Wednesday, 21 June 2017

Microwave Massacre! Is The Humble Microwave A Kitchen Killer?

Let's look at a common misconception about an item you'll find in almost every kitchen in the Western world, the humble microwave. Much of the fear surrounding microwaves emanates from the general public's wariness surrounding various forms of radiation. Whilst it's clear that "radiation" can be dangerous, it's vital to bear in mind that "radiation" is an extremely broad term even when we restrict it to radiation found in the electromagnetic spectrum, ignoring alpha and beta particles. This encompasses everything from radio waves to gamma rays right through visible light.

Alternative health quack Joseph Mercola will tell you that microwaves cook your food by irradiating it, which is about as accurate as saying a light bulb allows you to see your couch by irradiating it. He'll also tell you that any food in a microwave "absorbs the radiation" which then passes into your body, again about as accurate as saying you should expect your couch to glow for a little while after you turn the light off! That said, Mercola also says that your microwave could be leaking up to "400 Milli gauss" of radiation, despite the fact Milli gauss are a measure of magnetic field strength. Couple that with the fact that magnetic fields obey an inverse square law meaning the field strength falls off pretty quickly at a distance.

The website "Truth About Cancer" offers this stern warning about microwave ovens:

Let's focus on the cancer claims and the claims concerning the electromagnetic fields involved in microwave cooking. These fears seem to originate from the fact that microwaves use "radiation" to cook and obviously some forms of radiation are carcinogenic. Idiots such as "Dr" Josh Axe talks a lot in this video about the dangers of radiation, without seeming to have any knowledge that radiation includes all forms of visible light. He helpfully informs us that our bodies are like "buckets which fill up with toxins". Utter bullshit, even if EMF could be considered a toxin, which it can't. (If "Dr" Josh is a legitimate doctor I'm a fucking leprechaun.)

The types of EMF radiation that cause cancer are ionising radiation. What this means is radiation that has the requisite energy to liberate outer electrons from a chemical element. Ionising radiation causes cellular damage by stripping elements in the DNA of valence (outer shell) electrons. If you've done some chemistry you'll remember that it's valence electrons that determine chemical reactions.

To understand why microwave energy isn't ionising first let's look at the electromagnetic spectrum.  



The energy of EMF radiation is related to wavelength and frequency by the following relationships.


c=the speed of light, h= Planck's constant, f= frequency, λ= wavelength, E= energy.

So you should see clearly that the longer the wavelength the shorter the frequency and the lower the energy. So you should also see that microwaves carry considerable less energy than X-rays or gamma rays as their wavelength is much lower. In fact, microwaves have less energy than even visible light.

Next, as we are specifically concerned with radiation's effect on DNA let's look at the ionisation energies of the most common elements in the human body namely carbon, nitrogen, oxygen and hydrogen which are roughly 11.3 eV, 14.5eV, 13.6 eV and 13.6 eV respectively, and calculate whether a photon of microwave radiation has the requisite energy to ionise any of these elements. Before we do that there is something that is important to recall here. If an element has an ionisation energy of 10.0 eV then only a photon of 10.0 eV and above will ionise it. Two 5.0 eV photons incident upon the atom will not work, nor will five 2.0 eV photons. 

So let's do that calculation:

Clearly, microwaves don't have enough energy to ionise any of the elements commonly found in DNA by some magnitude.

So if they don't irradiate your food, how do microwaves work then? 


Inside your microwave is a magnetron which when activated generates microwaves which flood the food chamber. The result is a magnetic field. Water molecules are dielectric, because of the bond angle between the two hydrogen and one oxygen atoms that make up a water molecule, it has a positive end and a negative end. 

This means the water molecules in your food align along a magnetic field. If that field is rapidly oscillating then the water molecules rapidly oscillate too. This kinetic energy heats your food. This is why dried foods aren't affected in microwaves.

OK, so if microwaves are so safe, why are they so heavily regulated? 

Just because microwaves aren't dangerous in the way scare mongers like Mercola implies doesn't mean they can't cause some harm. The dielectric heating effect could also have some pretty nasty effects on certain watery or fatty parts of your body, especially your eyes. This is why the inside of a microwave is a Faraday cage which regulations insist is far stronger than it needs to be and why you can't open the door without triggering the stop mechanism on the magnetron. There's also the danger of steam being released from sealed packages. These dangers are minor, and pretty comparable to the risk of burning one's hand on a hot stove. In fact, I'd say oven injuries are FAR more common than the harm caused by microwaves.

But what about nutrients?

Many nutrients in food break down as a result of heating regardless of the techniques used, but the shorter cooking times of the microwave result in a reduce breakdown of nutrients. Couple that with the fact that many nutrients are water soluble meaning that the ability to cook without immersion in boiling water is extremely advantageous.  A  study at Cornell University showed that folic acid in spinach was reduced roughly 77% during stove cooking, whilst being virtually unaffected by microwave cookery.

Go and give your microwave a hug and say sorry. He won't bite you, or irradiate your genitals. Just stay away from the kettle... that bastard is evil. Seriously, look at it.