A long-term study finds that cell phones do not increase the risk of certain brain cancers during the first decade of use, though what happens beyond that is not yet known.
The study, published in the British Journal of Cancer, focused on the risk of acoustic neuroma, benign tumors which grow in the nerve -- close to where handsets are held -- which connects the ear and inner ear to the brain. Researchers have investigated the possible association of other kinds of brain tumors with wireless phones but scientists said acoustic neuroma would be the most likely candidate.
"The results of our study suggest there is no substantial risk in the first decade after starting use," said Anthony Swerdlow of the British Institute of Cancer Research but emphasized he could not rule out higher risk over a longer period.
The study, said to be the largest to date, was conducted with 678 people with acoustic neuroma and 3,553 people who did not have the tumor. Participants were asked about their cell phone use, including length and frequency of calls, makes and models of phones used, and extent of hands-free use. Subjects also were asked to detail other factors that might affect their risk of acoustic neuroma.
The study found no relation between the risk of acoustic neuroma and the number of years for which mobile phones had been used or the total number of calls placed. It also found no difference between results when testing analog or digital phone use.
Previous independent studies have found that mobile phone radiation may have some effect on the human body, such as heating up the brain and causing headaches and nausea. But the cell phone industry argues there is no conclusive evidence that electromagnetic radiation causes harm.
One skeptic, Alisdair Philips of the British group Powerwatch, said it was too early for any definitive conclusions to be drawn from the study.
"It is only one type of brain cancer and we know that brain cancer is actually on the increase -- a very steady increase -- and we don't know why," he said.
The British government has adopted a "precautionary approach" to the possible adverse effects of mobile phones, despite their own researchers finding no direct link between use and ill-health. The Department of Health advises youngsters to keep mobile calls short and send text messages where possible.
About 780 million mobile phones are expected to be sold this year, they are used by nearly 2 billion people around the world. The institute's analysis pooled studies conducted in Britain, Denmark, Finland, Norway and Sweden -- all countries where mobile phones were introduced early and have been in widespread use for a decade or more.