What type of waves does cell phone emit and how does it affect us?

Radiation from cell phones is too weak to heat biological tissue or break chemical bonds in cells, but the radio waves they emit may still change cell behavior.Scientists exposed 10 female volunteers to radiation at 900 megahertz from GSM phones to simulate an hour-long phone call. 

They screened 580 different proteins in their skin cells and found that the numbers of two proteins were altered in all of the volunteers: one protein increased by 89 percent, the other decreased by 32 percent.This study shows that even without heating, molecular level changes take place in response to exposure to cell phone frequency electromagnetic radiation.

The awnser is b i believe