Simple answer: we still don't know.
The results from the INTERPHONE study were published in the May issue of the International Journal of Epidemiology. This is the world's largest study on cell phone use and brain tumors. The INTERPHONE study's main goal was "to determine whether mobile phone use increases the risk of brain tumors and, specifically, whether radiofrequency energy emitted by mobile phones is tumorigenic."
An additional question addressed was: "do mobile phones increase the risk of brain tumors within the first 10-15 years of use?"
Unfortunately, due to methods, biases inherent in any epidemiology study of this magnitude, changes in mobile phone usage patterns and technology, no clear conclusions can be drawn from this study.
The International Agency for Research on Cancer (IARC) sponsored this multicenter study among 13 nations.
The INTERPHONE study is a case control study. Investigators first identified cases of meningioma and glioma between 2000 and 2004. There were 2708 glioma patients and 2409 meningioma patients studied. A "matched" control patient was identified for each tumor patient. That is a patient without a brain tumor who was of the same sex, approximately the same age, and from the same geographic region. There were 2972 matched controls for the glioma group and 2662 for the meningioma group.
During face to face interviews, all participants were questioned in detail about their past cell phone use. If the patient had died or was too ill to be interviewed, a "proxy" was interviewed.
As you can see, the results are completely dependent on a person's precise recall of past cell phone use and may not be entirely accurate.
Additional data analysis is ongoing and a large, prospective study is underway. So for now, no specific guidelines can be given regarding cell phone use and brain tumor.
- However, common sense would tell us to limit a child's usage, use speaker phone and hands free methods, use text messaging (but not while driving), and don't always listen with the same ear.