system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do we know for sure that cancer and other deceases aren't caused by being constantly exposed to small radiations from electronic devices and 3G, 4G, WiFi, LTE, Bluetooth-signals?

I am in no way trying to be ignorant. I am certain that scientific studies has drawn some kind of conclusion, but how do we know *for sure*? 

If you think about it, there are rarely times where you can enter a room and not being in the way of some kind of signal. It just crossed my mind, how heavily has this area been studied? 
    How do we know that testicular cancer is not a consequence of an electronic device constantly receiving signals from various sources? 

Best regards, and merry christmas!
gpt
Simple, cell phones/wifi/etc all emit either radio- or microwave radiation. These two types of radiation fall under the umbrella of non-ionizing radiation. Other types of radiation in this category are infrared and visible light. Ionizing radiation includes UV, x-rays and gamma rays as well as radiation from nuclear reactions. 

Now, what separates non-ionzing from ionizing? Well the former can't knock electrons from atoms and thus can't make ions. Now to cancer, cancer is a genetic mutation where the DNA that controls cell reproduction is damaged and runs uncontrollably. In order to have this happen, you have to mess up the bonds in the DNA, which means you need enough energy to strip away electrons. So its physically impossible for non-ionizing radiation to cause cancer. The worst thing that going to happen from cell phones use, etc.. is your face is going to get a little warm.