Motorola withdrew its funding from a study into the possible dangers from mobile phones and cell phone and phone mast dangers when it became obvious that exposure to digital mobile phone microwave fields both increased and reduced changes in damaged DNA.Some exposures worsened it, some inhibited it. The important point was that these changes occurred at non-thermal field strengths of 2-3 microwatts/gram, well below the 400-10,000 microwatts/gram allowed under current guidelines.

Ed.- Many scientists and national regulatory bodies still claim that it is impossible for any field to cause cell damage or alteration of biological function in humans unless it is sufficiently strong to heat the tissue.