Scientists vs Myths: is food from microwave oven dangerous and why you shouldn’t place refrigerator next to your bed

13:20, January 26, 2017

UrFU researchers debunk the popular scientific stereotypes

E1.RU and UrFU continue the project Scientists vs Myths. In the frameworks of the project, UrFU scientists debunk various scientific and pseudo-scientific myths.

We already spoke about GMO, Space and Brain.

This time we will focus on the myths associated with household appliances. We will try to find answers to the questions: how microwave oven effects our health, where it is better to put a refrigerator not to suffer from insomnia, and what happens to a man when he is constantly using his mobile phone. To find those answers, we went to the Department of Electrical and Electro-Technological Systems of UrFU Ural Power Engineering Institute to meet a candidate of technical sciences Fedor Tarasov.

“Electromagnetic radiation is electromagnetic waves excited by different emitting objects - charged particles, atoms and molecules. Depending on the wavelength scientists distinguish gamma rays, X-rays, ultraviolet radiation, visible light, infrared radiation, radio and low-frequency electromagnetic waves”, said Fedor Tarasov.

“The effect of different types of radiation on the human is also different. Gamma and X-rays penetrate the human body, causing tissue damage; infrared radiation heats the body; we can not feel the radio waves and electromagnetic waves of low frequencies on which appliances work.”

MYTH 1: Food heated in a microwave oven kills brain cells and negatively affects digestion.

— The products in microwave oven are heated by the impact of powerful electromagnetic radiation of decimetric range; for microwave ovens, the wave frequency of 2450 MHz is used. Such high frequency radio waves penetrate the product and affect only the polar molecules (mainly water), and force them to move along the field lines of the electromagnetic field.

Such movement increases the temperature of the product, and it is heating not only the surface of the product, but also the structure as deep as radio waves can penetrate it. In microwave ovens, waves can penetrate products to a depth of 2.5 to 3 centimeters, and further heating happens only because of thermal conduction. The principle of microwave ovens is based on the work of magnetron, a device developed by the military, which then has been used in household needs.

Roughly speaking, magnetron is the generator of radio waves which propagate inside the microwave oven. All sides of the oven are completely protected by an electromagnetic shield, which prevents radio waves from going outside. We can say that modern microwaves are completely safe, because any appliance is certified; the certification test checks the tension created by electric and magnetic fields. If the unit meets all the standards, it is safe to use it at home. There is no data confirmed that the microwave ovens have negative effect on the brain.

Any electronic device including oven produces electromagnetic radiation, so it is not recommended to stay too close to it. Don’t put your head closer than a couple of centimeters from a running microwave oven, and you will be fine.

— If appliances work properly after the end of service life, does it mean that the manufacturer has done a good job, and you can continue using them?

— You still should monitor the service life period for some appliances, for example, microwave ovens. As I’ve already mentioned, they have a special screen inside, and as far as I know, the standard service life of it is about three years. This screen protects us from the waves produced by a magnetron. That is why instructions indicate that it is forbidden to place parts of the body or put animals inside microwave oven.

— The more power, the higher radiation?

— Indeed, the power capacity defines the level of electromagnetic radiation. However, all devices are being tested before they are launched to market. In order to calm yourself, you can request technical standards certificate (in Russia it is called GOST/ГОСТ) when buying a home appliance; every device should have it. The certificate includes information about the properties of the appliance and indicates which standards it meets.

MYTH 2: No-frost refrigerators are more dangerous than usual ones.

— No-frost refrigerators just have a fan that distributes air through the radiator. That is why there are no grounds to believe in some extra-powerful radiation. The only thing you should keep in mind, it is better to connect your refrigerator to grounding plug.

— However, people in the internet discuss the idea that refrigerators can harm health. They say you should avoid placing it next to bed.

— I can think of only one argument to support this statement: sometimes you can get hungry at night, which can break your diet; that’s why you shouldn’t sleep too close to your fridge :)

MYTH 3: You should not have your phone around when you sleep.

— As I’ve already mentioned, the main factor affecting the health, when we are talking about mobile phones and other household appliances, is the time we spend with these devices. Scientists have yet come to a consensus if it is harmful or not. It will take time, as the period we have been using them is too short to say for sure. There were a lot of research, which prove that radio waves produced by cellphone towers do not affect human health. However, it's better to limit the work with a cell phone. The less time you spend with the source of electromagnetic radiation the better. The most dangerous moments are when the phone is searching for the network; electromagnetic radiation becomes much stronger at this time. Before buying a suspiciously cheap phone make sure, it passed the mandatory certification. Sometimes it is better to pay more but get a reliable device.

— Is it ok to keep charging phone beside the bed at night?

— Again, the most important is the distance. Safety distance is about a meter; at this distance, any electromagnetic radiation from usual devices fades. Don’t put the phone under your pillow. When the phone is on charge, the radiation produced by the charger adds to the device electromagnetic radiation. Each device has an electromagnetic range. The most important thing is not to cross the lines among themselves.

MYTH 4: Induction stove makes food radioactive.

— It is a myth. Induction stoves operate on the following principle: the induction coil induces eddy currents directly in the cooker. The induction stove heats the container, not food. Thereby the effect of heat conduction makes the cooking of products possible, without affecting their structure and properties. Induction stoves does not make food radioactive.

— I heard that induction stoves are dangerous for people with pacemakers. Is it true?

— Yes, it is. Electromagnetic waves can affect the operation of pacemaker as waves can cross each other on certain frequencies. That is why people with pacemakers should not use such stoves. Industrial enterprises with induction devices limit access to such devices for people with pacemakers.

— If you make a list of the most harmful home appliances, how will it look? Will microwaves take the first place?

— I would not say so. The first place will take those devices you use a lot throughout the day. Usually they are computers and cell phones. Nowadays we can not imagine our life without them. Computers and cell phones are followed by home appliances, but I can not say which device is the most dangerous or the safest.

— Older people are suspicious about Wi-Fi and even connect their health problems to it...

— Wi-Fi is a relatively new technology, but in general, scientists agree that it is completely safe. Most likely, this fear stems from the fact that people tend to be afraid of all the unfamiliar. People were afraid of lightning, before they knew the nature of its origin. Nowadays we have the same situation; fears are born by ignorance.

After our conversation with the scientist, we go to a laboratory, where unique electrical equipment is being developed. You can not buy it in the store, this equipment is designed for plants and factories.

— In general, we are developing a special industrial electrotechnological equipment for transportation, electromagnetic stirring and crystallization of liquid metal. We study the effect of electromagnetic fields on the structure and properties of the alloy at the moment of crystallization.

— Now we are conducting induction melting of aluminum alloy. In this example, we use a special inductor to observe the effect of levitation melting - metal is melted in the air.

It is exciting and a little bit scary to watch such powerful induction installation in action. With the help of forceps scientist place a piece of aluminum, which is melting under the influence of electromagnetic fields; it changes shape, then glows like a burning charcoal. Installation is switched off and we can see how liquid aluminum flows down and falls on a special wool.

- This induction heating unit operates at a high frequency of several kilohertz needed to melt metal. The frequency is different from the one we have in the induction stoves for cooking, but the principle of working is very similar; it has the same type of induction coil, the difference is that the coil in the industrial installation is water-cooled, the one we have at home is not. In both cases, the coil induces eddy currents in the metal; here we had a piece of aluminum; at home, eddy currents would heat the bottom of the pan.

Many developments of the department of electrical and electro-technological systems are used at the enterprises of the Sverdlovsk region. For example, Kamensk-Uralsky metallurgical plant embedded induction magnetohydrodynamic pump for pumping liquid magnesium. This pump makes it possible to reduce the defect rate and energy consumption for remelting defective ingots.

Irina Akhmetshina, e1.ru