Why is it dangerous to be exposed to X-rays but not (or at least much less) dangerous to be exposed to radio waves?

Short wavelength, higher energy and greater penetrating nature of x rays makes them more dangerous compared to the radio waves that have longest wavelength range and lesser penetrating power.

Explanation:

Both radio waves and x rays belong to the electromagnetic spectrum. These two types of radiation travel at the speed of light. But the frequency of the X rays is much higher compared to the radio waves. Due to this, the x rays can penetrate deeper into the skin than the radio waves.

When the wave length is smaller, they rays carry more energy, like the X rays. This makes them interact with matter more prominently. Since radio waves have longer wavelength, they carry comparatively lesser energy, making their interaction with matter lesser.

So getting exposed to x rays is more dangerous than to radio waves.