According to European scientists who have concluded a four year long study of cellphone radiation (the same gigahertz level frequencies used in microwave ovens, by the way), cellphone radiation appears to cause damage at the DNA level in cells, and not all of it was repairable by the cell. This means you end up with mutated cells in your body, which is one suspected cause of some cancers. Scientists agree more study is needed. The cellphone industry has no response.