h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

What with the worries (and/or scare stories) over mobiles and now wireless networks, I was wondering what research had actually been done on health effects?

I was interested in the report:
http://news.bbc.co.uk/1/hi/magazine/6172257.stm
in which a teacher reckoned exposure to a wi-fi network had 'sensitised' him to mobile phones (which often work at a rather *higher* power level), as well as to satnav systems (which one would have thought didn't need to emit anything at all).

I remember reading something on the Beeb news site about a comprehensive independant study that had finally proved that mobile phones were not dangerous. I'll see if I can find a link.

Incidentally I told my brother about this and his response was that independant studies can't be trusted as they're always carried out by "one bloke in a shed"... shows how much he knows about scientific study, doesn't it?

I seem to remember a beeb news article a couple of weeks ago about a school refusing a wi-fi network as it might have adverse effects on the kids...

My first thought was "What, the same kids that spend half an hour every lunchtime with a cellphone stuck to the side of their head? And you're worried about a low powered wifi network.

Oh, and Sat Nav systems don't transmit - they receive... It's the satellites that are doing the transmitting... so if you were sensitive to satellite navigation systems the only way to avoid them would be to walk around in a metal suit all day. (Or live in a mine).

Regarding satnavs, my one uncertainty was whether there may be any advanced ones using a mobile-like (2-way) connection for real-time traffic updates, etc, though if there were, it would presumably have very little outbound information to transmit.

Personally, I could certainly feel the [presumably thermal] effect of my old mobile if used for more than a couple of minutes on a single ear - a very localised mild headache which would last for a few minutes.
However, thermal effects would rapidly become negligible with increasing distance from an antenna, or at lower power levels.

It would be interesting to experiment on self-declared ultrasensitive people and see what they really can or can't detect.

The wifi scare is typical luddite reporting, complete cobblers.
I mean, it's not like there's a huge amount of radiation streaming through the atmosphere, and us, constantly or anything. And has been throughout our entire evolution.

thermal effects of mobiles, nowt to do with holding a slightly warm anyway plastic (non absorbant) device up against your skin? I get the same symptoms from a handset on my deskphone and that doesn;t have any microwaves coming out of it.

I wish my wife was sensitive to satellite navigation systems...

>>"thermal effects of mobiles, nowt to do with holding a slightly warm anyway plastic (non absorbant) device up against your skin? I get the same symptoms from a handset on my deskphone and that doesn;t have any microwaves coming out of it."

I was referring to the thermal effect of absorbing radiation - localised heating of tissue. Obviously, if the antenna is moved away from the head, going from being a centimetre or two away to even a metre away, the drop-off in absorbed power is pretty drastic.

Ahh, magic moonbeams - my favourite subject In the UK, for many years the NRPB has published recommended safe limits for RF that enable you to calculate the safe radius around a transmitter. All big transitters have a so-called RADHAZ area where you can expect to be fried if you hang around inside it. Mobile phones, bluetooth, Wi-Fi transmitters etc etc are too feeble to even have danger areas.

Mobile phones are considered to be special case however because of their specific usage patterns (long periods in very close proximity); there are suspicions that there may be some poorly-understood health effect. So, despite being well within the (previously) accepted safe limits, phones are now required to be tested for specific absoption rate (SAR) - to determine how much power is actually transferred into a standardised human body. The pass limit is arbitrary, but I believe set at a very precautionary level. There has been a monumental amount of research into the health effects of mobile phone radiation. Since no-one has managed to demonstrate a clear risk to health, you *could* conclude (as I did) that any such risk must be tiny.

I doubt much research has been done on Wi-Fi networks specifically, but then why would you need to? If it is safe to eat a packet of crisps, then it is safe to eat a crisp.

If these people were really worried about radiation, they wouldn't go outside in daylight. I bought a house very close to a mobile phone mast; I get great reception and it keeps the idiots away from the area .

"I was referring to the thermal effect of absorbing radiation - localised heating of tissue."
And I was pointing out that the source of the thermal effect may be nothing to do with radiation from the phone!

One of the difficulties in researching the health effects of mobile phones is the wide variety of usage patterns. Someone who is on the phone constantly is going to have a different risk level than someone who uses it occasionally. Someone who keeps it always in the same pocket against their skin (cell phones still poll the nearby cell site from time to time even when not in use) will have a different risk level from someone who keeps it in a purse, on a table, or in different pockets.

Regarding RADHAZ... it reminds me of the urban legend of the radar technician at an early warning station in Alaska who huddled up under the dish for warmth. He was found hours later quite toasty.

>>"And I was pointing out that the source of the thermal effect may be nothing to do with radiation from the phone!"

Well, the short-term headache didn't seem to be on the surface of my ear, which was the only part of me in contact with the phone, but somewhat more internal.
It did move sides if I switched the phone around for ~> 5-10 minutes use on the other ear, but once I'd worked out what was happening, I started varying sides and position and/or holding it further away if talking in bad reception areas, where the phone would tend to be transmitting at maximum power.
Either the change of habits or a change of phone seems to have rather reduced any effects, and since I'm a very occasional mobile user, I guess if there were any serious problems, they'd affect other people before me, and they'd have affected many people already.

From Bob Park, a phsysicist (a good one IMHO):

2. CELL PHONES: FIVE YEARS LATER THEY STILL DON'T CAUSE CANCER.
A study in the current issue of the Journal of the National Cancer Institute found no increased cancer risk from cell phone use over a 20 year period. This is an update of a Danish study in JNCI five years ago. The Danes keep good records. By just going to the computer they could compare cell phone use with the National Cancer Registry. I was invited to write an editorial in the same issue, JNCI, Vol 93, p.166 (Feb 7, 2001). I noted that cancer agents act by breaking chemical bonds, creating mutant strands of DNA. Microwave photons, however, aren't energetic enough to break a bond. Predictably, fear mongers said there must be an induction period. Still waiting. In 1993, a man whose wife died of brain cancer was a guest on Larry King Live. Her cancer, he said, was caused by a cell phone. The evidence? "She held it against her head and talked on it all the time."

http://bobpark.physics.umd.edu/WN06/wn120806.html


I think cancer is right out. Other effects - I would like to see a study, double blind, where people are using/holding a cell against there head, and compare their symptons to people holding a cell that isn't using MW radiation but still gets warm.

It takes quite a lot of energy to heat something up - you have to put quite a bit of thought into designing a microwave array for cooking, and those run at hundreds of watts.

My wireless router, by comparison, is currently running at 28 mW, and I know that anything approaching a tenth of a Watt would break the damn thing pretty damn quickly.

I don't know how much energy a mobile phone transmits, but I would be very surprised if it was anything like enough to have a notable heating effect unless very tightly focused - whereas most mobile antennae are omni-directional, which is the complete opposite.

Just consider how much heat the human body outputs by comparison.

Your wireless router only needs to talk across the room. Cell phones need to talk to the nearest cell site, which is usually miles away. Cell phones can broadcast at up to 3 watts.

Still, you're not exactly going to pop popcorn with that kind of energy, are you?

People are generally very easily scared and think they know more about radiation than the really do.

I used to work in Nuclear Medicine (A6870729). The main part of that is injecting patients with radioactive tracers and then scanning them to see where it has gone.
While they were being scanned a lot of patients comented they were getting hot. Many of these patients were convinsed that it was the radiation heating them. For some no matter how much you explained that it was just their own body heat refecting back from the large white scanners and a little bit of the heat you get from any large electrical device they were still convinsed it was the radiation. They didn't seenm to realise they had actually been radioactive all the time since being injected, 3 hours for most.

My brain is protected by thick bone, which should hopefully keep it safe from radiation harm. But what about when I have my phone in my pocket, my testicles might be getting fried. The mobile does send out a location signal every now and then after all.

Well, your testicles are uniquely placed to cope with the heating effect.

Phones are now designed to emit most of their radiation away from the head when in use, so make sure you put it in your pocket with the aerial facing outwards. I doubt the odd ID bleep would be significant compared to a continuous connection though. Worst case, you'll save money on contraception

"My brain is protected by thick bone, which should hopefully keep it safe from radiation harm"

Well, maybe x-ray radiation - but what evidence do you have that it works at lower frequencies (e.g. microwave) ?


If it were possible I would implant a microwave transmitter of equal power to a cellphone in my brain, to prove that it doesn't cause cancer.

Traveller in Time trying to boil an egg in the microwave
"Most meat that leaves the microwave oven does not look alive to me. . .

The idea of microwaves to be dangerous is they cause heat not specifically cancer. "