High Temperature Risks
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 higher than its boiling point but without presenting any bubbles.
However, the boiling process can become "explosive" when the liquid is "disturbed", for example when you grab the container to remove it from the oven or when adding solid ingredients such as sugar. At this point there is a spontaneous boiling (nucleation) which may be sufficiently violent to cause the boiling liquid to overflow from the container causing serious burns.
Foods that simulate "closed containers", such as whole eggs (sealed shell), if heated in the microwave, can explode due to the increase in internal pressure of the steam. Likewise, plastic insulators of a plastic nature contain many air bubbles and are generally not recommended for use in a microwave oven; these, by melting and / or exploding, can contaminate the food / environment and exert a toxic effect on humans. Not all plastics lend themselves to this cooking and some tend to absorb microwaves until they become dangerous.
Products heated for too long can also ignite. This concerns any form of cooking; however, the speed and automatic nature of the microwave increases this kind of danger dramatically.
Risks of Metals Located in the Microwave Oven
Any metal or a conductive object inserted in the microwave acts as an "antenna" and produces electric current. This causes it to heat itself up, although this effect varies depending on the specific shape and composition; sometimes, this effect is used for cooking.
Any metallic object with a pointed shape (for example forks or crumpled foil) inserted 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 then forms a conductive plasma visible as a spark. The plasma and the ends can therefore structure a very effective conductive ring causing a spark of longer duration, therefore flammable. Among other things, when the dielectric air distribution occurs, some nitrogen and ozone oxides are formed which, in large quantities, are unhealthy for humans.
Some metal objects are compatible with the microwave oven, even if blind experimentation by users is not recommended. Generally, smooth metal objects without pointed ends, such as a shallow metal pan, will not produce sparks. Not surprisingly, the metal risers are part of the design of microwave ovens; moreover, the internal wall plates that allow lighting and air circulation 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 it, a stationary wave is formed. The energy is reflected back and forth between the tube and the cooking chamber. This can cause overloading of the hose and its combustion. For the same reason, dehydrated food or food wrapped in metal is problematic for reasons of overload, 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 objects that are likely to produce sparks are thermoses, holographic tableware (such as cups) and cups with a metal coating.
Extremely Fast Chocolate Cake - Microwave Recipe
X Problems with video playback? Reload from YouTube Go to Video Page Go to Video Recipes Section Watch the video on youtubeRisks of Direct Microwave Exposure
Generally, direct exposure to microwaves is not possible, as the microwaves emitted from the source are confined within it. To prevent it from escaping, the glass door is covered with a metal panel with holes that let in light, but do not allow the microwaves to exit. Therefore, there is no basis for the fear that it is dangerous to stay close to a functioning microwave oven.
Among other things, the ovens are equipped with redundant safety switches, which immediately remove power from the magnetron if the entrance door is opened. The tests in this regard have demonstrated the ability to confine the microwaves inside the ovens in such a universal way as to make routine tests on commercial instruments almost useless. According to the "United States Food and Drug Administration's Center for Devices and Radiological Health", the amount of microwaves that can escape from the oven throughout its lifetime is 5 milliwatts per square centimeter. This limit is far lower than the current level of exposure considered harmful to human health.
The radiation produced by the microwave oven is non-ionizing but does not present any risk of cancer associated with ionizing radiation (such as X-rays and high-energy particles). Long-term studies to assess the risk of cancer on rodents have not yet been able to detect any microwave radiation carcinogenicity to 2.45 GHz, even by means of chronic exposure (ie most of life). However, with the oven door open (which, as we have already said, does not correspond to a probable situation), microwave radiation could cause tissue damage from heating.
The microwaves generated by the ovens cease to exist once the power 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 changed differently compared to 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: Oven Microwave).
However, some cases of people who have been exposed to microwave radiation, both intentional and due to malfunctioning of the device, are mentioned in the literature.
Risks of Chemical Exposure
Some magnetron of microwave ovens have insulators of ceramic material and beryllium oxide ( beryllia ). Beryllium oxide, if crushed and ingested (for example, by inhaling dust), is a serious chemical risk factor for poisoning. Furthermore, it is classified as a human carcinogen, a concept confirmed by the "International Agency for Research on Cancer" (IARC). Therefore, ceramic insulators or broken magnetrons should NEVER be handled. Obviously, this is a real danger only if the oven is damaged and should not be a real concern during normal use.
