The finding, from the agency’s International Agency for Research on Cancer, adds to concerns among a small but growing group of experts about the health effects of low levels of radiation emitted by cellphones. The panel, which consisted of 31 scientists from 14 countries, was led by Dr. Jonathan M. Samet, a physician and epidemiologist at the University of Southern California and a member of President Obama’s National Cancer Advisory Board.
Studies of non-ionizing radiation impact on human tissue have been inconclusive to date, which is why the WHO can only say there is a "possible" danger. To be on the safe side, some of us minimize our mobile usage and use the speaker phone as much as possible.