Non-ionizing radiation & biological effects

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I was wondering how waves of the non-ionizing part of the electromagnetic spectrum differ from each other besides mere frequency and more specifically with respect to possible biological effects. How does exposure of a human or other organism to for example radiation from visible light differ to that of radio waves?

An example: lately there seems to be a lot of fuss around possibly harmful radiation from cell phones, wireless internet etc., but why would that type of radiation be more dangerous than that of the sun, which produces irradiance of over 120 W/m², and moreover in a much higher frequency than that of radio waves (UV). How could the relatively small amounts of radiation from radio waves (2 W/m² at max) possibly be worse than sunlight (especially since generally there are no thermal effects induced by radio waves)?
 

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Drakkith
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Different wavelengths of light differ in several areas. First, the higher the frequency (shorter the wavelength) the more energy the light carries. (By light I mean EM radiation in general. Light is easier to type lol)

Also, the different wavelengths of light are absorbed and reflected differently. For example, radio waves can travel through many things, yet are easily absorbed by a thin amount of metal such as antenna. This contrasts to something like UV light which is absorbed by a relatively thin layer of ozone in the atmosphere. (Ozone is a gas that is transparent to visible light and radio waves)

In respect to people, your skin will block and absorb visible, infared, and UV light almost immediately. Radio waves will mostly go through you as will X-rays and Gamma rays.

Visible and Infared light do nothing to you except for heat up your skin. UV light is energetic enough so that when it hits your skin it can ionize electrons, turning molecules and atoms into ions. This has two effects. First, it can cause damage to your cells in general through free radicals, ions that will easily bond to another atom or molecule thanks to them missing an electron or having an extra electron. These can form harmful chemicals that can harm your cells.

Second, the UV light can directly Ionize the DNA in your skin cells, resulting in things like Skin Cancer. Now, the key here is to understand that UV light is the FIRST wavelength on the spectrum that has a high enough energy to do this. EVERYTHING under it, Visible, Infared, Microwaves, and Radio waves, CANNOT do this.

Cell phones use a fairly low power signal in the upper radio range to the lower microwave range. While some of this radiation is sure to be absorbed by your body, there has not been any conclusive evidence shown to link it to any kind of diseases or injuries. (Despite many believing it does)

While I cannot say for certain that long term exposure to low EM radiation of this kind doesn't have any negative effects, the fact that it CANNOT ionize anything greatly limits any possible damage it could do.

Also, while radio and microwave radiation can induce SLIGHT amounts of heating in your body, the effects are so miniscule that I cannot see how it would have any effect. Remember, your body is a living organism with blood flow and has ways keep a constant temperature. Like you said, sunlight heats you up way more than any cell phone would. Unfortunently the fact that radio and microwave can penetrate your skin makes many people worried.
 
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Thanks for your response!
 

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