I spent a lot of years worrying about exposure to emfs but I have recently decided (for a trial period) to turn on the WiFi at my router so that my son can use facebook from his pda without going on a big computer. Do forum users think that WiFi is a danger as background exposure?

Absolute, unscientific, baseless tosh, I'm afraid.

I spent some time running a research establishment that did a fair bit of work on RF exposure and the effect on the human body. After exhaustive testing we concluded that there were some reasons to suggest that the UK/EU RF exposure limits might be set at a level that is slightly too high, but only by at most an order of magnitude, and even then no ill heath effects could be found - we were primarily following the precautionary principle and suggesting a limit we knew beyond doubt to be safe.

Wifi levels are millions of times lower than even our ultra-conservative findings.................

Most of that stuff quoted is mumbo-jumbo pseudo science, I'm afraid, and seems to be snipping bits from the 1950s/60s Russian work on cell-level observations (at field strengths way above wifi levels) that we double checked as part of our research in 1997/98.

Well if WIFI and 3G networks cause problems for humans, I am screwed! (Sat here, with my laptop running, 3 feet away from my mobile boardband (3G/GPRS) WIFI roughter. In the office I am surrounded by by computers, WIFI, 3G, GPRS etc. I can't get away from it!)

These days, you seem to be able to 'get' cancer from everything, so we are all doomed anyway!

^ are you sure that is not just a side effect of age

Oh yes, that one about staying up later! With two sprogs I've got to be in bed before 10pm.

Keith: JSH is completely right. These sort of stories are dreamed up by people, well-meaning or otherwise, who found maths and science at school boring and think that woolly feelings inside are a reliable substitute. Sorry, but no. You should see the Feedback page in the back of the New Scientist for more "fruit-loopery" in this vein.

The word "tosh" is on the mark.

Mobile phones pressed to your ear have field strengths far far higher than WiFi a few feet away from you. And so do leaks from your microwave oven, at a wild guess. The fact that mobiles and microwave ovens don't kill people outright is a strong clue that WiFi isn't any sort of risk at all, well no higher than exposure to dihydrogen monoxide falling from the sky; nasty stuff.

Rgds

Damon

FWIW, following our work on looking at possible portable radio/mobile phone field strength effects we did conclude that there was a very tiny possibility of some measurable short term biological effect (at the cellular level) from the RF field strength of a mobile phone held tight to the skull when at maximum distance from a base station (mobile phones adjust their transmit power automatically, so transmit maximum power when at maximum usable range from a cell tower) for long periods of time. Even then we couldn't find any evidence to support any impact on health, good or bad.

Personally, I tend to not use my mobile phone close to my head for long periods, just to be ultra-safe, but then a mobile phone signal is massively stronger than that from a wifi network - the RF field strength from a mobile phone held close to your head is many thousands of times stronger than that from a wifi router in the same room.

Just realised I'm sitting here with my hand on a wireless mouse typing on a wireless keyboard waiting for my mobile to ring. Every time I move my arm the wireless PIR sensor on the wall behind me transmits to the wireless buglar alarm in the cuboard. My wife has just arrived home and I think she accidentally zapped me with the wireless key fob for the car.

Do you think if I use a black desktop image on my computer monitor instead of the blue one supplied by Microsoft I might live longer?

Or better still

How many of us have tripped of a wire on the floor

We've been bathed in electromagnetic radiation for as long as we've been on this planet. The levels vary enourmously depending upon whether its day or night, inside or outside, the phase of the solar cycle, etc.

We've been transmitting radio & TV signals for a century or more. In some cases the signal strengths are relatively high, e.g. next to a regional TV transmitter, near Radio 4's Droitwich LW transmitter or with a mobile phone to the side of the head. In other cases the signal strengths are relatively low, e.g. distant radio stations or wi-fi boxes in other houses.

I'm aware of a lot of work being done on high field strengths, e.g. specific absorption ratio in the case of mobile phones. Its quite feasible to construct a room which is completely free of electromagnetic fields & just introduce a controlled source of radiation. Has anyone done any work to look at the effects of low field strengths?

David

<blockquote><cite>Posted By: fostertom</cite>

<blockquote><cite>Posted By: JSHarris</cite>Absolute, unscientific, baseless tosh, I'm afraid.</blockquote>You're too quick to say that, ST likewise. Every paradigm change in history is preceded by such statements; hitherto from stalwarts of organised religion, nowadays from true believers in the religion of Scientism. The meaning of the same data, the same honest research, can change over time. </blockquote>

A bit of background. Our work came about as a consequence of concern being expressed about possible unknown health impacts from the increased use of portable radio equipment, including mobile phones. The research we did started from the view that the old model of determining the safety (or otherwise) of any RF emitting equipment by measuring its ability to raise the internal temperature of an biological organism above a given level might not hold true. The question was first asked back when the former Soviet Union work on cell-level changes that had been observed in the presence of lower RF field strengths was published.

We started from a position where we were openly sceptical of the current safety limits, if you like, and we did get a fair bit of flack (particularly from mobile phone companies) for even daring to question the accepted wisdom re: allowable safe limits for exposure.

We tried extremely hard to detect changes in cells from RF exposure, and repeated some of the work the Russians had originally done, with similar results. We did find that some mobile phones could theoretically produce fairly high field strengths in the region of the skull around the ear, under certain conditions we suspect these levels may have been close to, or even slightly exceeded, the safe limit for continuous exposure.

We did find that mobile phones and portable radios created local RF field strengths in the human body that were orders of magnitude greater than those from any other source, due to the proximity of the antenna to the body.

RF field strength falls very rapidly with distance from the antenna, so, for example, a 1 watt mobile phone signal (and it's quite rare for a mobile to operate at a power as high as 1 W, it will normally modulate the transmit power down to a much lower level if it's within reasonable range of a cell tower) at a distance of 50 mm has a field strength of around 140 V/m, but move the phone to a distance of just 1 metre away and the field strength drops to about 7 V/m, a reduction of around 95%. At a distance of 5 metres the field strength has dropped to about 1.4 V/m, or about 1% of the field strength when held close to your head and at 10 m the field strength is down to about 0.7 V/m, or about 0.5% of that when held close to your head.

A wifi router has an EIRP of not more than 100 mW when actually transmitting data (many are actually a bit lower than this, plus they don't transmit data all the time - a laptop is typically around 30 mW maximum, for example). For the same distances as the example above, here are the approximate field strengths:

1 m from the router antenna ~ 1.7 V/m
5 m from the router antenna ~ 0.34 V/m
10 m from the router antenna ~ 0.17 V/m

Background RF field strength, from the sun and all the other big natural RF emitters in space, is much lower, around 1 pW average at the Earth's surface, but it is present all the time and over a very wide frequency spectrum, so the total "dose" is quite high, through life. Like pretty much any radiation (or medicine or poison, come to that), any effect of non-ionising radiation is probably dose-specific, so duration of exposure is as important as the magnitude of the field when looking at possible biological effects. Given the natural wide variation in RF field strength from the sun, in particular (it varies by an order of magnitude or more through the suns natural cycle), and given that we see no noticeable correlation between the suns natural 11 year cycle and health impact on the human race, it seems reasonable to conclude that any such effects are small and don't present a significant health risk.

Of course, if you believe that something has an effect on health, then in all probability it will. As has been shown many times, the power of the human mind to create physical symptoms when it believes in something is quite remarkable. It doesn't mean that the thing in question is good or bad though!

Thanks for all the feedback. largely as expected. Society does not go backwards and I think too many consumers are in too deep now to be able to reverse out.

Schools will be the battleground to watch I guess.

From my own perspective I have decided to turn it back off actually encouraged by my son after we both spent a bit of time researching on the web. Will adopt a cautionary approach. Meaning that I will switch it on occasionally and temporarily 'as and when needed'.

We should not forget that the green movement was born out of the concept of precaution!

To answer Davidfreeborough. We used to publish quite a lot on EMFs in the mag but it does not seem to be much of interest any more as it entails serious self-denial of gadgetry and technology. I thought cancers were on the increase not decrease? The only advances surely are that they have discovered ways of keeping people that have cancer alive for longer. And what about illnesses such as dementia where the causes are still as yet largely unknown.

Posted By: JSHarrisLike pretty much any radiation (or medicine or poison, come to that), any effect of non-ionising radiation is probably dose-specific

What if it's not, in fact sometimes, smaller the dose bigger the effect e.g. by the mechanism I outlined? Wd that change anything?

The really big challenge is proving causality, particularly where any impact on health is involved. I've always kept an open mind on health-related issues, because there have been far too many cases in medicine, in particular, where cause and effect have been incorrectly linked. As ST is fond of saying, "correlation does not demonstrate causality", yet we hear time and time again of people who do exactly this, particularly when it comes to diagnosing illness.

FWIW I too take a precautionary approach to RF emissions, I tend to avoid using my mobile phone, try to use it hands free when possible (which keeps the field strength right down around me) and I've always had a healthy respect for high powered transmitters, ever since working in an office that looked out on an airfield radar and being able to actually hear the radar PRF inside my head every time it swept around!

However, I've worked with a lot of people who were exposed to high RF field strengths for significant parts of their lives, and, unscientific as it seems, I can't see any difference between their health and those of friends who've not worked in such an environment.

When it comes to gadgets like wifi, Bluetooth, cordless accessories etc, then the field strengths are so tiny as to be negligible when compared to the big emitters around. For example, if you were to stand 15 m away from a 400 kV power transmission line, then the field strength would be around 1100 V/m, which makes the paltry figures from even a mobile phone held right against your head pale into insignificance (for comparison, a mobile phone at 15 m and 1 W is less than 0.5 V/m). Stand close to a big surveillance radar and you may well see field strengths many times greater than this.

Given that any health effect will almost certainly be dose-related, as I mentioned above, we should expect to see clusters of any adverse effects close to every high field strength location, yet years of analysis has failed to show any statistically relevant correlation to all emitters, let alone a causal link. The statistics of disease and ill health make things hard to analyse, anyway, I've been told (by my ex-boss who was an epidemiologist), because they are naturally "lumpy". Genetic predisposition, rather unsurprisingly, has a strong geographical correlation, making it very hard to determine cause with certainty, unless the link is fairly strong.

Posted By: fostertom

Posted By: GBP-KeithI thought cancers were on the increase not decrease?

five-fold - now why could that be?

"The number of global cancer deaths is projected to increase 45% from 2007 to 2030 (from 7.9 million to 11.5 million deaths), influenced in part by an increasing and aging global population"

http://www.who.int/features/qa/15/en/index.html

The rate of population growth over this period is similar:

http://en.wikipedia.org/wiki/World_population

David

Posted By: fostertom

Posted By: JSHarrisAbsolute, unscientific, baseless tosh, I'm afraid.

You're too quick to say that, ST likewise.

Even if WiFi is a danger to health that particular article/explanation for how it might happen is rubbish.