Cellphone Users Face Risk

People who have used cellphones for at least 10 years may have an increased risk of developing a rare brain tumor, according to a study published in the international journal Epidemiology. Researchers at the Institute of Environmental Medicine at the Karolinska Institute in Stockholm, Sweden, found almost a fourfold increase of the tumors — known as acoustic neuromas — on the side of the head where the phone was held most often.

The work was done as part of the World Health Organization's cellphone research agenda, and experts in the field said it must be taken seriously and is likely to rekindle consumer worries about the risks of using the phones.

"The Karolinska researchers are respected around the world, and this study will force health agencies to take a fresh look at mobile-phone risks," said Louis Slesin, publisher of Microwave News, who has been covering the industry since its early days. "This study should put an end to the industry's call to stop mobile-phone health research."

At least one past study conducted for the cellphone industry also had suggested a link between the phones and this type of tumor. But cellphone-industry officials yesterday said no conclusions can be drawn from the Swedish research.

The study, involving 150 acoustic-neuroma patients and 600 healthy people, is one of at least six studies that have investigated possible links between cellphone use and acoustic neuromas. Most had fewer long-term users than the Karolinska study.

Acoustic neuromas are slow-growing, noncancerous tumors that develop on a nerve linking the brain and the inner ear. The most common first symptom is hearing loss, but the tumor as it grows can push against brain tissue. If not treated, it can be life-threatening. Such tumors occur in about one person per 100,000 in the general population.

To conduct the three-year study, researchers interviewed people who had developed the tumors — asking about their cellphone use, how many phones they had used, the make and model, duration of calls, whether they used a hands-free set and on which side of the head they held the phone.

Researchers said they found no association between the tumors and the amount of use measured in hours or cumulative number of calls, but rather on the length of time those in the study had been regular users of cellphones. Regular use was defined as an average of at least once a week during six months or more.

Anders Ahlbom, director of the Institute of Environmental Medicine, said in a phone interview that the data are statistically significant, but follow-up studies are needed. He said the mechanism by which cellphone radiation might cause tumors is unknown.