Back in the technological dark ages—1993, to be exact—Kevin Nealon reported the following satirical news item on Saturday Night Live: “A recent study indicates that cellular phone users may be more likely to develop brain tumors. The problem has gotten very little public attention, however, since most people don’t care if people who use cellular phones die.”
That was when cell phones were strictly for wealthy people, many of whom liked to flaunt their wealth by talking loudly on the phone in public. Now just about everyone can talk loudly on the phone in public, and as cell phone use has grown, so have concerns about the possible health effects.
Recently, an Expert Committee from the Norwegian Institute of Public Health provided some reassuring news in a 200-page report on the effects of exposure to low-level radiofrequency electromagnetic fields, specifically from cell phones. After careful examination of numerous cohort, case-control, and cancer incidence studies, the committee concluded, “Overall, the available data show no association between exposure to radiofrequency fields from a mobile phone and fast-growing tumours, including gliomas in the brain which have a short induction period.” The committee was less certain with regard to the effects of cell phone use on slow-growing tumors, such as meningiomas and acoustic neuromas, stating that cell phones have not been in use long enough to determine whether an association exists.
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But that doesn’t settle the issue. As recently as May 2011, the World Health Organization’s International Agency for Research on Cancer convened a working group of 31 scientists from 14 countries who concluded that, given the limited evidence available, a link between cell phone use and brain tumors couldn’t be ruled out. They gave the risk a 2B classification, meaning that they consider cell phone use “possibly carcinogenic to humans.”
Recent research is equally contradictory. Evidence of the benign effect of cell phone use came from the INTERPHONE case-control study, in which researchers interviewed 2,708 individuals with glioma, 2,409 with meningioma, and similar numbers of matched controls from 13 countries. Strangely, having ever been a regular cell phone user actually reduced the risk for either cancer, whereas being in the top 10% of cell phone users increased the risk for both. The investigators acknowledged that recall bias or methodological limitations probably skewed these results. A few participants reported talking on a cell phone for more than 12 hours a day, which sounds implausible, except to the parents of teenagers.
On the other hand, a pooled analysis of data from 1,251 patients and 2,438 matched controls conducted in Sweden found that the risk of malignant brain tumors increased with the cumulative hours of use and time since first use of cell or cordless phones. In the subgroup who had been using wireless phones for >10 years, the risk of astrocytoma was 2.7 times higher for cell phone users and 1.8 times higher for cordless phone users. First use of either device before the age of 20 years further increased the risk. As with the INTERPHONE study, recall bias may have distorted the results.
Given the widespread use of cell phones, if they caused brain tumors, it would be reasonable to expect an overall increase in brain tumor incidence—but that hasn’t been the case. In a US study, the incidence of glioma remained unchanged during the period 1992 to 2008. Had tumor incidence reflected the risks calculated in the Swedish study, a 40% increase in glioma incidence would have been expected. In a similar study conducted in the Nordic countries, a slight increase in glioma incidence for the years 1979 to 2008 was noted (0.4% for men and 0.3% for women), but no clear trend suggesting that glioma incidence is linked with cell phone use could be identified.
Further reassuring evidence came from a Danish cohort study, which found no link between risk of glioma or tumor location and years of having a cell phone account.
Thus, although the question hasn’t been definitively settled, the evidence that’s available seems to suggest that you should feel pretty safe when talking on a cell phone. Just not too loudly in public, okay?
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