In the 21st Century, we live in a sea of radio waves. No one wants to think that this might have consequences for our health – there are enough things to worry about that are more within our power to change. We get plenty of encouragement not to think about the subject from the news media which, come to think of it, are not so easily distinguished from the telecomm companies. The danger is real, if not so easy to quantify, and common sense suggests we might mitigate the largest sources of risk with minimal inconvenience.
It was twelve years ago that a neighbor asked me if she should worry about exposing her teenage children to cell phone radiation. I put on my physicist’s hat and patiently explained to her the difference between ionizing and non-ionizing radiation. Radiation comes in little quantum packets, and the type of radiation corresponds to how much energy is in each packet. UV, X-rays, gamma rays and cosmic rays all pack enough energy in each photon that they can damage the complex and delicate chemicals, including DNA, on which our life depends. Radio waves are low-energy radiation. Each single packet lacks the punch to break a chemical bond, and so the only way they can affect our chemistry is if many of them act together. This (I explained) is called “heating”. Unless a radio signal is strong enough to change our temperature, then it can’t be doing any damage.
I was not alone in accepting this theoretical “proof” that non-ionizing radation can’t hurt us. Throughout the 20th Century, as radio technology was being developed with wider applications in more bands of the spectrum, scientists and regulators universally assumed it was (biologically) a benign technology.
No one, in good conscience, can think that way any more.
Studies of health hazards linked to microwaves have left the threshold of plausible deniability far behind, and it is only through an extensive program of censorship and scientific disinformation that the subject has been kept from the mainstream of public discourse. Devra Davis has worked tirelessly to advocate and educate on the connection between cell phone use and brain cancer.
So far, there has been no public health catastrophe, but (as Davis explains), there is a time lag of up to ten years before cancer develops, and the rapid rise in the use of cell phones may take a much larger toll in the coming decade.
Three important and very different questions arise:
What can we learn about fundamental cell science from the fact that biological systems are sensitive to radio frequency?
What practical measures can we take in our daily lives to mitigate the risk of radio waves?
What policies and regulations should government be promoting to guide broadcasters and manufacturers of consumer devices toward safer technologies?
I’ll say a few words about the first two, and refer you to the EMR Policy Institute for the third.
What can we learn about biology?
Strong interactions between radio frequency (RF) radiation and living cells is surprising to a physicist, but perhaps not utterly mysterious. In my opinion, the most plausible theories involve resonance.
When you tune your radio to a particular station, you are programing the receiver to focus on one particular frequency, corresponding to an exact amount of energy in each quantum packet. A large number of packets confined to a particular frequency is characteristic of the way that radio communication works (including cell phones, broadcast radio, wifi and bluetooth, etc). Back in the 1970s and 80s, a German-British physicist named Herbert Fröhlich wrote some far-sighted theoretical papers about ways in which biomolecules might respond to RF radiation that happened to resonate with their vibrational frequencies. When the frequency of a radio wave corresponds to a vibrational mode for a molecule, the interaction is extra-strong, and it may be that the molecule is induced to shake violently. There are so many biomolecules and so many different broadcast channels that resonances are bound to occur by chance. If this is indeed the reason for biological effects of RF radiation, then it may be that the radio communications that surround us could be made far safer simply by prohibitions against broadcast at certain critical frequencies.
There is a related theory that RF radiation disrupts the membranes on which cells depend to maintian their structure and separate chemical constituents in different parts.
A bit of research has been done (in Croatia and India!) to look for signs of ways that cells respond to radio waves, starting from a purely observational approach without a theory. This ought to pique the interest of every cell biologist, and new experiments should be devised to search for fundamental new mechanisms. It is a certainty that profoundly new biology remains to be discovered if this thread is pursued.
(I have difficulty explaining why this isn’t a hot field for new research, except if I think of all the monied interests that feel threatened by research in the field.) It may be that the effects are all weak and beome manifest only over longer periods of time, and this will make the phenomena a bit harder to study. But this research promises to open a whole new field of knowledge – what are we waiting for?
What can we do to protect ourselves?
So far, we know little about which frequencies might have more effect than others. Without that information, it makes sense to look just at RF power and compare exposure from different sources – especially those over which we exert some individual control.
Radio power is measured in watts, and power density in watts per square centimeter. Think of the power from a transmitter rippling outward in an expanding sphere. As you move away from a source of RF, the power gets rapidly diluted over a larger and larger sphere. Power density is computed as the output power of the transmitter divided by the area of the sphere. I assume that it is the power density that dictates the danger, and that we would be prudent to avoid the RF sources in our environment that have the highest power density.
Cell phones – The problem with cell phones arises from the facts that (1) they need to broadcast with enough power to reach a cell phone tower up to 10 miles away, and (2) people hold them close up against the heads. The transmission power of a cell phone is limited by FCC to 2 watts, and distance to the brain is less than 1 cm. So power densities inside your head can be as high as 1 watt/cm2.
Microwave ovens – I became aware that microwave ovens leak when I noticed that I couldn’t make a Skype call or watch a Youtube video from my kitchen while the microwave oven was operating. Apparently it leaked enough to interfere with the wifi in the house. Some ovens are much leakier than others. But manufacturers don’t list leakage in their specifications, and there are no government or consumer web sites where you can find a comparison. Meanwhile, there is a thriving market in microwave meters. Meters that measure just the particular frequency from ovens are inexpensive, meters that cover a broader frequency spectrum, suitable for wifi and cell phones as well, are a few hundred dollars
But in comparison to cell phone emissions, microwave ovens tend to be much smaller. The meters measure in units of 0.001 watts/cm2, which is hundreds of times smaller than what you receive from holding a cell phone next to your head.
The most practical and effective thing you can do to minimize your RF exposure is to carry a cell phone in a purse or backpack rather than in your pocket, and use a wired headset rather than hold the phone up to your ear.
Laptop computer – Typical wifi power from a laptop computer is 0.1 watt. If you work with one of these all day long and you hold it close to your body, your computer can be the second most powerful source of RF radiation in your daily life. The remedy is to turn off the wifi in your laptop and run a network cable to your network hub, rather than relying on wifi. This can be quite practical at your desk or other work area where you habitually use the computer.
WiFi – Typical home wifi systems radiate about 1 watt. If you sit right next to the unit while you work, you could be exposing your head and body to a few milliwatts/cm2, comparable to sitting next to a leaky microwave oven.
The exposure from wifi is all over your body, and constant throughout the day spent in your home or office. How does that compare to a much higher exposure concentrated at your head for a few minutes a day that you use a cell phone? This is a big question for epidemiologists, and to my knowledge there are no reported data and no one is doing such studies at present. Tentatively (based only on fuzzy theory), I would focus on the acute, high-intensity exposure and ignore the low-intensity, chronic exposure until better data becomes available.
Microwave and cell phone towers – Typically, they radiate ~300 watts. If you live right next to one, say 100 meters, then your exposure all day long is still only a few microwatts, which is 1000 times less than the exposure from sitting next to your wifi modem or your microwave oven. These, in turn, are hundreds of times smaller than the exposure from your cell phone.
Commercial radio broadcasts – The largest of these may broadcast at 50,000 watts If you happen to be within 1 km of the Empire State Building or Twin Peaks in San Francisco, you could be receiving a few microwatts/cm2 of exposure.
The bottom line
Distance trumps power. (This is the physics of the inverse-square law.) Beware the close-up sources and don’t sweat the more powerful ones far away. Carry your cell phone away from your body, and use a wired headset. The next level of protection is provided by turning off the wifi in your laptop computer. Beyond this, you might want to stay a few feet away from your microwave oven and your wifi hub. Remember that exposure from these is likely to be ~100 times smaller than from your cell phone. Don’t worry about big broadcast towers, which expose you to radiation intensities that are ~100,000 times smaller than your cell phone.
Meanwhile, there’s an urgent need to study whole-body effects and a possible frequency dependence for the biological effects of radio waves. My suspicion is that such research is being suppressed by the telecomm industry and its political influence.