I’ve got a fun experiment for you.  Open your web browser or a new tab and navigate to the Google home page.  Now enter the search term “is my microwave oven dangerous”.  When the results come up – which should be in the neighbourhood of 1.7 million hits – take a close look at each heading that appears in the list.  I want you to count (without clicking on them) how many of those headings are answering ‘yes’ to your question, compared to how many are saying ‘no’.

When I tried it, the results were nearly 1:1, and amusingly, they appeared in an alternating pattern, with one claiming microwave ovens are deadly, followed by one claiming they’re perfectly safe, and so on.

 

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The order in which Google chooses to serve them up has no bearing on the topic, of course, but it does highlight the issue.  Since you now have that tab full of articles on the subject, you can undertake to inform yourself on the issue, or have a look at what Harvard Medical School has to say on it, or the World Health Organisation, or even the FDA.  I’m not inclined to add to that mountain of information and misinformation on the subject, but there are some interesting things that happen when people are exposed to microwave radiation.

There’s a contentious medical condition known as radiofrequency neurasthenia, or microwave sickness (MWS).  That second name may have been responsible for at least part of the public’s mistrust of microwave ovens, through a widespread misunderstanding of the science behind it.  I say it’s contentious because there are few scientists or doctors who agree on whether it’s real or not, which takes some explaining.

Scientists mostly agree that high levels of exposure to microwave radiation, as with any radiation can and will cause heat damage, such as burns, blisters, and even cataracts.  What they don’t agree is on what happens when the dose of radiation is much lower than that.

MWS is technically a syndrome, which includes a long list of symptoms ranging from fatigue, headaches, palpitations, insomnia, impotence, and blood-pressure fluctuations.  Now, we’re not talking about people who stood too close to their microwave oven while it burned their popcorn, the people who have suffered MWS were, in most cases, people who worked closely with powerful radio equipment for at least a decade or more.  And while their symptoms were most definitely real, the cause of them is still up for debate. (Hocking, 2001)

 

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Perhaps the most interesting symptom associated to MWS is dermatographic urticarial, which is more commonly known as skin-writing.  And it’s just as freaky as it sounds.  It’s characterised by a reddening and inflammation of the skin when scratched, rubbed or even slapped.  Which may sound fairly normal to you, but in this case, it’s even the slightest scratch that can cause a very well-defined, raised mark on the skin of the sufferer.  And that means that one can literally write on their body, with just their finger.

The underlying cause for the condition is unknown, but the mechanism seems to have something to do with a rare form of autoimmune malfunction.  People who suffer from skin-writing, apparently have weakened cellular membranes in what’s called their mast cells.  Mast cells are responsible for releasing histamine into the blood stream as an immune response to foreign bodies or antigens.  Those weakened cell walls mean that even the slightest contact with the skin can trigger the release of histamine, but without the presence of the antigens they’d normally attack, very much like an allergic reaction.  Essentially, those with dermatographic urticarial are allergic to touch, which is both amusing and depressing.

The thing is, if these symptoms are indeed caused by exposure to microwave radiation, it suggests a profound alteration of cellular structures caused by an interaction with the waves, perhaps in the same way that microwaves interact with water.  And to remind you, we are just ugly bags of mostly water.

 

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It’s important to realise that the radiation levels we’re talking about here are a few megawatts per square centimeter (mW/cm2) in the high gigahertz (GHz) frequency range, with near constant exposure over a period of ten to twenty years.  In comparison, your microwave oven is limited by law to 5mW/cm2, normally at a frequency of 2,450 MHz, at the surface.  In accordance with the square-cube law, that output will drop by a factor of 100, essentially 0mW, within five inches of the outer surface of the appliance.  So, if you’re looking to give yourself an effective dose of microwave radiation from your kitchen appliance, you’d have to surround yourself with several ovens within a proximity of about two inches, and run them for about eight hours every day for the next ten years.  And even then you might not suffer any ill-effects.

In the study of toxicology, there’s a standard idiom that says “the dose makes the poison”.  There literally is nothing on this planet (and perhaps in the universe) that cannot kill you if administered in the right dose.  Microwave radiation is one of them, but as with dihydrogen monoxide, there’s really nothing to fear.

Hocking, B. (2001). Microwave Sickness: A Reapraisal. Occupational Medicine, 66-69. Doi:10.1093/occmed/51.1.66

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