Current cordless phones/mobile phones have been recently found to have biological effects on the brain. There are currently no details on what exactly may be occurring biologically but the primary age groups this may affect are apparently adolescents and children. Although there is no proof for any health risks, this research is more of a precaution. The University of Örebro in Sweden is conducting this research so the providing a link to the direct source would require knowledge of the Swedish language. Therefore, start off with these English speaking links.
http://www.sciencedaily.com/releases/2009/11/091111121251.htm
http://www.alphagalileo.org/ViewItem.aspx?ItemId=62771&CultureCode=en