Whether or not there is bona fide danger in routine use of cell phones is, in fact, still unresolved. As often happens when the stakes are high and the science murky, passions and convictions tend to be running ahead of the data. There are, and have long been, scientists and citizens convinced that cell phones pose a significant threat; and there are, and have long been, counterparts convinced that we all have far more important things to worry about.
Both sides recently received another ear full of information to consider, courtesy of a study published in JAMA.
Investigators from the NIH asked 47 healthy adults to lend them their ears -- their right ears in particular. The researchers put cell phones to both ears and conducted PET scans of the brain (an imaging technique that measures metabolic activity in the form of glucose consumption) with both phones deactivated, and with the phone adjacent to the right ear activated, in random sequence. Activation of the right cell phone was in mute mode so that participants were blinded ('deafened'?) to the intervention.
The study generated three take-away messages that will likely do little to resolve the cell phone controversy any time soon. First, whole brain metabolic activity was unaffected by cell phone activation. Second, brain metabolic activity directly adjacent to an activated cell phone was significantly increased. And third, the researchers have no idea what, if any, clinical significance this has. Yes, they actually said that.
Which leads immediately to a question the rest of us need to grapple with: what do we do with this information in the mean time? For whatever it's worth, my suggestion is to accord it calm respect.
The calmness is easy to justify. A study that shows a change in glucose utilization by brain cells does not indictment of cell phones make. Brain cells routinely burn glucose for fuel, and do so faster or slower based on the work they do. REM sleep, an important indicator of sleep quality and essential to sleep's restorative powers, increases brain glucose utilization on PET scan. As, for that matter, does reading. So if increased metabolic activity in the brain is a cause to fear cell phones, I suppose it might be cause to stay away from your books and your bed as well.
But on the other hand, consider what this new study implies. Increased brain cell metabolism was unrelated to the usual work of the brain, namely thinking. In REM sleep, we are dreaming -- so the brain is at work. When we read, the brain is at work. But why should a radio-frequency-modulated electromagnetic field we don't even know is there -- and thus, can't be thinking about -- change brain function?
It does. The fields emitted by cell phones affect the cells of the brain, no thinking required. Should we be comfortable with this? Can we afford to be complacent when we, and to a greater extent our children, spend an ever increasing proportion of our lives in close proximity to fields we now know silently, insidiously change our brains? My answer is no, which is why we owe the new study some respect, particularly given its context.
We have long known radio-frequency waves penetrate our bodies, as we now know they activate brain activity, but there is no clear evidence they harm us in the process. We are left with a mechanism by which cell phones could conceivably do harm, but no real indication that they do.
The published data, based on many studies and observations in hundreds of thousands of people, remain open to interpretation. One study in the Netherlands examined the issue in over 400,000 people, and found no evidence of harm. A meta-analysis in the Journal of Clinical Oncology, however, concluded there was possible evidence of increased risk of brain tumors from extended cell phone use demonstrated in studies least subject to bias. Invariably, mention is made of the need for more research.
Cell phones have only existed since the 1970s, been in use since the 1980s, and been truly popular since the '90s. So we only have a decade, or at most two, of meaningful data to analyze. Some cancers take two decades or more to develop, so it's possible, if unlikely, that we are waiting for a slow accumulation of damage to start revealing itself. We must therefore consider that absence of evidence is not tantamount to evidence of absence.
And, of course, we don't have intervention studies, with large groups randomly assigned to use cell phones, or place their calls on placebos instead. I'm not sure how placebo phones would work, but I have a sneaking suspicion the study subjects would catch on.
History suggests the possibility of seeing risk that isn't really there. The silicone breast implant controversy persists, despite consistent and rather compelling evidence that the implants do not cause autoimmune disease. The notion that immunization causes autism won't seem to die no matter how decisive the weight of evidence against any such association.
But a great deal of historical precedent cuts the other way. We have cozied up to an impressive array of genuine hazards with a misguided sense of security, including the radioactive radium that made watch faces glow in the dark but caused cancer; mercury used in hat-making that caused neurological disease; lead used in cookware that damaged nerve cells; asbestos in buildings and clothes that is still causing asbestosis and mesothelioma; thalidomide, a sedative that caused birth defects; Vioxx easing joint pain while causing heart attacks; and the list goes on.
If cell phones cause harm, the risk appears to be small, and the harm long delayed. But even one extra case of cancer in 100,000 people after 10 years of use would eventually turn into a huge and unacceptable public health toll. Such a hazard would be very hard to see at this point.
Let's turn to the practical. I will keep using my cell phone, and my kids will keep using theirs. I do think any risks are small. But I cannot be sure the risk is nil, and I am not wildly enthusiastic about the cells in my kids' brains being activated by anything other than thinking. So I will encourage my children to use their phones for good reason, rather than make them a permanent extension of their heads. There is certainly no cause for panic, but I'm not a fan of presumptive complacency.
The 19th century philosopher George Santayana wisely noted that those who do not learn from the follies of history are doomed to repeat them. The folly of rushing into hazards of our own devising with a false sense of security has filled many pages of our history books. Whether cell phone use will prove to be another example is far from certain. But when precedent calls, it is at least prudent to lend our ears.
Follow David Katz, M.D. on Twitter: www.twitter.com/DrDavidKatz