The Globe and Mail

It was supposed to be the cellphone safety study that settled the scary question once and for all: Do mobile devices cause brain cancer?

But the most exhaustive investigation undertaken into the risks of getting tumours from using the phones has had inconclusive results. After studying the issue for 10 years and looking at brain cancer incidence in 13 countries, including Canada, a group of the world’s top epidemiologists has reported paradoxical findings.

First the bad news. Heavy cellphone use, defined as chatting on mobiles for more than half an hour a day over 10 years, was associated with a 40-per-cent increase in risk of a rare and often deadly brain cancer known as glioma, the same type that caused the death last year of U.S. Senator Edward Kennedy.

But the study, known as Interphone and organized the United Nations’ authoritative International Agency for Research on Cancer (IARC), found that low and moderate amounts of cellphone use seemed to offer modest protection against developing the disease.

Experts say the unusual findings, released Monday in the International Journal of Epidemiology, mean that the definitive answer on cellphone safety has yet to be given.

The question “as to whether mobile phone use increases risk for brain cancers remains open,” concluded Rodolfo Saracci of Italy’s National Research Council and Jonathan Samet, of the University of Southern California’s department of preventative medicine in a separate commentary in the journal on the results.

The observations by the two prominent epidemiologists, experts in incidence rate of diseases, suggest that the debate over cellphone safety is unlikely to go away anytime soon.

Researchers have been investigating the cancer hazard from phones because using them amounts to placing a small radio transmitter next to the head, exposing the brain and ears to microwave radiation.

The mobile communications industry maintains that there is no cause for concern because emission levels are well within government safety standards. It says the new study confirms this view.

“When you look at the study … the conclusions are that there is no overall increased risk,” says Bernard Lord, president of the Canadian Wireless Telecommunications Association, an industry trade group.

The new study was designed in the late 1990s and is only now being released, in part because the researchers weren’t quite sure what to make of the results, which were based on cellphone use among more than 5,100 people diagnosed with brain cancers from 2000 to 2005. Besides Canadians, it included people from Japan, Germany, France and Israel.

Because the study has been so long in the making, its results don’t reflect the recent explosion in mobile usage, a factor that worries some of the researchers on the project.

“I think these results are of concern because the study subjects were light users compared to today,” commented Elisabeth Cardis, the study’s lead author and a professor at the Centre for Research in Environmental Epidemiology in Barcelona.

While Dr. Cardis acknowledged the research isn’t conclusive, reducing exposure to cellphone radiation “might be a reasonable course of action until stronger conclusions can be drawn around the risks.” Dr. Cardis, a Canadian who headed IARC’s radiation group during much of the period of the study, is one of the first prominent epidemiologists to suggest caution when it comes to cellphones.

But IARC concluded that the study didn’t confirm a link to brain cancer, although the finding of increased risk among heavy users and the rapid growth in cellphone usage since the research began indicates more investigation is warranted.

“An increased risk of brain cancer is not established from the data,” said Christopher Wild, IARC’s director, in a statement “However, observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied by Interphone, particularly in young people, mean that further investigation of mobile phone use and brain cancer risk is merited.”