Microwave oven radiation

[Bill]

I find this interesting. Maybe someone here has some expertise or opinion in this area?

2 years ago a friend bought a microwave oven. He used to work maintaining things like scanners at a specialist hospital. He has a radiation meter, so he tested the radiation, which set off the alarm on the meter. He contacted the suppliers, who repaired it. The repaired oven still set off alarms. They replaced it. The replacement set off alarms.. He contacted trading standards, who referred the case to Yorkshire where the supplier was based. I assume his money was refunded. He heard no more.

He replaced the oven with one of a different make. It was fine until it died a week or so ago. He liked the timer on the radiating oven because it could be set accurately enough to heat his mince pies, and saw it was still available. Thinking they must have solved the problem after two years, he bought one again. He measured the replacement. The alarm on his meter goes off all around it at 5mv/sq metre, and full scale is 10mv/sq.m. It goes beyond full scale when held 2" from the oven.

He rang the suppliers, who just said that all their equipment was built to full European standards. They couldn't tell him what those standards were. He was then referred round in a circle and ended back with the supplier.

They referred him to the actual makers of the rebadged oven, Samsung. They have referred him to another organisation in Kendal. He has repeatedly rung them and spoken briefly, but been repeatedly cut off. They blamed their new phone system and he has latterly been unable to get through at all.

I've certainly never measured the radiation from our oven. Perhaps that explains her funny moods? (That's a joke in case my wife ever reads this).

[Jethro_uk]

Microwave radiation is non-ionizing.

[Broadback]

That means? to us peasants.

[Tim Streater]

That the radiation photons are not energetic enough to damage your cells, DNA, or anything else. And this is true no matter how many of them there are, i.e. no matter how much the needle zooms up the scale.

Of course, if such radiation is absorbed by your body you might boil to death. But not at 10mW/sq metre or whatever it was reading.

If you move up the electromagnetic spectrum from microwave, you eventually get to infra-red, then visible light, then UV. IIRC, it's somewhere in the UV band that radiation photons are energetic enough to do damage to your DNA etc, which is why you can get cancer from it.

[Martin Brown]

You can tolerate a little of almost anything. The dose makes the poison

- even for ionising radiations. We evolved on a planet with natural background radiation. People who work in unusually hot workplaces and also much less radioactive locations like Boulby potash mine are health monitored to see if there are any detectable effects with dose.

There appears to be a smallish dose that has almost no effect at all because our DNA repair mechanisms can keep up with it.

However, if there is a significant microwave leak then you can cook your insides or end up with early cataracts of the eyes. There was a nasty one with a chef leaning on the door of an industrial kitchen microwave that resulted in the door seal leaking badly and he lost a kidney.

I once walked into a lab where someone had a 1kW helium microwave plasma on the bench with all the safety interlocks defeated and no Faraday cage around it. Very pretty colour it was too but extremely bad for the eyes. He said it made tuning it easier. I expect he is blind by now.

Despite that I do know one or two former microwave link engineers who spent a lot of time near powerful transmitters who died young and of brain tumours so I wouldn't entirely rule it out. Weak thermal effects can cause proteins to refold into the wrong shape (eg. like egg white).

If you require it to activate chemistry with a single photon then it takes something shorter wave than about 400nm (purple).

[Jethro_uk]

It's entirely possible that some radiation is required as part of evolution ?

[mailbin]

Many years ago I was actively involved in non-ionising radiation exposure issues. Memory may fail me but I think microwave exposure limits were set to give a temperature rise of less than 1 degC, whereas lower frequencies were limited to avoid nerve stimulation effects (physical or magnetophosphenes) or corona. If anybody wants to know more the ICNIRP guidelines were/are probably the most authoritative source:

[tabbypurr]

You say radiation repeatedly, but radiation of what? Microwave ovens leak t iny amounts of ~2.4GHz rf, which is afaik harmless. It does however screw w ith a wide range of electronics, causing circuits to malfunction. I would n ot expect any modern microwave oven to be an rf hazard, but if you go back

40-50 years some certainly were.

NT

[charles]

There is also the point that cooking witha microwave is not something done

24/7. Your friend's meter alarm level was probably set assuming you were exposed to that radiation for a full working day.

[tabbypurr]

So far we have no idea what sort of radiation the meter detects.

NT

[Bill]

So, I take it that the general view is that the measured levels are nowhere near being dangerous in actual use. That's good.

Nevertheless, it appears that ovens are being made and sold that have external radiation levels well over double the apparent recommended maximum of 5mW per square cm (sorry about the error in units in the original post) at 2" away from any part of the device. This seems to be the Federal standard in the US. It is interesting that the other make of oven that he has been using gives negligible radiation readings on his meter. I don't know what his meter actually measures. It's also interesting that his attempts to query this with the manufacturer and/or importer and with trading standards seem to have fallen into a black hole. I would have expected Samsung at least to be able to point to the regulations and a source of some basic generic test data on what the general public might perceive to be a safety issue.

[Bill Wright]

Does anyone know how these numbers compare with the field strength crossing the body of a person stood on a hilltop 16 miles from Emley Moor? Or the field strength 30mm away from a smartphone (where your brain is)?

Bill

[tabbypurr]

All this is meaningless until you have some actual data. At this point we don't.

NT

[Tim Streater]

That's a smallish dose that has no effect at all as previously explained.

[dennis]

mV is a useless measurement for microwave radiation. What power does it leak and is it from the magnetron? In fact a radiation meter that measures mV is useless for anything I can think of.

[dennis]

But at what frequency as they are all different ones? What are you trying to imply with regards to this mystery radiation?

[Graham.]

Quite so. All the instruments I have seen for this purpose measure in mW/cm^2, so what the OP's friend's meter is for is anyone's guess.

[The Natural Philosopher]

Well field strength is volts per meter which is volts squared per meter squared which is watts per square meter.

[jrwalliker]

Yes - at least for my microwave oven. Last time I measured it (with an antenna and spectrum analyzer) the leakage from the oven was similar to the signal from an 1800MHz mobile phone transmitting at full power at the same distance.

John

[Brian Gaff]

To be honest, unless you are going to sit and cuddle the microwave for days, I'm not convinced the levels are that dangerous. Most of the meters you used to get were much less sensitive than what you say. In the main, radiation monitors are meant for higher energy radiation which is dangerous, like gamma for example, the fact that they work at other energies may well just be accidental.

It is interesting though that other makes show lower output of leaks. Normally any leaks show poor design. I always want microwave ovens to be made with metal sides, some are not I notice. Usually though the leaks tend to be doors and seals of doors. Brian