If you keep up on the news, you may have seen that a study was partially released last week which suggests a possible correlation between tumors in rodents and exposure to microwaves. The big worry is that under some circumstances the type of microwaves emitted by cell phones can interact with animal tissue, and this interaction can result in serious health problems—including cancers of the central nervous system. There are few diagnoses more terrifying than brain cancer and given how many of us use cell phones, it’s understandable that even the remote possibility of a link between the two generates intense anxiety.
For years now, researchers all over the world have looked for any empirical correlation between phones and cancer. Databases have been examined, cancer clusters evaluated, and lab animals blasted with radiation of all sorts from birth to death. This is from the American Cancer Society website and reflects those findings to date:
Food and Drug Administration (FDA): “The majority of studies published have failed to show an association between exposure to radio frequency from a cell phone and health problems.”
Federal Communications Commission (FCC): “There is no scientific evidence that proves that wireless phone usage can lead to cancer or a variety of other problems, including headaches, dizziness or memory loss. However, organizations in the United States and overseas are sponsoring research ...”
Centers for Disease Control and Prevention (CDC): “At this time we do not have the science to link health problems to cell phone use. Scientific studies are underway to determine whether cell phone use may cause health effects.”
There’s a lot here to discuss and experts from the field are heartily encouraged to chime in. We’ll get to the study in question below the fold—just keep in mind that this issue can kick up a surprising amount of dust and flames.
The term radiation has become synonymous with all kinds of monstrous peril, no thanks to movies about post-apocalyptic mutants. It is true that some high energy forms of radiation can cause changes in DNA which, in one in a zillion cases, can then go on and be expressed in offspring in some immediately visible way. One way to change DNA directly like this is if tiny, energetic particles/waves rip through the delicate material like a bullet rips through a vital organ. It’s just a matter of scale, really. If the radioactive onslaught turns the right genetic switches on or off and leaves a few cells otherwise healthy enough to reproduce, they may start reproducing without limit—and that’s one way a malignant tumor is born.
But the radiation emitted by common household objects like microwave ovens or cell phones is not in that class. It’s technically accurate to call it radiation, but it’s almost pejorative in this case. The same could be said of the color yellow. Physicists call it non-ionizing radiation because it’s too weak to kick particles like electrons loose from atoms, and way, way too weak to split off neutrons or protons.
Both devices use wavelengths in the microwave band of the electromagnetic spectrum, way below the visible part. The question is, can microwaves cause damage indirectly? More to the point, microwave ovens can sure as hell cause tissue damage, so why couldn’t another device that also emits them follow suit?
Your average household microwave oven uses a narrow wavelength and frequency band chosen for its effect on dipole molecules. Through a fascinating interaction, molecules like H2O can pick up a portion of the energy at that frequency and flip-flop around in the process. Well, flip-flopping means movement, that movement agitates any adjacent molecules, on the molecular scale movement equals heat, and presto—your soup heats right up!
Cell phones operate in a band well away from that one.
But there’s another big difference between cell phones and ovens besides frequency: power! The signals emitted by typical cell phones are measured in milli-watts—one or two watts at most, and then only rarely.
Ovens, on the other hand, come ready made in the 500 to 1,000 watt range. That’s on the order of a 1,000 to 10,000 times more powerful than a cell phone. To put it in visceral terms, imagine the difference on your eyeballs between staring into a nice roaring fire and staring at the sun.
For these reasons and other, even more esoteric ones, it’s unlikely in the extreme that microwaves emitted by phones can directly damage DNA.
Of course living systems are incredibly complex things, and there’s always the chance of some sort of indirect, secondary chain reaction. Ironically, we now know that some cancers may be caused by the process of healing itself: When adult stem cells swing into action to heal damage, one of those cells could make a break for the bad and that’s a plausible, if purely hypothetical, pathway to a tumor. If it could be shown that any internal damage occurs in nerve tissue, from any source, even at low levels the user would be unaware of, that could be worth investigating.
But there are at least two big ways we think phenomena like this should have shown up years ago, regardless of how the pathology might work. The first is in data sets. The National Institutes of Health and other organizations maintain vast databases of health-related attributes. They are among the most robust in all of science. When even a smallish cancer cluster shows up in an obscure region, sooner or later it tends to stand out. The world has been bathed in radio and TV signals for the better part of a century and cell phones have been in wide use for more than 20 years. How an unambiguous link would “hide” in all that data over all those years is difficult to fathom. On the face of it, either some other factor[s] would have to be masking it somehow, or it would have to be rare indeed.
The other way is by direct study. Researchers can examine active and past cancer patients and compare them by all kinds of variables to other populations like geography and family history. They can check them directly for known risk factors of the genetic or environmental kinds and assess correlations. In an even more direct approach, researchers can create the suspect conditions and look for correlations: Take a population of rats or mice (or any other unfortunate animal), split them up into various groups, subject some to microwaves at whatever wavelengths are of interest, and look for differences in cancer rates.
When we say most studies to date have found no evidence of a link, these are the kinds of studies we’re referring to. It was the latter, direct kind of study that was recently released:
About 2 to 3 percent of the male rats in many of the dose groups developed malignant glioma, a form of brain cancer, while none in the control group did. Up to 3 percent of the rats in the different exposure groups developed precancerous brain lesions, while again none in the control group did.
The authors said the trend toward higher risk was statistically significant for the CDMA radiation but not for the GSM. The evidence of risk of cardiac tumors was somewhat stronger. In the groups given the highest dosage, 5 to 7 percent of the male rats developed schwannomas, compared to zero in the control group.
The science side of me accepts the current consensus that there is no known link between cell phone emissions and nerve tissue cancers. But I must confess some personal emotional bias: There are several things that jumped out here, things I would like to see addressed and laid to rest.
First up, neurons don’t reproduce. That’s one reason head and spinal cord injuries can be so serious. Among the few upsides of that is they don’t cause diseases, like cancer, defined by abnormal reproduction. But there are supporting cells in nerve tissue, especially the neuroglia, that do reproduce and are notorious for causing tumors. The new study refers to two kinds, gliomas, brain tumors caused by glial cells, and schwannomas, tumors from a type of glial cell that serves peripheral nerve tissue outside of the brain. Not sure why, but that finding seemed a little eerie.
Secondly, why the delta between CDMA and GSM? CDMA (or Code Division Multiple Access) and GSM (or Global System for Mobiles) are widely used, competing encoding formats for wireless devices. The fact that one caused tumors above the expected background rate and one did not suggests at least a methodology error, and possibly something more profound.
Lastly, the tumors only occurred in male rats. That’s so weird it practically begs for some kind of error sneaking into the study, but what it would be is hard to say without knowing more.
To repeat: There have been multiple studies over many years and so far no consensus link has been found between cell phones and cancer. To put this study in that context, imagine you had a dozen well-calibrated thermometers all reading 50 degrees on the nose and one lone thermometer that read below freezing. It’s possible something is wrong with the dozen reading high. But that one low thermometer would be far and away your first suspect, right?
In much the same way, this new study must be viewed with a big dose of healthy skepticism. For now, it is an outlier. Let’s wait and see if any of these results can be reproduced or nullified before we hit the panic button.