Thursday, June 04, 2009

A radiation primer, part one. May the gods help you.

(Now that I've finished writing and proof-read this, I've considered changing the title to "Abandon hope, all ye who enter here.")

Yeah, you read that right. I still feel like crap and am working on Stealth Projects and spinning, so you're stuck with another of my topics from out of left field. In this case, the husbeast (who inspects nuclear reactors) and I (who lives with him and wonders just how dangerous his job is) have said for years we wished more average citizens understood the basics of radiation. Thanks to the media and some health care providers, people hear the word 'radiation' and their first response is, 'oh my god I'm gonna die'. And, well, what you should really be asking is 'what kind of radiation, and how much?' The answer is long, but I'm gonna try to keep it as brief as possible, and maybe entertaining into the bargain. Basically, we're gonna talk 'what kinds' and then get into the really annoying 'measurements' aspect. Proof reading this later, I've realized, 'what kinds' is taking forever, so I'm gonna do 'measurements and when to panic' tomorrow. 'Cause I'll probably still have a migraine. Plus, I think I need the husbeast to give this a proof-read, just to make sure I got the details right.

First, let us review. (Some of this should be familiar to long-term readers from my previous opus on the EM spectrum and visible light and color and reflecting spectra. This time we're branching out into more wavelengths.) So. The Electro-Magnetic Spectrum.

(I've got a really disturbing number of EM spectrum illustrations on my hard drive. As with most others, this one is from Wiki Commons.) As you see from the above chart, visible light is only a small part of a huge band of wavelengths; they go from low frequency (think sound waves) to high. The low-frequency stuff can mess you up, but generally it takes a good long time and (if you ask me) scientists really aren't quite sure what its effect on the body is. That "static field" over there at the far left can be, among other things, the magnetic field we're stuck into when we have an MRI done. I'm not saying an MRI is dangerous. I'm saying that if we lived inside one for two or three decades, it's likely something weird would happen and science has yet to figure out what. I doubt it's a priority. Likewise, the effect of fields created by high-voltage power lines is hotly debated, and research continues. Microwaves WILL heat your skin and burn you, as will the infra-red of heat lamps, salamanders (those super-broilers in restaurants) and, haha, sunlight. While all of these wavelengths will mess with you to some degree or other, their effects are pretty direct, so far as science has figured out so far.

Then there's visible light. We've discussed that before. Again, I doubt enough research has been done on exactly how visible light effects us. But I will say, as someone totally photosensitive who gets migraines, I'm not convinced it's entirely UV rays that causes me to shriek and put on sunglasses. But, by most analyses, visible light is considered harmless. (Though there have been warnings these last few years about the super-bright visible light spectrum produced by high speed photocopiers.)

All this is radiation, okay? The whole spectrum. The stuff we've discussed, including the visible light. All radiation. But it's rather run of the mill. We literally see it and live with it every day. We're getting to the radiation you need to freak out about, maybe.

Ionizing radiation.

Ionizing radiation is the stuff that damages your DNA and in some cases will literally knock bits off the atoms that make you up. Which, obviously, is really bad. The shift in the spectrum from 'regular' radiation to ionizing radiation happens in the UV (ultra-violet) band. Yes. The UV band that causes skin damage and cataracts that everyone has suddenly discovered in the last few years is bad. It's separated into UV-A, UV-B, and UV-C, and there is, as always, debate about which one causes the most damage. But you know how welders wear goggles to protect their eyes? It's UV light they're protecting themselves from. Every sunburn you've ever had was caused, mostly, but UV light; we've found in recent years that sunburns can trigger skin cancer, ultimately because UV light is ionizing radiation that can cause DNA mutation. Granted, it's mild mutation, often we never notice it, but it happens. (Notice tanning beds lurk in this portion of the spectra? So does sunbathing. I'm not sayin', I'm just sayin'.)

FYI, genetic mutation never turns you into one of the X Men. Which sucks ass because I'd love some super powers, but instead of the Power of Laundry I'm stuck with no wisdom teeth, good bones, and freaky retinas. Not enough for Xavier's School for Gifted Youngsters (every discussion of radiation needs a link to Marvel Comics). Usually, radiation damage causes nothing, or health problems of varying degrees of seriousness. Occasionally, one of those freak mutations causes evolution.

So, where were we? Oh, right. Ionizing radiation. After the UV portion of the spectrum, it gets kinda freaky, and we're into the realm of 'freak out' where the spectra lurk that people associate with the word 'radiation'. This doesn't mean you SHOULD freak out, because a lot has to do with dose. Most people don't know it, but two-thirds to three-quarters of our lifetime radiation exposure comes from the sun, earth, and other natural sources like radon gas. While it's not GOOD for us, the human body evolved soaking up a regular dose of all kinds of radiation, and so long as we don't up the dose significantly, our bodies will keep on keeping on. They're used to it. It's what they do.

X rays are next, and we all know those from breaking our arms or skulls or whatever. Yes, x rays are a kind of light. When we get an x ray, basically we're having our picture taken with a special kind of light; that x ray machine is just a super-fancy camera with a hell of a flash bulb. Before anyone thinks they're going to die of an x ray, guess again; unless you're an x ray tech, the vast majority of your x ray exposure comes from sunlight. Mostly x rays cause DNA damage, like UV rays. However there's some overlap in the spectrum between x rays and gamma rays.

I gotta wrap this up before one of you comes over here and kills me.

Lastly in the spectrum comes gamma rays, particle radiation, and cosmic rays. There are detailed, complex definitions for the different kinds, but I'm lumping them all together because their effect is the same in the human body and if I start on sub-atomic particles and decay rates and electron vs. neutron radiation one of you will stab me to death with a knitting needle.

These are the wavelengths that knock bits of your atoms off and cause most of the really horrifying damage that makes all of us freak out (including me). The kids who got stuck cleaning up Chernobyl died of this high-end gamma and particle radiation; other types of radiation exposure probably would have killed them too, but the gamma rays and particle radiation killed them first. Even at the unholy doses they received it took them a week or two to die; the movies where people are exposed to radiation and immediately keel over are just that - movies. Ditto for stuff glowing in the dark. Incidentally, the Chernobyl workers are thought to have died not so much from the radiation zooming around in the air, but from the radioactive particles of soot that they INHALED during the fire. Generally, external exposure is not nearly so serious as internal contamination caused by inhalation or eating contaminated food. Generally.

And, all right, I'm indulging in the tech stuff. There's also alpha and beta particle radiation, which act something like gamma but are more easily blocked; alpha radiation will be stopped by your clothing. Alpha and beta are both used medicinally quite a lot; a lot more than gamma, though it is used too. When I had a bone scan, I was given an alpha-particle emitting isotope that settled in my bones that they then took pictures of with very sensitive radiation detectors. That's how bone scans work. Kinda cool, huh? All particle radiation is caused by just that - actual bits of atoms. For alpha particles it's two neutrons and two protons. For beta particles it's electrons and positrons. They come from atoms that are so unstable they literally can't hang on to all their bits, and they just fall off. Some atoms naturally leak them; this leakage as known as decay. For instance, uranium 238 decays into thorium 234 by shedding alpha particles of neutrons and protons. (The numbers refer to the atomic weight; I'm including them for the one or two hard science types I get here, but the rest of you can ignore them.) Lots of atoms do this, and it's quite a natural process. It's where the majority of our everyday radiation exposure comes from. The danger is when mankind refines the stuff and puts it all in one place, like a bomb or a reactor, and then of course you've got LOTS of particles oozing off at the same time. It's still safe if you shield it properly, but, well, it's typical of humankind. No smarter than refining oil, just different.

All right. I think this is a good place to stop. Tomorrow's topic, "now that I know about radiation, why do I give a shit?"

12 comments:

walterknitty said...

There was an article in the Guardian a few weeks ago about the lingering effects of Chernobyl in the fallout zone in Britian and Wales. http://www.guardian.co.uk/environment/2009/may/12/farmers-restricted-chernobyl-disaster
Even now, more than 20 years later the human toll of Chernobyl is still unknown because the Soviet Union covered up a lot of what went down. There were men who had to dig a tunnel under the reactor that blew up to pour cement under it and shore up the floor so the radiation wouldnt leak into the groundwater. There were plans for a type of refrigeration unit to be placed under the reactor to help cool it (another reason why the tunnel was being dug) but that plan didnt come to pass. The weird thing? Prypiat has become a toruist destination of sorts. And the Exclusion Zone (I think) has become a nature reserve. There are still people who live in the area, mostly elderly who live in tiny villages.

Anyway, it's because X-Rays can damage your DNA, that women of reproductive age have to wear a lead apron when getting an X-Ray. Even though it's a different type of radiation (x-rays dont take good picutres of soft tissue) I had to wear a lead apron when I had my last mammogram in April.

Hope it's not TMI

Louiz said...

mmm, and don't forget something like the weather conditions when Chernobyl went pop. It essentially scooped up mildly radioactive dust and rained it over western England and Wales.

Recently the UK TV channel Dave (www.joindave.co.uk I think) showed a documentary where someone (can't remember who. I want to say Louis Theroux, but I think it wasn't him) went to Chernobyl, interviewed the people living there and watched what they ate. And was shamed into sharing a meal with his hosts, which his medical advisor told him later was a really really stupid idea.

Oh, and I had to wear a lead apron when my dentist x rayed my teeth - after checking I wasn't pregnant first.

historicstitcher said...

Rad II class would have been alot more fun if you were teaching it!

Netter said...

Did you know Botox has a therapeutic use? They inject it into the foreheads of some migraine sufferers and it cuts down the number of migraines. They think the squinting from glare triggers the migraine and paralyzing some of the facial muscles and nerves prevent the migraines. I also suffer from glare induced migraines (I always have a pair of sunglasses on hand), but they're also triggered by sinuses, too.

FeyRhi said...

I actually understood everything you wrote LOL.

Both my dad and my brother work at the Bruce Nuclear Plant here in Ontario. Usually when they start my eyes glaze over and they start to sound like the adults in a 'Peanuts' cartoon.

Donna Lee said...

I remember when Three Mile Island had its accident in 1978? 79? I'm not quite sure. I was in college and not too far from the plant. We had lots of lectures on why we should keep iodine pills handy and stay indoors if it rained. It's become a local joke, "those must be three mile island carrots, they're so big!"

janet said...

I'm the dork who really appreciated uranium 238 and thorium 234 and wanted to let you know that. Thanks!

Cam-ee said...

My uni lecturer told us that wavelengths could be divided into three basic categories in ascending order: useful, pretty and dangerous.

Shoveling Ferret said...

I skimmed because I think I'm sharing your migraine, but wanted to add the following utterly non-intellectual tidbits:

My husband continues to try to convince me that one day the MRI will give me superpowers, especially since I get the contrast injections.

Cherenkov radiation is scary beautiful. See the wiki for pretty pictures

Leonie said...

See I think you should be writing the chemistry text books that they completely numb our brains with because then we might actually remember stuff. However, despite not remembering any of that first hand, it was all very familiar :-)

Alwen said...

I think I'll have the home-schooled almost-10-year-old read these two posts and call it science.

I loves me a nice clear explanation!

baby nuke said...

You eat the gamma cookie, you put the beta cookie in your pocket, you hold the alpha cookie in your hand, and you throw away the neutron cookie.