A 1997 Australian study conducted at the Royal Adelaide Hospital on 200 mice produced convincing evidence that radio fields (in contrast to X- and gamma-rays, ultraviolet and atomic radiation) can directly cause the changes in genes responsible for cancer development. The experiment was conducted as a blind trial, using identical equipment and conditions for two groups of 100 mice. The mice were subject to GSM-type pulsed microwaves at a power-density roughly equal to a cell-phone transmitting for two half-hour periods each day; this was pulsed transmission as from a handset, not the steady transmission of a cell-phone tower. The difference between the two groups was that the power to one radio antenna was never switched on. A significant increase in B-cell lymphomas was evident early in the experiment, but the incidence continued to rise over the 18 months. (B-cell effects are implicated in roughly 85 percent of all cancers.) Over the 18 months, the exposed mice had at least twice the tumour rate of the unexposed.
An American study found that mobile phones held against the chest of people with pacemakers can interfere with their operation and disrupt the heart. Australian research showed that mice exposed to microwave pulses similar to those given off by mobile phones developed twice as many cancers as those which were not. Another line of research links incidence of brain tumours in humans with electromagnetic radiation fields produced by mobile telephone units.
A 1999 British study conducted by the University of Bristol claims that there appears to be a connection between temporary memory loss and use of cellular telephones supporting evidence that the use of cell phones can affect brain functions. The study was made on a group of volunteers who were exposed for 30 minutes to cellular telephone radiation and then underwent testing of memory and other brain functions. The ill effects were temporary and slight. The areas of the brain that were affected were those that deal with short-term memory, information processing, and heart and blood pressure function.