RF Exposure and You
There has been a lot of buzz in recent years about the possibility that cell phones could be hazardous to our health because of the radiation they emit in close proximity to our bodies. The recent announcement by the World Health Organization (WHO) that mobile devices are possibly carcinogenic has brought this issue to the fore once again. Since many of us web marketers and IT people use mobile devices daily, I thought it would be worthwhile to put on my radio-geek hat and offer some thoughts on this topic.
It’s important to keep in mind a couple different quotes from the USA Today article I linked to above:
Cancer researcher Peter Shields of Georgetown University Medical Center cites three categories of risk: possible, probable and known. Cellphone radiation falls under “possible.” “This is nothing like asbestos or smoking, which causes cancer in one of 10 people who smoke cigarettes.”
The WHO is talking about a possible risk, not a sure-fire thing.
Donald Berry of the MD Anderson Cancer Center in Houston notes that there has been no increase in U.S. brain cancer rates despite huge growth in cellphone use. The notion that cellphones cause brain cancer is “just an urban myth that keeps coming up,” Berry says. “The panel somehow decided that there is maybe something here that’s possibly carcinogenic, which ranks with everything else in the world.”
It seems to me if there were a high risk here, there would be some correlation between increased mobile use and cancer. There doesn’t appear to be such a correlation.
As I wrote in my article about mobile device antennas last year, the FCC very strictly regulates radio frequency (RF) energy exposure limits because RF is absorbed by the body, especially in the microwave frequencies used by mobile devices.
A little background
Microwave ovens have been commonly available since the 1970s. One of the first brands was the Amana Radarange; so called because it used RF energy in the same frequency bands as radars used at the time. Amana, in those days, was a subsidiary of Ratheon, a manufacturer of radars and radar parts. Radars and microwave ovens use magnetrons, high-powered microwave transmitters.
Microwave RF energy causes molecules of certain substances to vibrate rapidly. The rapid vibration generates a great deal of heat. This heat is what warms up your burrito or leftover pizza when you zap it in your microwave oven. Water is especially susceptible to this vibration – and almost any organic material contains water, including you.
Some other background info
Thinking about exposure to RF energy there are four things to keep track of:
- Frequency – the items we discuss all use frequencies in the microwave part of the radio spectrum
- Power – RF energy is measured in watts. Mobile device output is typically are measured in milliwatts, thousandths of a watt.
- Time – RF energy exposure can become a problem if it is for a long duration.
- Distance – The further away one is from the source of the RF, the less energy they are exposed to.
There’s nothing to be done about the frequencies. Each device and the transmission modes they use are regulated by the FCC (or other government agency). Power levels are also set by the FCC. They are not usually adjustable by the end user. So, there’s nothing much we can do about that, either. Power levels over time are measured as the Specific Absorption Rate (SAR). You can read about FCC guidelines on their web site.
The SAR of mobile phones, Bluetooth headsets, Wi-Fi hotspots, Mi-Fi devices, Wi-Fi-enabled laptops, tablet devices, wireless game controllers and such can be found on the FCC web site as well. The power output of these devices is low enough that they pose little risk to users’ health. Still, keeping in mind that most things are OK in moderation, it’s not a bad idea to moderate your exposure to RF energy.
What You Can Do
That leaves us with distance and time as the two things we can change to limit our exposure. While the health risks of low-level RF exposure is small, here are some ideas on how you can limit it and further reduce that risk:
- Don’t wear your mobile device on your person all the time. When you are at home or at the office, set it more-than-arms-length away when you’re not actually using it.
- If you’re going to talk on the phone for an extended period of time, use a Bluetooth headset. While these still use RF to operate, the power output is much lower, still, than your phone. For even less RF exposure, use a wired headset.
- Put your home Wi-Fi router up and out of the way of people.
- If you can, turn the Wi-Fi feature off on your notebook and plug it into a router with a cable. Of course, if you’re plugging into a router which also does Wi-Fi, use a longer cable.
- If you can, turn your wireless devices off when they’re not in use.
- Even though your microwave oven is shielded to avoid microwave “leakage,” there is still a possibility that some could “escape.” When running your microwave, don’t stand directly in front of it.
What say you? How do you feel about the announcement by WHO? Do you think there are significant risks to mobile device use or is this much ado about nothing? Please feel free to share in the comments.