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Long-Term Cell Phone Use May Increase Risk of Brain Tumors
An analysis of 11 published studies on cell phone use concludes that long-term cell phone use approximately doubles the risk of developing two types of brain tumor.
Most studies to date have found no association between cell phone use and head tumors. But many of these studies were short-term in nature. The 11 studies analyzed here all looked at cell phone use over a period of ten years or longer.
Cell phones emit low-energy radiation (microwaves). Some of this radiation passes through the skull and into the brain. Penetration can be over two inches in adults and further in children. It is not currently known if this radiation is dangerous or harmless. Though it seems as if cell phones have been around forever, they haven't been in use long enough to answer this question. This particular analysis finds the radiation to be dangerous.
The authors of the analysis make several recommendations on how concerned users can lower their radiation exposure. Aside from the obvious ones about limiting cell phone use, the suggestions include using an air tube headset (not a wired headset) and not making calls when the signal strength is one bar or less.
Radiation exposure decreases according to the inverse square of the source's distance. That is, moving the phone three times further from the head means one-ninth the radiation exposure.
The 11 studies in question belong to two sets: one funded by the cell phone industry (the Interphone studies), one conducted by independent researchers (the Hardell Studies). The Interphone studies found no increase in brain tumors with increased cell phone usage. The Hardell studies found that more cell phone usage, higher radiation exposure, more years of usage and lower age of the user all increased the risk of a brain tumor.
Combined statistical analysis of all 11 studies found that using a cell phone for 10 years approximately doubled the risk for developing a glioma or acoustic neuroma in the same side of the head as the phone was normally used.
Gliomas are the most common malignancy of the central nervous system in adults and are rarely curable. Acoustic neuromas are benign tumors.
The authors of the analysis criticize several aspects of the industry-funded Interphone studies. These studies compared regular cell phone users to non-users and defined a regular cell phone user as anyone who used a cell phone more than once a week for over six months, a rather minimalistic definition. They also selected their subjects mainly from metropolitan areas (cell phone use in rural areas generally requires higher power and emits greater radiation). Both of these design factors could have caused underestimation of the actual risk to cell phone users.
Cell phones, power lines and satellite dishes all emit low-level radiation. It is simply not known yet whether these emissions have undesirable health effects or not. For people who want to lower their radiation exposure from cell phones, the authors of the analysis offer 13 separate recommendations on how to do so:
Risk of Brain Tumors From Wireless Phone Use appears in the November/December 2010 issue of Journal of Computer Assisted Tomography and is freely available.
February 4, 2011
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