Risks to cellphone users found in higher-quality studies

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Some studies have found that using cellphones increases the risk of head and neck tumors, but others have not. A new analysis of 23 epidemiological studies, however, has found an elevated risk among the studies that were of higher scientific quality.

The report, published today in the Journal of Clinical Oncology, lumped together data from 23 epidemiological studies involving almost 38,000 people. Overall, no greater risk was found. But when the investigators analyzed eight of the studies that were conducted with the most scientific rigor, cellphone users had a 10% to 30% increased risk of tumors compared with people who rarely or never used the phones. The risk was highest among cellphone users of 10 years or more. Seven of the eight studies, however, were conducted by a single research group in Sweden.

The other 15 studies were considered to be of lower scientific rigor because the researchers conducting interviews knew which people had a history of head and neck tumors and which did not. In addition, some of the studies were funded in part by the cellphone industry.

In recent years, concerns have arisen that the radio frequency energy emitted by cellphones may be high enough to cause tumors and a variety of other health problems over time. But those risks are hotly debated.

“Larger, prospective, cohort studies, independently conducted from the mobile industry, are required to confirm the relationship between mobile phone use and tumor risk,” said Dr. Seung-Kwon Myung, the lead author of the meta-analysis, from the National Cancer Center in Goyangsi, Korea.

Many of the studies judged to be of lower quality were part of the Interphone project, research coordinated by the International Agency for Research on Cancer, an agency of the World Health Organization. Interphone is funded in part by the Mobile Manufacturers Forum and the Global System for Mobile Communication Assn.

Interphone study investigators are not influenced by the funding source, said Michael Milligan, secretary general of the Mobile Manufacturers Forum, based in Hong Kong.

“The Mobile Manufacturers Forum has provided part funding for the Interphone study that has complemented other public sources of funding – such as the European Commission and other national bodies,” Milligan said in an e-mail. “In providing funding, we have done so on terms that guarantee Interphone’s complete scientific independence.”

-- Shari Roan