I'm having a continuous argument with a colleague of mine about the harm of microwaves. While he considers them harmful at any level, I tend to be caring less when the level is below -10dBm. We're talking about frequencies between 10 and 40GHz. I don't have a problem to have the coax to waveguide coupler open (and operational at -10dBm) while mounting gear at the network analyzer. Beside that a part of the -10dBm is reflected, I consider such little power is not harmful on the basis that sunlight coming with a density of 1kW/m^2 making 1mW/mm^2 is still orders of magnitude stronger than these -10dBm distributes over a radian or so. And we can stand the sunlight occasionally over shorter periods of time unharmed.
How do you guys regard that subject ? Strictly no exposure at no level at all ?
{BTW. I'm aware of the so called microwave solders in WW2}
AFAIK the only scientifically proven harmful effects of RF is heating. I have heard (anecdotaly, but not from a member of the tinfoil hat brigade) that this heating can happen in the brain without the victim noticing it
-- but certainly not at those levels.
But if someone is insisting on being afraid of invisible waves, you aren't going to convince them.
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What if the signal is OOK'ed at 3 or 5 pps, and gets rectified ionically in the brain, and the modulating signal is picked up at very low levels across billions of neurons, and triggers a seizure? Not saying it could happen, but...
FWIW they taught us that some RF bands are considered to be more harmful then the others (5GHz the worst), and the most sensitive parts of the body are the eyes and the endocrine system. Although the effect is essentially the heating, the protection was recommended when working with the levels of
+10dBm or higher.
Vladimir Vassilevsky DSP and Mixed Signal Consultant
Microwave exposure increases bone demineralization rate independent of temperature
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Dirk
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There are still no conclusive proofs that non-ionizing radiations - i.e. everything below UV - have significative health effects (besides heating, of course). Some studies may suggest some kind of correlation with specific diseases (e.g. child leukemia) but if the correlation was strong enough to be of any concern, I think we would already have a lot more evidence today.
Probably if you lower your average driving speed of 5 km/h, your survival rate will be improved a lot more than worrying about microwaves. :)
I actually asked Dr, Steve Edelson the question of whether or not that explanation was sufficient to account for the modern rates, at dinner together a while back. An unequivocal "NO!" is what I got. My daughter is profoundly autistic and, it turns out, the rates for that type of autism (which has a much longer track record) has also increased dramatically. At least, here in the US. I haven't read studies that may try to account for variations in methods and rates of identification elsewhere. It's possible that there would be something learned there. But within the US, it appears this can't be explained only by 'greater detection' (either a greater awareness by professionals or by a greater range of deficits being labeled as autism.) But it's a part of the picture.
Well, there is that. Lots of stuff in the news might be suggestive -- bisphenols, greater importation of foodstuffs (go to Costco, for example, and see where the Trio "health" bars are made) where food controls today probably aren't nearly what they have been here in the US even some decades back, of course the "mercury preservatives" debate still rages on, there is definitely a genetic component but also definitely a non-genetic component too from good, recent research coming out of Canada, and I even remember reading a convincing looking article showing geographical correlations of autism in the US with measured emissions profiles (I don't know what source they used for that) by coal-fired power plants (the article suggested Pb, I think.) I don't find it very persuasive, though, that your list of possibilities cuts much sway. There is too much money and interest in 'the system' now, top notch researchers are becoming increasingly involved, and most of the low hanging fruit has been picked at. The stuff you mention, each one I think, is low hanging fruit. Keep also in mind that one of the earlier correlations that was written about is that the parents of autistic children were more intelligent than the general public, at large, and with better incomes -- statistically speaking. I just don't think you got the answer nailed.
If you want to argue about this, focus on considering what used to be the "whole pie" but is today merely a subset -- profoundly autistic individuals. The identification of those individuals has been relatively unchanged for over 30 years .. perhaps more. The first time the term was used was perhaps in the late 1940's, I think. But the lists of deficits, check-off boxes, and processes for evaluating profoundly autistic individuals was very solidly in place by the time my daughter was identified at 2 years of age. And I'm told for some years before that. (Not to mention the fact that I've become quite an expert in my own right on that score.) These rates have similarly climbed rapidly and there is a much longer history of the rates.
I'm actually interested in good ideas on this score, though.
I'd only heard about bisphenol-A recently when Canada was in the news about planning to ban it -- a few months ago. I read a little bit. Most of the science about it seemed to suggest that it was very harmful, but mostly for those in the process of active development (axon and dendrite rapid growth, dendritic pruning, etc) of nervous tissue -- in other words, in humans prior to perhaps 5 years of age. It probably also has much more effect on some indicator species that live in or close to water ways. In adults, I'd probably agree with what you wrote. It's just that you seemed to have missed the fact that agencies weren't warning adults about their own consumption, but instead that of their young children as well as prior to birth.
There is a slight difference between incoherent white sunlight and coherent monochromatic radiation that also needs to be taken into account. Personally I would only worry about it if there was a risk of internal heating or of wearing a ring at the wrong resonant frequency.
OTOH A friend in the microwave telecoms industry died alarmingly young of a brain tumour.
Many microwave ovens are unable to adequately shield a mobile phone so the permitted leakage level cannot be exactly zero. Worth pointing out here that your WiFi is at worst case producing around 100mW of 2.4GHz or 200mW 5GHz (some can go upto 1W EIRP at 5.5GHz).
I once walked into a lab where a researcher was adjusting a ~1kW microwave induced Helium plasma on the open bench with all safety interlocks defeated by pieces of the right sized mesh. I remember wondering how long his eyes would last as I quickly left the room. Some universities played with this stuff in the 90's by cannibalising microwave ovens and flying on a wing and a prayer...
I was struck by how pretty translucent pinky orange the flame looked (compared to the dazzling 9000K optically dense RF induced Ar ICP).
Even if chemical A and chemical B are harmless if taken alone, this doesn't prove that chemical A+B will be harmless.
Food additives tests are done just like drug tests: by giving to animals or persons (depending on the trial stage) extreme dosages of a single chemical, and studying the effects. As far as I know, there isn't any real effort in finding possible new interactions with others chemicals (apart those already known in literature).
I mean the chemicals that you artificially put into food, from the field to the factory. Actually the wine is a very good example of this; grapes are one of the cultures most abused with pesticides, and several of them are already classified as mutagenic or toxic. Even if we take the leap of faith to believe that a carcinogenic chemical is almost harmless at a concentration lower than X (...), the problem of interactions between chemicals still stands, even at very small amounts.
This is a biased source, but it contains several interesting informations (all the site does, actually):
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If wines were subjected to the same limitations used for water, they would be all rejected. I don't know if laugh or stop drinking wine.
Of course not. Who have you taken me for, some kind of hippie? :)
I'm not one of those nutjobs/luddites/whatever that blame the tecnology for each one of their miseries, "chemicals are bad, let's ban them all and go live on trees!". IMHO chemical industry is the second great technological advance of our era, right after microelectronics. But just like we can't be scared of each technological improvement, we can't embrace it blindfolded either.
You can never prove a negative. You can only observe if there are any unforseen consequences when A+B are used together.
There are just too many permutations to test them all. One typical scenario is where people are self medicating with some random health food shop plant extract and taking a conventional prescibed medicine. Either on its own would be OK but both together and the kidneys give up the ghost. But in most of these cases neither A nor B is totally harmless - just tolerated without permanent damage at the dose level used.
I can think offhand of a few very simple combinations of A and B that would get you into serious trouble. Again neither of A or B are entirely harmless on their own but reacting them together is extremely bad.
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I think they are exaggerating. Hard to tell without knowing what analytical technique they used to identify and quantify the pesticides in the wine. I am surprised they didn't find any ethylene glycol ;-)
I get a bit fed up with the "ban all chemicals brigade". The website you quoted is an example. I favour minimum inputs farming where the pesticides are used as needed - I do not approve of hairshirt overpriced Organic(TM) produce that panders to the irrational fears of the worried well.
UK has a serious measles problem because of a falsely claimed autism link to the MMR vaccine. Herd immunity was broken in some areas and the children now pay the price by catching the real diseases.
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Cleanroom work seems to engender certain health risks too. Never clear to me why.
When I was in the USAF, one of the systems I worked on "ECM Pods" - a self- contained jamming transmitter that sticks to one of the airplane pylons.
When we finished one and buttoned it up, we used to check if it was radiating with our hand - if it feels warm, the pod is transmitting.
This was at levels over 100 watts.
The adverse effect of "microwaves" is heating, and not much more. I'd watch my eyes, though. (they don't like to be heated much).
I've heard about megawatt radar sites, where the antenna techs would carry along a little ball of steel wool. To verify that they system was off and safe, they'd throw the steel wool ball in front of the antenna. If the steel wool didn't burn, it was safe to work on the antenna. :-)
When I was in the Army we used to check the 440 mHz transmitter by touching the antenna too. I got tired of that trick and made up a detector with part of an airplane fin, a rod and some kind of lamp. Just to make sure the antenna was radiating and had good coax connections. That could not insure the transmitter was tunned to the right frequency, but it helped. When we shot off a drone aircraft it would keep flying if everythibg was OK. If not the chute would come out and cut the engine. Seems like the transmitter had around 100 watts. All about my RCAT life....
It didn't seem that long ago, the first and only cruise I went on was a small FUN ship in 1986. I thought I would cruise up to the radio room one evening and check it out. Well I have a 2nd class radiotelegraph license. I was suprised buy an old style station. really, a guy was using a straight key sending morse code. I look up the wall where the antenna feedline was and there was a light bulb in tune with the morse. I went back to crusin.
The thought had crossed our minds, but we never got that close. On the other hand, it'd be a cheap substitute for a vasectomy if you're done breeding, or if you're childfree by choice. ;-)
Of course you can, if you have a finite set of parameters. When the parameters are too much, you have two ways:
1) Make some sensible assumptions to preventively rule out most of them, then use statistics to confirm your assumptions (the so called "null hypotesis tests").
2) Improve analysis techniques (either by brute force - e.g. computerized simulation models - or not), so that you can make less arbitrary assumptions. Even if we can't test everything, it doesn't mean that there is no point in testing more.
The way (1) is widely used, but it has several practical and epistemiological (I hope that the english spelling is correct :)) limits. If the assumptions are wrong, it is very likely that the results will be contradictory or useless.
A silly example (but not too much): the use of the helmet when riding the bike. There are several studies that demonstrate that the helmet is credited for a significant reduction of bike injuries; there are several other studies that demonstrate that it hasn't any effect above statistical significance. These studies have been mostly conducted by universities and important organizations; how come that their results are opposite?
In the same way, one can't predict that he won't have an accident the next time he drives. But this doesn't mean that it's useless to improve your driving skills, to use the seatbelts (by the way, some studies deny also their effectiveness), etc. The unforeseen can't be ruled out, but it can be made less influent.
What do you mean? They have just sent some wine samples to commercial (and independent, I presume) laboratories, and asked to test them against the most common pesticides. How can it could have been more straightforward?
I know, you can lie also with good data and good statistics if you want to, but still...
I frequently make jokes on them. :)
In some italian health-themed newsgroups there was (or still is, I don't follow them anymore) a legendary netkook that supported almost every "natural" cure and conspiracy theory involving chemicals, from the most popular (SLS, mercury into vaccines, etc) to the most disturbing (urine therapy, curing cancer with sodium bicarbonate, etc). Well, years ago some clever group participants make him believe that there was this deadly chemical, present in huge amounts in food, air and rivers (even in Antarctica, below kilometers of ice!). Easily absorbed by human body, it could kill a man (or even an elephant!) in few minutes: the dreadful "dihydrogen monoxide"! He took the bait and wrote a concerned article on its site, with some expert proposals on how eliminate this horrible substance from your body by using natural medicine.
It is worth looking closely at any that might be expected to be tricky. But you cannot realistically hope to prove that for every possible permutation of even a three component mixture that there is not one dangerous one.
Famously there was an A level school science experiment on eutectic mixtures that had such a sting in the tail. It actually required an odd sequence of events to trigger including leaving the mixtures over a weekend in sunlight but eventually it happened and one mix exploded after an organic peroxide formed.
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Usually one lot a sponsored by the freedom to be stupid brigade and the other by manufacturers of safety helmets. It is even more bizarre for seatbelts. I would charge anyone injured through not wearing a seatbelt for any cosmetic surgery needed because of their own stupidity. Freedom to act stupidly comes at a price. I would also reduce the explosive charge in US airbags to be sub-lethal for small women and teenage drivers.
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The ones that claim seatbelts don't help are definitely in the lunatic fringe. Rally or racing car 4 or 5 point restraint harness would be better still. You can contrive a situation where they are damaging but compared to the horrific injuries people incur when unrestrainted limbs go out through car windows as the car rolls or someones head goes through a laminated windscreen and is garotted on the recoil. The latter happened at the end of my road - very messy.
I was an unrestrained back seat passenger in a serious car smash once. Now I always wear a seatbelt. The driver wearing his seatbelt incorrectly suffered internal bleeding, but the front passenger wearing a seatbelt correctly went on to have lunch.
I doubt if Ronaldo would have walked away from his wrecked Ferrari yesterday had he not been wearing a seatbelt.
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It isn't that easy to do ultra trace organic chemical analysis in complex matrices like wine and they have an incentive to report any false positives as true detections. Without knowing the methodology employed it is hard to decide whether their claims are genuine or simply a reflection of systematic failures in the analysis procedure. The most sensitive ultratrace methods are at best semiquantitative and you need to know the instrument detection limit for the method(s) used.
The exposure does not bother me in the least. The potential damage to the (possibly very complex) signal generators does. I have read some quality work about microwave exposure biophysics, that does not make me an expert though.
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