etc) of about 100mW. On the other hand, Bluetooth frequencies are in the microwave range, close to the 2.48GHz resonant frequency of water (and so could potentially heat you up a little bit).

So is WiFi (it nearly overlaps with Bluetooth as far as frequencies go); and it typically transmits at 10mW or 100mW (the N95 has two options under Advanced Settings). This would potentially be even worse than plain old GSM signals if positioned next to your head, or at your bedside at night.