[NOTE: I'm currently in Boston attending the 2008 Industrial Physics Forum, and also writing blog posts about the various talks here. Nothing like hard work to keep one from wallowing in self-pity, right? But it means blogging will be nonexistent at the cocktail party until Thursday. So here's a handy repost from the archives as a placeholder until I get home.]
Last week, while chatting with my pal Lee — personal stylist to Jen-Luc Piquant and an occasional guest blogger here at Cocktail Party Physics — she complained about a noticeable increase in strange interference effects. For instance, she occasionally comes home to find the radio playing, courtesy of her neighbor's universal remote. And sometimes her cell phone "talks" to her computer speakers. In Lee's words, "What I want to know is, who the hell is using my cell phone to talk to the Mother Ship?"
I can commiserate, having gone through an irritating period where I temporarily lost my home WiFi signal every time I turned on the microwave. It's a fairly common problem, actually, and in my case there was an easy fix: changing the point access channels so the two radio frequency (rf) ranges didn't overlap. All this interference probably shouldn't be all that surprising, considering the growing number of wireless and remote devices scattered about the average American household: not just microwave ovens, but other WiFi access points, cordless phones, wireless video cameras, game controllers, Bluetooth devices, sometimes even bad electrical connections or fluorescent lights. No wonder rf interference is particularly problematic in population-dense areas like New York City (and specifically in Lee's densely packed neighborhood in the Bronx). The real miracle is that it doesn't happen more often.
And more devices are constantly appearing on the market: just last week, the digital design company IconNicholson announced its new three-panel Magic Mirror, an interactive technology that can be set up outside the dressing rooms of boutiques. Shoppers can see how an outfit will look on them without physically trying it on. If they're unsure about their fashion choices — and what teenager isn't? — they can send live video to their friends and receive near-real-time feedback. The company's press release describes it as "Facebook meets the mall."
Granted, the radio frequency segment of the electromagnetic spectrum covers a pretty wide range, and regulatory agencies are pretty stringent about assigning radio frequencies. Consider this list, courtesy of the most excellent site How Stuff Works:
- AM radio: 535 kHz to 1.7 MHz
- Short wave radio: 5.9 MHz to 26.1 MHz
- Citizens band radio:26.96 MHz to 27.41 MHz
- TV stations (channels 2 through 6): 54 to 88 MHz
- TV stations (channels 7 through 14): 174 to 220 MHz
- FM radio: 88 MHz to 108 MHz
You'd think that would be sufficient, but modern technology includes all kinds of small household devices, each of which also uses a specific band in the spectrum:
- Garage door openers/alarm systems: 40 MHz
- Cordless phones: 40 MHz to 50 MHz (Some newer versions are 900 MHz.)
- Baby monitors: 49 MHz
- Radio-controlled airplanes: 72 MHz
- Radio-controlled cars: 75 MHz
- Wildlife tracking collars: 215 MHz to 220 MHz
- MIR Space Station: 145 MHz to 437 MHz
- Cell phones: 824 MHz to 849 MHz
- Air traffic control radar: 960 MHz to 1,215 MHz
- Global Positioning System: 1,227 MHZ to 1,575 MHz
- Deep space radio communication: 2,290 MHz to 2300 MHz
Microwave ovens generally emit signals in the same 2.4 GHz frequency band that most WLANs employ, so occasional crossed signals are almost inevitable. That's also why the signal might sometimes be weak if too many people are using WiFi access points in the same frequency range, in the same general region, causing slower rates for Web browsing and file downloads.
(Random thought: Note that there is a 111 MHz gap between the high end of the cell phone frequency and the low end of air traffic control radar systems, yet only a 12 MHz gap between the high end of air traffic control radar and the low end of the Global Positioning System. So why do I have to turn my cell phone off during every single flight? Isn't the GPS a far greater interference risk, or am I missing some crucial point? Thoughts? Comments?)
The point is, it's clear from this ever-growing list that the technology boom is taking a bigger and bigger bite out of the radio frequency spectrum every year — or rather, new wireless devices are multiplying like rabbits, forcing us to carve out ever-smaller niches in the spectrum to make room for everything. Lee informs me that HDTV employs micro-frequencies, although I haven't been able to independently verify that — too much techie jargon to wade through on every legitimate site I perused, plus a downright dizzying array of acronyms. (Learn to speak plain English, people! Or, as Jen-Luc would say, "Il faut parler en anglais!") Clearly, we're going have to ditch some of the old technology and start all over again from scratch at some point –a huge inconvenience, but a far less daunting challenge than figuring out what to do about all that space junk (old satellites, rocket parts, etc.) floating about in space. (I try not to think too much about it; otherwise I lie awake all night worrying about satellite traffic jams in space. NASA scientists, one hopes, are on it.)
Some might argue that the problem of interference pales in comparison with unknown long-term adverse health effects that might be related to prolonged exposure to all these electromagnetic fields. "Cell phones cause cancer!" scream the fear-mongering headlines — echoes of the power line controversy in the 1980s and 1990s. There's an undeniable element of hysteria in some of this, like the case of a Welsh teacher — reported in December — who claimed to become ill whenever he taught in front of a WiFi transmitter. Most news reports failed to mention the follow-up controlled experiment, when the teacher didn't know the WiFi access point was turned off, and still reported feeling ill.
In February 2000, the Swedish National Institute for Working Life reported on a survey of 5000 cell phone users in Norway and another 12,000 in Sweden. Fully one-quarter complained they felt "warmth on or behind the ear" when using their phones, and 20% reported recurring fatigue and frequent headaches after long conversations on their cell phone. *Cue gratutious eye-rolling* Oh please. My ears get warm after prolonged lying down on a pillow, thanks to the transfer of body heat, and I have yet to hear reports that pillows might have adverse health effects. I get headaches, too, but I don't blame it on my cell phone. After all, I occasionally got headaches in the pre-cell phone era, and no one ever thought to attribute it to my AM radio. Even a rep for the Swedish National Institute admitted that they didn't specifically measure rf emissions from the cell phones, and many of the symptoms could also be traced to other factors, like plain old garden-variety stress.
It would help alleviate public hysteria if folks had a clearer understanding of the underlying science. Alas, many Websites hawking "preventive" products deliberately whip up that hysteria to get people to buy their wares. Those Websites include the New Age-y Tools for Healing, Safety Shield, those opposed to the very notion of EMFs (which makes about as much sense as opposing gravity), and — my personal favorite — the folks who market Zone-030 Protective Foil. I couldn't find a picture of their product on the Internets; in my head, I'm envisioning snazzy tinfoil hats. Then there's this new product marketed by Clarins: a spray-on mist to protect one's skin from those nasty electromagnetic waves by "coating it with an imperceptible and invigorating film" supposedly derived from "ingredients found 2000 meters deep in the ocean." According to the marketing brochure, the company's scientists exposed treated cell cultures to 900 MHz frequencies — i.e., those new cordless phones — "and found that their structures hardly changed!" (Everyone knows that using exclamation points proves you're right!!! It's SCIENTIFIC!!!)
Jen-Luc Piquant cynically points out that there is no mention of a control group experiment; chances are, exposing an untreated cell culture to the same frequency wouldn't have caused any observable changes either. Her cynicism is shared by Michael Bluck, an engineer at Imperial College, London, who rightly points out that humanity has been bathed in electromagnetic waves since the dawn of time, and that these waves are used by electronic devices precisely because they don't interact significantly with our bodies. He advised concerned readers of The Guardian (which reported on the new product) to forego buying snake-oil products like Clarin's E3p mist. If they're worried, they can "live as far away from the producers of EM waves as possible, and live with the consequences of having no friends and no life."
On the flip side, one doesn't like to blithely dismiss such concerns out of hand, especially if one has ever perused the gruesome historical archive photos of early X-ray pioneers. People used to think X-rays were harmless, too, so much so that they got "bone scans" for a lark, and even used X-ray machines in shoe stores for awhile to determine sizing. Many scientists and physicians who worked routinely with X-rays lost their hair, developed cancerous tumors, and had to have various extremities amputated before people finally realized, hey! Maybe zapping human beings with enormous amounts of X-rays isn't such a great idea! In 1904, Thomas Edison's assistant, Clarence Dally, died from prlolonged X-ray exposure. Ever the scientist, he carefully documented the burns, serial amputations and diseased lymph nodes leading up to his death. Once scientists understood the effects, they were able to develop precautionary measures, so we could reap the benefits of X-ray technology while still protecting our health.
However, the dangers of X-rays were pretty clearcut and easily observed; ditto with the high-energy gamma rays associated with nuclear bombs or power plants. Both are examples of ionizing radiation, which causes cells to mutate and sometimes die. Radio frequency energy is far, far lower, insufficient to cause mutation of biological cells. That's not to say it doesn't have biological effects: get enough rf energy focused in one place, and it can heat tissue; such an increase in body temperature can certainly cause some damage, particularly to the eyes and testes. But we're talking huge amounts of rf energy, not the incidental signals emitted by cell phones, microwaves, and other wireless devices.
And yet… and yet… with so many more rf devices popping up in population-dense regions, and people spending longer amounts of time using such devices, could there be any long-term ill effects from prolonged exposure even to the tiny rf signals being constantly emitted around us? The middle ground is to call for more research, specifically tightly controlled studies, in hopes of settling the matter once and for all. An article on the NIH Website cites several major studies showing no link between cell phones and cancer, but stops short of declaring this to be a definitive answer, because those were short-term studies.
There have been more long-term studies in the last six years indicating biological effects in animals triggered when they were bombarded with rf radiation of frequencies used by typical cell phones. A 2002 study by researchers at Washington University School of Medicine in St. Louis exposed lab rats to huge amounts of rf radiation, for hours on end, yet found no significant evidence that the exposure caused increased incidents of cancer. But there could be other adverse effects. In 2003, Leif Salford of Lund University Hospital in Sweden scattered pulses of low-level microwave radiation across the brains of rats, and found that even a single two-hour exposure can kill some brain cells. Those results await confirmation by additional studies, and even Salford cautions that his results might not apply to real-world cell phone use.
Still, the FDA and the Federal Communications Commission have taken preventive steps… just in case. For instance, there are limitations in place regarding how much rf energy cell phones are allowed to give off, and these amounts are much lower than the levels shown to cause damage in the aforementioned lab rats. Cell phone manufacturers are required to report the rf exposure of all their phone models to the FCC.
For my part, I'll stick to being annoyed by WiFi interference problems, and ignoring the strange voices being emitted from my computer speakers. Among other things, they're telling me to buy The Open Laboratory, the first-ever anthology of the best posts from science blogs in 2006. The voices think you should buy a copy, too, especially since one of my own posts is among the entries. You can order them from Lulu.com, a print-on-demand service. (It's a format that is very a propos for the blogosphere, I think.) Kudos to Coturnix of A Blog Around the Clock, for pulling the project together in record time. The voices hope this marks the beginning of an annual tradition!