Although researchers have carried out scores of studies into the safety of mobile phones over the past five years, the scientific evidence today is no more conclusive than it was when Sir William Stewart published his first report in 2000. There are two main types of research: epidemiological studies, which look for health effects among mobile users and laboratory studies, which expose animals or human cell cultures to radio waves simulating phone emissions.

Scientists in Scandinavia, the leading region for mobile phone safety research, have found that such radiation affects cells growing in lab cultures and damages the brains of growing rats. But these experiments do not necessarily apply to people using phones in real life.