If we take a look at the electromagnetic specter, microwave wavelength is higher than infrared, which means its energy is very small. To break chemical bonds, the energy required is 100-1000 kJ/mol, and this kind of energy can be afforded only by UV and VIS. Due to this, we can conclude that microwave radiation has only a vibrational effect on molecules of food and does not break any bonds ( the food remains the same ).

Considering those facts, why is the microwave avoided in concern for health?

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    $\begingroup$ No more dangerous than normal oven. $\endgroup$ – Mithoron May 6 '15 at 23:44

If there is no concern over the quality of the food, I'm guessing the question is more specific to whether the microwave oven is a safe piece of equipment to use.

The U.S. Food and Drug Administration says:

Manufacturers must certify that their microwave ovens comply with strict FDA emission limits. The emission limits are well below the threshold for risk to public health. Most injuries related to microwave ovens are the result of serious thermal burns from hot containers, overheated foods, or exploding liquids.

There have been extremely rare instances of radiation injury due to unusual circumstances or improper servicing.

If we're not talking about the oven itself, and rather the nature of chemicals involved with its use, then we could talk about microwaving with plastics with foods. There are sources online that raise concerns over plastics leeching dangerous chemicals into the food.

Harvard School of Medicine says:

  • If you’re concerned about plastic wraps or containers in the microwave, transfer food to glass or ceramic containers labeled for use in microwave ovens.
  • Don’t let plastic wrap touch food during microwaving because it may melt.
  • Wax paper, kitchen parchment paper, white paper towels, or a domed container that fits over a plate or bowl are better alternatives.
  • Most takeout containers, water bottles, and plastic tubs or jars made to hold margarine, yogurt, whipped topping, and foods such as cream cheese, mayonnaise, and mustard are not microwave-safe.
  • Microwavable takeout dinner trays are formulated for one-time use only and will say so on the package.
  • Old, scratched, or cracked containers, or those that have been microwaved many times, may leach out more plasticizers.
  • Don’t microwave plastic storage bags or plastic bags from the grocery store.
  • Before microwaving food, be sure to vent the container: leave the lid ajar, or lift the edge of the cover.
  • $\begingroup$ So did I understand right this, if the microwave emits radiation as it should ( with low energy ), then its no concern. But manufactures 'abuse' by selling microwaves with high energy and then it hits us ? $\endgroup$ – Ndrina Limani May 6 '15 at 23:31
  • $\begingroup$ When you say radiation, do you mean inside of the microwave, or outside? The radiation by definition should be low in energy, but could be high in intensity, with a high powered oven. But, even then, manufacturers, at least in the U.S. are required to meet guidelines on emissions (radiation escaping the oven). $\endgroup$ – John Snow May 6 '15 at 23:46
  • $\begingroup$ Inside of course ! $\endgroup$ – Ndrina Limani May 6 '15 at 23:47
  • $\begingroup$ So there's no 'abuse' if it stays inside of the oven, high or low power. Does that answer your question? $\endgroup$ – John Snow May 6 '15 at 23:48
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    $\begingroup$ Well the Cancer Council disagrees with that statement. But the second part of my answer addresses concerns of cancerous chemicals leaching out of plastics. $\endgroup$ – John Snow May 7 '15 at 0:01

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