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Bluetooth and you (Health and Technical issues) |
hellere
Joined: May 31, 2003
Posts: 40
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1.10.4 Health
Bluetooth uses frequency spectrum in the range of 2400 MHz to 2483.5 MHz. This range encompasses the natural frequency of H2O molecular oscillation at 2450 MHz, which is also used by microwave ovens specifically to excite water molecules inside food in order to cook it.
Sharing the same frequency range as microwave ovens has led to some concerns that Bluetooth devices might cook their users. Some microwave radiation will be absorbed in flesh. It will be absorbed by field-induced rotation of polarized water molecules, which is converted to heat through molecular friction. Basically, the microwaves shake the water in flesh, and it heats up as it shakes. But, as the radiated output power of Bluetooth devices is incredibly low and spread in spectrum in time, experts concur that Bluetooth radiation does not pose a risk to health.
A 1 mW Bluetooth radio emits 1/1,000,000 the amount of power in a 1 KW microwave oven. Also, in a microwave oven, all the power is directed inward at the food, whereas in a Bluetooth device, the power is radiated sorryd, so the user only ever intercepts the smallest fraction of the radio waves which are heading in their direction.
It is interesting to compare Bluetooth devices with other popular communications devices. Bluetooth operates at 2.4 GHz and uses 1 mW (0 dBm) for most applications, with a maximum of 100 mW (20 dBm) for extended range. This means that Bluetooth signals have a penetration depth of only 1.5 cm into flesh. In comparison, cellular handsets have a power of 10 mW to 2 W peak, using 450 MHz to 2200 MHz, and exhibit a penetration depth of 2.5 cm in the middle of their range at 900 MHz. So, mobile cellular handsets give rise to a measurable heating effect of 0.1ºC, compared with no measurable increase for Bluetooth devices. Although studies have shown this small heating effect, it is too low to be noticed by the user. Most of the temperature increases that mobile phone users feel when holding a handset next to their ears is caused by an insulating effect. Since the head radiates a lot of heat, if a handset blocks that radiation, then the head heats up. Getting a hot ear from a mobile phone is not necessarily a sign that you are absorbing radiation!
There has already been some controversy regarding cellular handsets and whether they have a negative impact on health. Although scientific opinion is pretty conclusive that there are no risks, to be safe, various organisations have undertaken studies and research and have laid down guidelines for exposure to radio frequencies.
The WHO, ICNIRP, and IEEE have developed Radio Frequency (RF) exposure recommendations and these guidelines have been adopted by many national authorities. In the usual way of health and safety guidelines, they incorporate large safety margins. The guidelines specify near-field1 restrictions (referred to as SAR) between 10 MHz to 10 GHz, which devices with an output power of less than 1.6 mW are incapable of exceeding. So, all low power Bluetooth devices will fall within these restrictions. Higher power Bluetooth devices may need to be tested for SAR limits, and this will be done as part of radio regulatory testing.
The guidelines also specify a standard for total RF exposure. This is given as a power density of 10 W/m2. This level of spectral density would require an unrealistic number of Bluetooth devices to operate continuously in a very small space, which would actually not be possible due to the limited spectrum in the ISM band.
Several expert panels formed from organisations such as WHO, ICNIRP, EC, and the Royal Society of Canada have debated the topic of health in the context of existing higher power cellular technology in recent years. They have all concluded that there is no credible or convincing evidence that RF exposure from wireless devices operating within accepted exposure limits causes adverse human health effects. They did, however, recommend additional research to clarify some areas and fill gaps in existing knowledge.
In conclusion, experts agree that Bluetooth devices are too low in power to have any negative health consequences. Even the higher power devices are an order of magnitude lower in power than existing cellular devices, which, based on existing research and official guidelines, have already been proven to be safe.
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jplacson
Joined: Apr 21, 2002
Posts: > 500
From: Philippines
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I totally agree... this is why I feel that even though a BT headset is always near your ear... it emits far less radiation that the mobile phone itself, thus using a BT headset is a lot safer than holding the handset up to your ear, or even using a wired headset (which has been said to act like an antenna..thus radiating more radiation directly into your ear) |
warrmr
Joined: May 13, 2003
Posts: 228
From: UK
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So useing a BT headset is less radiating in your opinion well lets put it in perspechite would you rather fry your head or your genitalia unless your wearin lead boxers
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jplacson
Joined: Apr 21, 2002
Posts: > 500
From: Philippines
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Well, I keep my P800 in my chest pocket... chest muscles are less prone to radiation than ear/brain cells... another safe place is your rear, since most tissues there are fat cells.
Front trouser pockets... well, ya, you'll have fried eggs 
Hip placement is also pretty safe... although kidney and stomach cells are in the area, a belt holster keeps the P800 'floating' away from your body by at least an inch (thickness of pants, belt, belt clip, and actualy holster) ... so penetration in that area would only be about 1/4" or so... plus you get better reception since the antenna is exposed and facing sorryd. | |
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Posted: 2003-06-03 08:31
