Would you stick your head in a microwave oven? No? Then you also shouldn’t be using your cell phone without protection — or, for that matter, using the internet over a wireless network. Actually, while we’re on the subject, you probably shouldn’t sit too close to your television either. In fact, staying inside your house wrapped in tin foil might be the best option — that is, if the claims of many anti-radiation activists are to be believed.
Microwave radiation has had a bad name ever since investigative journalist Paul Brodeur wrote about the dangers of “what you can’t see” for the New Yorker in the 1970s. But the movement to restrict microwave radiation has been gathering more steam in recent years. Citing uncertainty surrounding the carcinogenic effects of microwaves, several schools in France, Canada and Israel have recently restricted the use of WiFi to protect children in classrooms. And earlier this year, a wave of articles in the media about a (scientifically unsupported) condition called “electromagnetic hypersensitivity” sparked a renewed public interest in the radiation debate here in the US.
But what is microwave radiation anyway? And does it really pose as much of a health risk as “safe technology” proponents and media organizations would have us believe?
What is Microwave Radiation?
Microwave radiation refers to the energy emitted by electromagnetic waves with wavelengths anywhere between one millimeter and one meter. Microwaves are “micro” only in relation to radio waves: they have a shorter wavelength and therefore higher frequency than radio waves, but a much longer wavelength and lower frequency than many other types of wave in the electromagnetic spectrum, including gamma rays, x-rays, ultraviolet and visible light.
Microwaves are, as skeptics will remind you, all around us. They are used in many home appliances, including wireless internet routers, mobile phones, baby monitors, televisions and, of course, microwave ovens. They are also used to communicate with satellites, forecast the weather and detect motion in alarm systems and automatic door sensors. In fact, the world would be a very different place without the technological luxuries afforded by using microwaves.
An important point to bear in mind when considering potential health risks is that microwave frequency radiation is non-ionizing. Like radio waves and visible light, it does not have enough energy even at high intensities to break the chemical bonds that hold atoms together.
By contrast, ionizing radiation, such as gamma and x-ray radiation, does have enough energy break the bonds between atoms. This bond-breaking property can, in some conditions, cause serious damage to living organisms either by killing cells or by causing DNA mutations, which can later lead to the development of cancer. (It can also be harnessed by medics to target specific cells in the body during radiotherapy.)
The intensity of your exposure to any form of radiation depends on your distance from the radiation source. So it’s true that you would likely experience a higher intensity of microwave radiation standing next to a cell phone tower than you would while sitting in your living room. But how that radiation would affect your body is a subject of much dispute. While high intensity ionizing radiation is widely acknowledged to increase a person’s risk of developing cancer, the debate surrounding non-ionizing radiation appears, on the surface, to be far less clear-cut.
Does Microwave Radiation Pose a Health Risk?
Although microwave radiation is non-ionizing, relatively low-frequency and usually considered fairly harmless, claims that it has adverse health effects are remarkably easy to come by.
The claims vary widely in their scope, covering everything from new evidence that mobile phones cause cancer, to arguments that WiFi routers disrupt the normal development of the brain, to reports on the heightened occurrence of leukemia among people living underneath power lines.
One major source of confusion is an oft-cited monograph published in 2011 by the International Association for Research on Cancer, which included a classification of some low-frequency, non-ionizing radiation as a class 2B carcinogen. Officially, this classification defines microwaves as ‘”possibly carcinogenic to humans” on the basis of scientific research. But although this classification was quickly seized upon by activist organizations around the world as hard evidence to feed their fears, it deserves a little more explanation.
The association’s “possibly carcinogenic” category is assigned to any agent which has “inadequate evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals, together with supporting evidence from mechanistic and other relevant data.” In other words, the available evidence may be unreliable due to small sample sizes, poor experimental design or inherent biases. (Incidentally, group 2B also lists coffee, gasoline, derivatives of coconut oil and pickled vegetables as possible carcinogens.)
As for the studies alleging to provide such evidence, a closer look at the literature reveals that research articles claiming a link between microwave radiation and cancer are frequently controversial, heavily criticized and rejected by the majority of scientists in the field. Even when considering the use of cell phones, one of the most studied microwave devices, the World Health Organization concluded again last year that, “to date, no adverse health effects have been established.”
But what about other ways that microwaves could cause harm aside from an increased risk of cancer? Can microwave radiation be dangerous even if it isn’t ionizing? Well, yes, potentially. And this is where sticking your head in a microwave oven comes in.
Microwave ovens cook food by blasting it with high intensity radiation. Water molecules in the food absorb energy from the microwaves and begin to vibrate, dispersing this energy to other molecules in the form of heat. Far from cooking food “from the inside out”, microwaves can penetrate only an inch or so deep in most of the materials you’re likely to cook in your oven. In items that exceed this depth, you may find that the center is colder than the rest of the food, which is why most instruction guidelines advise you to “leave food to stand” in order to give the heat time to disperse more evenly.
Coming into contact with this radiation would entail the same sort of damage caused by any high power heat source: a thermal burn. Sticking your head in a microwave oven would therefore indeed be a dangerous enterprise — if you could get around the safety mechanisms preventing the oven operating with the door open, of course.
Does that mean you could get a thermal burn from standing too close to your WiFi router? Unlikely. Another crucial, often overlooked factor to consider is the power of the radiation source in question. Although WiFi routers generally use the same sort of frequencies as microwave ovens, they have a much lower power (about 1 Watt, as opposed to the 500-2000 Watts used by an oven). Routers use this tiny power to emit radiation in every direction, instead of focusing on the small cube of air in which you have placed a pop tart.
The absurdity of ignoring these details when determining whether or not an agent is dangerous is nicely captured by Jack Schofield in his technology column in the Guardian: “It’s also possible to use a high-pressure water jet to cut through steel,” he writes, “but that doesn’t mean you’ll die from taking a bath or standing under a fountain.”
Even a phone held close to your head doesn’t have enough energy to penetrate the skin more than a few millimeters. In fact, according to the Federal Communications Commission, the usual exposure of humans to radiation outside of their microwave ovens is “far below levels necessary to produce significant heating and increased body temperature.”
Why Are People Still Debating the Health Effects of Microwave Radiation?
Given the apparent safety of the microwave radiation levels experienced by most people in the US, it is perhaps surprising that there is still so much public suspicion. But the debate persists in the media, in schools and universities, at local council meetings and, naturally, all over the internet.
One of the reasons that the debate is particularly hard to resolve is because the subject matter is so technical. Most radiation is invisible, and to those of us without a solid understanding of the underlying physics, this invisibility, combined with unfamiliar terms such as “non-ionizing” and “electromagnetic,” can make microwaves seem a little mysterious — and, to some, more than a little threatening.
There are also undoubtedly some people who have an interest in prolonging the debate. After all, would a customer who felt safe around modern technology really consider buying a “wave shield” to reduce the risk of using her mobile phone?
But even in the absence of any further studies purporting to show a link between cancer and microwave radiation, the scientific impossibility of proving the opposite — that is, proving the absence of any danger — is likely to be enough to keep some people convinced of the risk. Mobile phones and wireless networks are still relatively recent inventions. Like the long-debunked myth that some vaccinations increase a child’s risk of developing autism, the theory that microwave radiation causes cancer may take some time to disappear from the public consciousness.
Still, if you remain unconvinced and would prefer to be safe rather than sorry, aluminum foil is a fashionable and inexpensive option to shield you and your home from several forms of radiation. Its reflective surface does a good job of blocking electromagnetic waves and also acts as an effective heat insulator. Just don’t put it in the microwave oven.