I really could have used co-blogger Allyson's advice about skeptic etiquette earlier this year. At a recent party, a bunch of my non-science-geek friends and I got to moaning about all the time we spend in front of our computers. I've always thought one of the ironies of my life was that when I was growing up, my parents yelled at me to not sit so close to the TV and I now earn my living . . . sitting too close to what is, essentially, a TV. Lots of us older folks have eye fatigue from it, especially from the old CRT screens that really were pretty much the same as a TV. But one of my fellow partiers loudly declaimed that we were all being irradiated by our computers too, and that she'd bought this special amulet to turn back those rays and all the other irradiation modern life subjects us to and "other negative energies." The best part was that the woman she bought the amulet from is able to recharge it remotely and is always adding new protections to it. Best money she'd ever spent, she said.
Moments like this just make my brain hurt.
We'd already had the LHC-black hole discussion in which I'd successfully quashed that panic, but my bullshit meter was almost off the dial with this. I had to really bite my tongue not to say something scathingly sarcastic to someone I didn't know, and it was all I could do not to roll my eyes like a Kewpie doll. It was odd (and kind of heartening) how the room went really silent though. And then I was chagrined to realize I didn't really have enough hard data at my fingertips to rebut everything she said, and that was embarrassing. I know about the scientific studies refuting the dangers of overhead high voltage wires, but I only have a vague grasp of how CRTs and LCDs work. So I thought I'd use my ignorance (shameful, I know) to offer up a quick lesson in how to refute this particular species of New Age Quack, diplomacy not included. (Check with Allyson about that.)
Part of the problem is that people get freaked out by the idea of radiation in general, not realizing there are many types of it and that we are, indeed, being irradiated all the time, not just by our electronics. That darn visible light bombards us all the time! The electromagnetic (EM) spectrum is huge and only the higher end, beyond the visible spectrum, is strong enough to be truly dangerous. The harmfulness of radiation depends on its energy, whether it's powerful enough to knock electrons off an atom's orbital shell, turning it into an ion: ionizing radiation.
For example, the wavelength in sunlight that tans you or, in excess, gives you skin cancer is not the visible spectrum or we'd all have fried eyeballs (which is what happens when you look directly at the sun because the light is concentrated through the lens of your eye onto a small spot on your retina, like a bug under a magnifying glass). It's UV or ultraviolet radiation, just next door to the violet end of the visible spectrum (hence the ultra prefix) that makes you sizzle. And that's the least of its effects. Over the long term, UV light can cause cellular and molecular changes that result in cataracts, permanent changes to skin and fibrous tissues, and skin cancer. Because it causes chemical changes in the body, the effects can be exacerbated by "birth control pills, tetracycline, sulphathizole, cyclamates, antidepressants, coal tar distillates found in anti-dandruff shampoos, lime oil, and some cosmetics."
The most common sources for ionizing radiation are nuclear reactions natural and man-made (fusion and fission) and natural radioisotopes. Don't know an isotope from an antelope? An isotope is a version of an element that has a different than usual number of neutrons (a different mass number) but the same chemical properties. A radioisotope emits enough EM energy to strip away the normally tightly bound electrons from an atom, making it a charged particle, like x-rays. Only the shortwave end of the EM spectrum has enough energy to do this—not the electrons coming out of your CRT TV.
While it's true that every appliance in your house that uses an electric current is surrounded by an extremely low frequency (EMF) electrical field, that radiation is of the non-ionizing sort, even the microwave. The health hazards of this type of radiation are probably negligible in the low concentrations we're exposed to.There are some exceptions, of course. Stick your head in the microwave and you'll cook yourself, but that's because microwaves excite the water molecules until they give off heat. You won't be radioactive afterwards, just cooked. Likewise infrared radiation, which makes some beautiful photographs!). IR filters allow viewers to see differences in ambient temperature, which is why they're used in night scopes, but the radiation itself is not up to much more in everyday concentrations than heating you up a little.
Much like the radiation that's coming off your computer and TV screens. CRTs are not so popular now that flatscreens have gotten cheaper, but the initials stand for Cathode Ray Tube, which is the source of the "ray" part that seems to freak people out. That ray is a stream of electrons produced by the heated cathode filament and steered by electromagnetic coils. Those electrons pass through a fine-mesh mask and strike a screen coated with phosphors, temporarily goosing them into a more excited state, making them glow. So that electron energy beam is mostly absorbed by the phosphors on the screen. Some of it does escape, but it's mostly hanging around the glass screen making it staticky and attracting dust motes. Because the first thing a free electron (not to be confused with a free radical) wants to do is bind to something. It's lonesome, just a little negatively charged particle looking for its love match in the orbital shell of some other atom. If there are enough atoms with odd-numbered electrons around (like copper's 29), they pass the electrons around like a swingers party and you get a current. That's the crackle you hear when the screen turns off, and why you sometimes get zapped when you touch a CRT display. The free electrons find you more attractive than the glass.
So, those pesky free electrons—how harmful are they? Um, depends on the source energy (see comments below). There is a type of radiation that involves free electrons (beta decay), but these are high-energy ionizing particles that come out of of the nuclei of radioactive materials like plutonium, not out of hot filaments in a cathode ray tube (which is essentially like a lightbulb). The truth is, you're exposed to more radiation risk in a routine x-ray or in the radon-choked basement of your house than from a cathode ray tube. That's because not all radiation is alike.
Because radiation exists as both particles and waves, its potential for damage depends on how much energy it has. The higher the frequency, the more energy it has and the more potential for damage. That's because some radiation—radio waves, for instance—either passes harmlessly through you or is reflected off your skin, like some wavelengths of light; they're low energy, long wavelength. High levels of exposure to even low-frequency/low energy waves can have an effect on biological systems, but the that seems mostly negligible at everyday exposure levels. Some EM radiation, like x-rays, pass through the softer tissues of your muscles and organs but are stopped by the denser bones, leaving those blank, unexposed spaces you see on x-ray film that show your skeleton. When x-rays strike the atoms in your tissue, including those in your DNA molecules, they have enough energy to knock the electrons off, creating charged ions that alter the usual chemical reactions in your body, or even break the DNA up. The cells die or work in weird ways. If this happens in enough cells, mutations or other reactions that we read as radiation sickness or cancer can occur. In small doses though, the body is self-correcting enough to heal whatever damage is done in the name of seeing that fracture in your tibia or the denser mass of cancer tumors.
LCDs are an entirely different fish in some ways, but operate similarly. These displays are built in kind of a sandwich style with the liquid crystals in the middle between layers of glass, filters and electrodes that supply the current. The material that gives LCDs their acronym are crystals that have lost some of their positional rigidity. Nematic liquid crystal molecules, which are usually rod-shaped, are still more organized than isotropic crystals, but both are semi-liquid. Application of a current causes them to realign or "untwist" themselves into various configurations that block or reveal the light which also passes through vertically and horizontally aligned polarizing filters. The pixels in this case are a substrate of indium-tin oxide. If you've got a liquid crystal display (LCD) monitor, you may have noticed that it attracts significantly less dust to its display surface than your old CRT. This tells you that there are fewer free electrons floating around looking for other atoms to bind to (or that your house is a lot cleaner than mine is). That's because instead of spraying electrons gatling-gun style, in LCDs the current is channeled in a grid to different parts of the screen in a closed circuit.
Plasma displays have a similar structure to LCDs, but the medium that's excited by the current is, obviously, plasma: charged gas confined in "cells" sandwiched between several layers of glass and other materials. Since plasma displays ultimately use UV radiation to excite their pixel phosphors, they contain a protective layer of magnesium oxide (the same compound found in both Milk of Magnesia—as magnesium hydroxide—and some electrical cables. Versatile stuff!) that blocks the ionizing UV radiation) but is transparent to the visible spectrum. So you're still probably getting zapped less by your plasma TV than by an old CRT, though the CRT "leakage" is the standard by which safe radiation is measured for electronics.
The upshot is that none of the radiation emanating from your appliances is the kind emitted by nuclear materials, so you're not going to get cancer or radiation sickness from it. None of it is of sufficient energy to fry so much as a mosquito, let alone cook your brain. In fact, one thing most people overlook is that we are ourselves walking electrical fields. Our brains are electrochemical dynamos, zipping signals along our synapses millions of times a second, the proverbial telephone switchboard. Our own electrical field created by the movement of current between cells is slight, but the fields inside our cells are as powerful as lightning bolts. One day, we may actually become our own local area network. That little shock of electricity between people that we talk about is not only a metaphor.
Okay, now that you know you're not being bathed in deadly ionizing radiation or high levels of non-ionizing radiation from your computer or TV or microwave, what about that "charging remotely" thing? How's that work? Wifi? Radio waves? Light? Microwaves? Hey, maybe that's frying our brains! Slap a radiation hazard sign on all those psychics' doors! But thanks to Allyson, at least you can be polite about it.