Hy everyone,
The investigations for the biological effects of microwaves are the major concern because modern life is surrounded by electromagnetic waves which led us to frequent exposure every day. Pieces of evidence provided by scientists suggest microwave has a good, bad, and neutral effect depending on the frequency, power density, and biological sample.
But it is still unclear to make one statement: mostly microwave is good, harmful, or neutral for biological systems?
There is no one answer. It is like asking "Is stone good, harmful or neutral for biological systems?".
Let me try to expand on Malcolm White answer. I too think that your question is not very precise and therefore an answer to your question is not really possible, since you also mix different terms like electromagnetic waves and microwaves. As you probably aware, microwaves are a subspectrum of electromagnetic waves. Definitions of this spectra (in terms of frequency and wavelength) vary, but most draw a line bellow 1 THz (For most RF engineers every thing above 10 GHz is mm-Wave, but that doesn't matter). Now let's come back to Malcolm White answer. His analogy fits pretty well. To determine if a rock can be harmful you need to ask two main questions how big is it and how fast is it coming at you. You need to ask the same questions with electromagnetic waves. Here you have to ask what wave length does the electromagnetic wave have and what is the radiation power. To understand this you need to know how electromagnetic waves can interact with materials (also organic materials). There are two main principles at work: Ionization and restive loses. The first one is really bad for organic systems, but I can put your mind at rest. Due to quantum physics, a photon can only ionize if it has enough quantized energy (e.g. the frequency/wavelength is high/small enough) . And electromagnetic waves only posses such an energy quanta at high enough frequency (e.g above the visible spectra like UV and gamma rays) which is above 800 THz. Therefore there is no microwave source that is able to ionize organic matter. No lets come to the other aspect the radiation power and restive losses in materials. As you are aware you can use microwaves to heat up food. This happens by bringing the molecules in your food in resonance (this can only happen at certain frequencies e.g water at 2.4 GHz). The molecules are very lossy resonators and convert the energy in heat. Therefore if you hit a certain frequency and radiate enough power your losses are great enough to heat something up (which can be harmful). But to put things in perspective a microwave generates about 2000 Watts for a small chamber while your Wifi router only generates a maximum of 4 Watts for your whole house. To close my answer I would like to point out that at least humans also need some exposure to light, which is also an electromagnetic wave, in order to produce vitamins.
Best regards
For the human body, microwave radiation is harmful, no questions. The effect depends on the intensity of this radiation and the time of exposure. The amount of energy absorbed can be calculated when tissues parameters are known, but it is only approximated values in most cases. However, with low power levels, microwave energy can be helpful, for example, low power microwave medical imaging.
For me, I have a very simple comparison that we use every day in our kitchen: the microwave oven. It's up to you to make the link: Power + Time according to what you heat or cook. Good brain-storming.
This is an everlasting discussion since more than 80 years. There are about 15000paper which say that there exists dangerous subthermal effects and 25000 paper which say that there is nothing below thermal effects (with a few exceptions like the microwave auditory effect)..now you may select..Maybe is like the chinese water torture..30 liter of water as a shower in 5 minutes are good , healthy etc..But the same dose as a drop every 10 seconds on the forehead drives you crazy after a few days
Yes, there is a strong correlation between microwave signals and biological systems. Intentional/Unintentional continuous exposure to electromagnetic waves from high-power radio, radar, and wireless transmitters cause radio frequency hazards. The induced power density of the radio frequency signal triggers an increment in internal body temperature, which is aggravated due to the presence of highly sensitive heat sensors in the skin. If the generated wavelength is a multiple of the person's height, then the person could resonate like a λ/2 or λ/4 antenna and develop a higher internal field.
For many years of work in microwave engineering and medicine, I did not see any noticeable resonances in the human body due to RF exposure. It is because of the huge loss and multilayer structure of internal tissues. There are many internal reflections that occur at different distances. Rising the skin temperature is a very rare case and requires high power energy due to the relatively low dielectric constant and volume of the skin and adipose layers. Most of the energy loss in this area is determined by reflections rather than thermal effects. microwave energy raises the temperature of water-filled tissues and cells because of the high, about 80, dielectric constant of water. Actually, it is not pure water, it is a solution that close to urine, therefore, the dielectric constant is slightly lower than for pure water. Insider these thick and liquid-filled tissues power loss is mostly dictated by energy spreading and temperature may elevate. But resonance effects are practically not possible inside these tissues. Also, resonance requires half-way distance, never quarter-wave.
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