Visible light, radio, television transmissions, microwaves, and X-rays are all examples of electromagnetic radiation, which comes in a variety of wavelengths and frequencies.
Radiation with wavelengths much shorter than visible light has enough energy to remove electrons from atoms in most cases.
This is referred to as ionizing radiation by scientists.
The shorter the wavelength, the more dangerous it is to living organisms.
Very short wavelengths, like X-rays and gamma rays, can quickly harm living tissue.
Gamma rays have so much penetrating power that several inches of a dense material like lead, or even a few feet of concrete may be required to stop them. Gamma rays can pass completely through the human body; as they pass through, they can cause ionizations that damage tissue and DNA.
Most mobile providers use radiofrequency waves in the 300 MHz to 3 GHz range, which are potentially detrimental to human health.