Sunday Forum: Stop freaking out about cell phones!
Physicist ERIC SWANSON explains why it's virtually impossible for cell phones to cause cancer
August 3, 2008 8:00 AM
About 3 billion people use cell phones on a regular basis. That makes 8 billion pounds of brain matter being subjected to cell phone radiation every day in what amounts to a massive experiment on the relationship between radiation exposure and cancer. This is serious stuff; if cell phones cause cancer a lot of people are going to be sick, and a worldwide multibillion-dollar industry is going to collapse.
Many people seem to have made up their minds already. Dr. Ronald Herberman, head of the UPMC Cancer Center and the University of Pittsburgh Cancer Institute, recently issued a highly publicized internal memorandum warning staff members of the health risks of cell phones. He has also announced plans to conduct a large-scale study of the issue.
But before you flush your cell phone down the toilet (again) and wrap your head in tin foil, let's look at how well these claims are supported.
Dr. Herberman says, "We shouldn't wait until definitive information comes out. By then, we might have a virtual epidemic on our hands."
Eric Swanson is an associate professor of nuclear physics at the University of Pittsburgh, a member of the American Physics Society Forum on Physics and Society and a member of the Union of Concerned Scientists (firstname.lastname@example.org). He does not use a cell phone because he finds them annoying.
Well, that's not very convincing: We might also have an epidemic of pod-popping aliens on our hands, too, but no one is too worried about that. Can we do better?
Dr. Herberman mentions that the Toronto Department of Public Health also has issued an advisory. Some quick Googling reveals that the Toronto advisory was issued by an anthropologist. An anthropologist? Where are the detailed studies by experts?
The Post-Gazette reported that Dr. Herberman's warning had been encouraged by Dr. Devra Lee Davis, director of the University of Pittsburgh's Center for Environmental Oncology. Now we're getting somewhere! An expert like Dr. Davis surely will straighten out this mess: "The question is do you want to play Russian roulette with your brain? I don't know that cell phones are dangerous. But I don't know that they are safe."
Come again? Saying that you "don't know that they are safe" is not the same as saying they are unsafe. After all, I also can't prove that cell phones do not permit some users to fly. That is not the same as saying that cell phones enable flight. No self-respecting scientist should use the absence of a positive to prove a negative.
Going further afield, the British newspaper The Independent reported that Dr. Vini Khurana states that mobile phones could kill more people than smoking. More Googling reveals that Dr. Khurana is a neurosurgeon. OK, he's a brain surgeon, but does that make him qualified to do large-scale statistical studies on cancer?
It looks like cell phone alarmists either refer to each other or to dubious studies to support their claims.
How well do their claims stand up to science and common sense?
First we need to clarify that the radiation we are talking about is electromagnetic radiation. Other examples are X-rays, radio waves, microwaves and visible light.
Electromagnetic radiation interacts with matter by bouncing off of charged particles, mostly electrons in the outer orbits of atoms and molecules. Light is absorbed by a brick because the brick is dense with electrons that love to interact with visible light. Glass is transparent because the electrons that help make it up do not play well with visible light.
Can electromagnetic radiation cause cancer? Yes! This is the reason your dental assistant leaves the room when she X-rays your sore tooth. Lead does a good job of absorbing X-rays, which is why the apron that covers your delicate bits is heavy.
Ultraviolet radiation is also dangerous because it can cause skin cancer. This is the UVA and UVB radiation that sun screen is designed to protect us from.
What about visible light? You've probably seen truck drivers with tan left arms or beach-goers with raccoon eyes because they have been wearing sunglasses all day. The exposed skin is tan (and susceptible to cancer) because it has been exposed to ultraviolet radiation; the skin behind glass remains paler because glass absorbs ultraviolet radiation while letting visible light pass. In other words, visible light does not tan skin or cause cancer.
Why are X-rays and UV radiation dangerous while visible light is not? The answer has to do with the nature of light and of our DNA.
Cancer happens when cells start reproducing in an uncontrolled fashion. Since cell reproduction is controlled by DNA we might conclude that X-rays and UV rays damage DNA molecules in some way. In fact this is exactly what happens.
X-rays and UV rays carry enough energy that they can physically rearrange DNA structure (and that ain't good!). Visible light is not dangerous because it does not have enough energy to damage DNA. The amount of light you are exposed to does not make a difference; it is the energy level, not the amount that matters. That's why your skin can happily spend countless hours, day after day, exposed to artificial lighting (which has very little UV).
What about cell phones? They typically broadcast between 800 Mhz and 2.1 GHz, which corresponds to an energy that is one million times less than visible light.
We know the human body has evolved to not get cancerous when exposed to visible light. What are the odds that it will develop cancer when it is exposed to much less energetic radiation? Not high: It's like saying a Mack truck can easily handle collisions with Volkswagens while fearing the truck will fall to pieces if a Frisbee hits it.
The only effect of such low-energy radiation is a tiny amount of heating of the ear and brain matter -- about one one-thousandth as much as the brain heating caused by wearing a hat. If cell phones cause cancer, 1.3 million Mainers need to burn their toques.
The nature of light and of our bodies suggest that cell phone radiation cannot cause cancer, no matter how much is present. Similarly, radio waves, TV transmissions, microwaves and the radiation from power lines are all too feeble to cause DNA damage, and, hence, cancer.