Hi David,
Here's a chart showing ionizing radiation exposures for different situations/objects, etc. Scroll down a couple or three posts to see it. Click on it to see an expanded version.
Wolf K.
On 3/22/2011 9:35 AM Wolf K spake thus:
My initial reaction (and I haven't had time yet to properly evaluate this): I'm skeptical.
o Sources? The sources for the chart are given here:
I'll look into it later. In the meantime, mark me unimpressed. Radiation is no laughing matter, *especially* the low-level doses that are shrugged off by sites like this. Those are the ones that really cause the most damage. (While we're quoting authorities on the subject, let me direct you to the studies on BEIR--the biological effects of ionizing radiation---that were done in the 1960s-1970s, and established, basically, that there is *no* minimum safe dose of radiation in the case of chronic exposure. Sorry, no links to give you, but I'll find those as well.)
Er, skeptical of the orders of magnitude shown? Or what?
If you're that skeptical, buy your own Geiger counter, and start checking.
AFAIK, all checkable by you, if you're willing to trust a Geiger counter, or a sensitive dosimeter.
I also know, from way back when I was doing chemical engineering, that, yes, bacvkground radiation is a ) surprisingly high; b) varies a lot (by factor of about 5, not including outliers); c) and that "ordinary" human-made sources of ionising radiation such a dental X-rays are much higher than back ground.
BTW, I knew that coal-burning power plants dump a hell of a lot of C14 into the atmosphere long before I became curious about Three Mile Island.
That's "most US authorities", maybe. I haven't checked.
It's the SI unit, which is legal everywhere, including the US, and is standard for most things. It's the measurement system used by science and by international manufacturing (but is translated into local units in the US). Named for Rolf Sievert:
That means that 1 SV is the absorption of 1 Joule of radiation energy per kg mass. That's quite a lot, actually.
Mistyping. Happens all the time.
It's a general science magazine published by Kalmbach. Competes with other general science/technology science mags. I don't think they have any axe to grind, except perhaps the generic one of "People should know more science" If you want more authoritative sources, visit Scientific American or Science (AAAS rag).
Well yes, I'm not denying that. But the anxiety induced by that finding is IMO more than a little excessive. What "no minimum safe dose" means is that there is no safe place on Earth when it comes to ionising radiation. Not even your own body, which harbours C-14, K-20, Ca-41, I-129,131, Cs-134/etc (chemically like Ca), and several other radioactive isotopes. Which is something people just don't think about.
To put it another way: other risks that you take without a second thought are far more likely to harm or kill you than chronic low-level radiation exposure.
FWIW: until fairly recently, I refused more than one dental X-ray every two years. My dentist now has a very-low-dose-machine that takes a panoramic X-ray, like a mini-CAT-scan. Takes about 5 seconds for the gizmo to rotate around one's head. Cool!
Interesting tidbit: Isaac Asimov in an essay about interstellar travel using suspended animation pointed out that there's an absolute limit to how long you could survive such a trip, even assuming perfect maintenance of the life-support systems. It's about 20,000 years. Why? Because over 20,000 years, the K-20 in your body will have caused so much damage to your tissues that the necessary biological processes could no longer be sustained. An effect of "chronic exposure to low-level radiation" with a vengeance.
Wolf K.
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