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  #1  
Old 08-09-2005, 05:07 PM
zev_steinhardt zev_steinhardt is offline
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How does radiation kill?

I understand that certain elements are radioactive and give off radiation. IIUC, radition is simply that these elements give off particles (electrons, protons, etc.) as they decay in smaller elements.

But what is it about these particles that cause radiation poisioning and death? We come into contact with countless subatomic particles all the time and no harm comes to us. So, why is it that when they are radiated from an atom, they are suddenly lethal? What is it that these particles do to our bodies that "regular" particles do not?

Zev Steinhardt
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  #2  
Old 08-09-2005, 05:19 PM
Spatial Rift 47 Spatial Rift 47 is offline
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It's all about energy. Say I pick up a book from a table. The electrons in the atoms on the outer surface of that book come into "contact" with the electrons in the atoms on the outer surface of my hand, but neither group of electrons has enough energy to overcome the electrostatic repulsion (like charges repel) and knock things around.

Now, suppose I pick up a chunk of radioactive material. Suppose it's undergoing beta-decay, which means it's spitting out electrons. But these electrons have a much higher velocity (and therefore a higher energy) than the ones from the book, so they smash their way past the electrostatic replusion, and they may even knock an electron from one of my atoms, causing it to become an ion - positively charged. This means that whatever molecule the atom is in doesn't work anymore, and it either changes shape or breaks up. If that molecule happened to be a very important protein that I needed to fulfill some vital cellular function, then I have one less protein doing that function. If I sustain enough such impacts, the widespread lack of, say, oxygen processing or cell membrane repair will kill me.

The same argument goes for alpha particles (2 protons and 2 neutrons) or gamma rays (photons). That's why radios and microwaves and cell phones absolutely CANNOT give us cancer but ultraviolet radiation can. The radio and microwaves the appliances operate on simply don't have enough energy to knock anything loose, and no amount of intensity will give them that energy, while a single UV photon can start the ball rolling on skin cancer. This is what Einstein won the Nobel Prize for - the photoelectric effect.
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Old 08-09-2005, 07:59 PM
Canadjun Canadjun is offline
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Quote:
Originally Posted by Spatial Rift 47
The same argument goes for alpha particles (2 protons and 2 neutrons) or gamma rays (photons). That's why radios and microwaves and cell phones absolutely CANNOT give us cancer but ultraviolet radiation can.
I tend to lean towards the "cell phones don't give you cancer" side of the argument in the absence of any hard evidence for a link to cancer that I've been able to find. However, your second sentence above is a non sequitur. A great many things besides ionizing radiation cause cancer. It is not out of the realm of possibility that some other effect of the radio waves might be carcinogenic.
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Old 08-09-2005, 10:52 PM
David Simmons David Simmons is offline
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I think ionizing radiation kills cells and possibly also interferes with the body's ability to make new cells to replace the damaged ones. Every time a cosmic ray zips through our bodies, cells are killed along its path but the number of killed cells is small and the body is able to repair the damage, usually. In the case of severe radiation damage the body is unable to cope with the amount of injury.
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Old 08-09-2005, 11:02 PM
David Simmons David Simmons is offline
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Wikipedia is also a friend indeed, in this case.
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