There are two components used to describe electromagnetic energy; the frequency, and the amplitude. Walk outside on a clear day, and look around; a wide spectrum of energy is pouring out of the sun, and we can see the world around us by using our eyes to detect a part of that energy. If we stay outside for an hour without protection, elements of that same energy spectrum may burn our skin. If we look directly at the sun for an hour, our eyes will be damaged. It's all a matter of degree of exposure. A little sunlight on the skin can allow us to synthesize vitamin D from cholesterol. Too much will burn.
A gentle stream of water appiled for a short time will not harm you. Water at 3,000 psi can kill.
Being hit by fast moving rocks (alpha and beta particles from nuclear decomposition) is never good.
When it comes to electromagnetic radiation, you have to consider both the frequency, and the amplitude.
I don't always automatically accept the ditates of officialdom, by the way. We have been told by TSA that both millimeter wave (microwave) and backscatter (xray) machines are safe, so why have all of the backscatter machines been quietly removed? Please don't repeat the recently offered reason "people disliked the virtual disrobing" as both machines do that... The real reason (IMHO), is that in officialdoms eyes, the potential threat justified the means.
Now that there are enough millimeter wave machines available to go around, the backscatters are gone.