From Our ArchivesMedical Authors and Editors: Barbara K. Hecht, Ph.D. and Frederick Hecht, M.D.
October 15, 2004 -- Ten or more years of mobile phone use has been found to increase the risk of a tumor called acoustic neuroma. The risk appears confined to the side of the head where the phone is usually held.
This worrisome information is in a report of a study from the Institute of Environmental Medicine at the famed Karolinska Institute in Stockholm. There is no evidence for an increased risk with less than 10 years of mobile phone use.
Radiofrequency exposure from mobile phones is concentrated to the tissues closest to the handset, which includes the auditory nerve. If this type of exposure increases tumor risk, acoustic neuroma would be a potential concern.
The Swedish Study
A total of about 150 acoustic neuroma patients and 600 healthy controls participated in a case-control study.
The risk of acoustic neuroma was found to be almost double for people who started using their analog cell phone at least 10 years before the diagnosis of their tumor.
When the side of the head on which the phone was usually held was taken into consideration, it was found that the risk of acoustic neuroma almost quadrupled on the phone side and was virtually normal on the other side.
Limitations of the
This study was retrospective and had the same significant limitations as do all retrospective studies. From the start it was already known who did or did not have an acoustic neuroma. New patients treated for acoustic neuroma in "certain parts of Sweden" were in the study.
The sample may have been biased in other ways. A nurse contacted the patients and controls and asked them if they wanted to participate and only those who said "yes" were included in the study.
Those who agreed to participate in the study then had a personal interview about their mobile phone use and other issues of importance in the study.
At the time the study was done, only analog phones had been in use for 10 years or more, so the study was confined to them. Whether the results would be similar or not after long-term use of digital (GSM) phones is not known.
Although the study has its limitations, the basic conclusion it comes to looks solid to us. It casts light not only on the danger of using an analog cell phone but also on the genesis of acoustic neuromas.
What is Happening
Acoustic neuroma is best known as the hallmark of a genetic disorder known as neurofibromatosis-2. In this disorder, a heritable mutation results in loss of function of a gene on chromosome 22. That gene normally controls the growth of Schwann cells, small sheet-like cells that grow around nerve fibers like onion skin and help support the nerve.
We would think that what is happening is that radiofrequency exposure from analog cell phones is mutating this same gene on chromosome 22, causing it to lose function and fail to control the growth of Schwann cells, and the end result is an acoustic neuroma.
Lonn S, et al: Mobile Phone Use and the Risk of Acoustic Neuroma. Epidemiology 15::653, Nov 2004