RISKS OF THE MICROWAVE OVEN

Risks of High Temperatures

If treated in the microwave in containers with a regular surface, homogeneous liquids can undergo a real "overheating". That is, the liquid reaches a temperature slightly above its boiling point but without any bubble formation.

However, the boiling process can become "explosive" when the liquid is "disturbed", for example when grasping the container to remove it from the oven or when adding solid ingredients such as sugar. A spontaneous boiling occurs at this point. (nucleation) which may be violent enough to cause the boiling liquid to overflow from the container causing severe burns.
Foods that simulate "closed containers", such as whole eggs (sealed shell), if heated in the microwave, can explode due to the internal pressure increase of the steam. Similarly, the expanded plastic insulators contain many air bubbles and are generally not recommended for use in a microwave oven; these, melting and / or exploding, can contaminate the food / environment and exert a toxic effect on humans. Not all plastics are suitable for this. cooking and some tend to absorb microwaves until they become dangerous.
Products heated for too long can also catch fire. This concerns any form of cooking; however, the rapidity and automatic nature of the microwave dramatically increase this kind of danger.

Risks of Metals Placed in the Microwave Oven

Any metal or conductive object inserted into the microwave acts as an "antenna" and produces electric current. This causes it to heat up itself, although this effect varies according to the specific shape and composition; sometimes, this effect is used for cooking.
Any pointed metal object (such as forks or crumpled foil) placed in the microwave can create an electric arc. In practice, an energy field is produced that delivers high concentrations of charge towards the extremities, determining the dielectric distribution of the air, at about 3 megavolts per meter (3 x 106 V / m). The air therefore forms a visible conductive plasma like a spark. The plasma and the ends can then structure a very effective conductive ring causing a spark of longer duration, therefore flammable. Among other things, when the dielectric breakdown of air occurs, some nitrogen and ozone oxides are formed which, in large quantities, are unhealthy for man.
Some metal objects are microwave compatible, although blind experimentation by users is discouraged. Typically, smooth metal objects with no sharp ends, such as a shallow metal pan, do not produce sparks. Not surprisingly, the metal raised grids are part of the design of microwave ovens; moreover, the plates of the internal walls that allow the illumination and the circulation of the air are all made of conductive metal.
Another danger is the resonance of the magnetron tube itself. If the microwave oven is started without an object that absorbs the radiation inside, a "standing wave" is formed. Energy is reflected back and forth between the tube and the cooking chamber. This can cause the pipe to overload and burn. For the same reason, dehydrated food or food wrapped in metal is problematic for overload reasons, even without necessarily being a risk factor for fire (the famous sparks).
Even certain foods, such as grapes, if inserted improperly, can produce an electric arc and increase the risks mentioned above.
Other items that are likely to produce sparks are thermos, holographed tableware (such as cups) and metal-coated bowls.

Risks of Direct Exposure to Microwaves

Generally, direct exposure to microwaves is not possible, as the microwaves emitted by the source are confined within it. To prevent them from escaping, the glass door is covered with a metal panel with holes that let in light, but not allow microwaves to go out. Therefore, there is no basis for the fear that it is dangerous to stay close to a working microwave.

Among other things, the ovens are equipped with redundant safety switches, which immediately remove power from the magnetron if the entrance door is opened. Tests in this regard have demonstrated the ability to confine microwaves inside ovens in such a universal way that routine tests on commercial instruments are almost useless. According to the "United States Food and Drug Administration" s Center for Devices and Radiological Health ”, The quantity of microwaves that can escape from the oven in its entire life of use corresponds to 5 milliwatts per square centimeter. This limit is far below the current level of exposure considered harmful to human health.
The radiation produced by the microwave oven is of the non-ionizing type but does not present any cancer risk associated with ionizing radiation (such as X-rays and high-energy particles). Long-term studies to evaluate the risk of cancer in rodents have not yet been able to identify any carcinogenicity from microwave radiation for 2.45 GHz, even by means of chronic exposure (ie much of life). However, with the oven door open (which, as we have already said, does not correspond to a likely situation), the microwave radiation could cause tissue damage from heating.
The microwaves generated by the ovens cease to exist once the electrical supply is disconnected. They do not remain in the food and do not make it radioactive.

There is some evidence that the nutritional content of certain foods is modified differently than traditional cooking, but there is no correlation to health problems or negative events associated with the consumption of foods heated with the instrument (see also the article: Microwave).
However, in the literature there are some cases of people who have been exposed to microwave radiation, both malicious and due to malfunction of the appliance.

Risks of Chemical Exposure

Some microwave oven magnetrons have ceramic insulators and beryllium oxide (beryllia). Beryllium oxide, if crushed and ingested (for example, by inhalation of dust), constitutes a serious chemical risk factor for poisoning. In addition, it is classified as a human carcinogen, a notion confirmed by the "International Agency for Research on Cancer" (IARC). Therefore, broken ceramic insulators or magnetrons should NEVER be handled. Obviously, this is a real danger. only if the oven becomes damaged and should not be a real concern during normal use.