Here are some of the biological changes caused by electromagnetic radiation, as observed and reported in various studies (most recent first):

Protein Changes in Skin. Ten women volunteered to participate in a study in which radiation (900mH) from GSM cell phones was applied to them for one hour to simulate a phone call. Scientists then screened their skin cells for any stress reactions. They looked at 580 different proteins and found two which were substantially affected. (One was increased by 89% and the other decreased by 32%). New Scientist February 23, 2008

Sperm Abnormalities. Researchers at the Cleveland Clinic studied the sperm quality of 361 men seen at their fertility clinic. On average, those who spent more hours talking on their cell phones had lower sperm counts and higher rates of abnormal sperm. (New Zealand Herald – Friday Feb 8, 2008)