[dreadgeek]

I wanted to add one more thing to the post on radiation.

So, when dealing with radioactivity there's a couple of things to keep in mind:

What kind of radioactive particles are we talking about. (How energetic are they.)
What kind of protection you have.
How long you're exposed.
How often you're exposed.
How intense is the radiation.

So, we spend most of our days bathed in radiation we can see--namely visible light. Visible light, however, is not particularly energetic so it doesn't really hurt us provided the source isn't too strong (which will still hurt your eyes). Radio, infrared and microwaves are even *less* energetic than visible light. We live our lives bathed in those sources of radiation to know real ill effect.* You wouldn't want to be IN a microwave or stand right on top of a very powerful microwave source and, say, camp out there but your cell phone or your radio won't cook you.

Above the visible spectrum, the photons get more and more energetic.** More energetic photons have more opportunity to cause damage and this is why intensity, type of radiation and length of exposure as well as how often you are exposed becomes relevant. DNA has a *remarkable* ability to repair itself. In fact, part of why we are SO resilient as living things is because DNA, by its very nature, has the ability to recreate itself.*** However, even DNA can get overwhelmed. If you are in a, say, field of high gamma radiation for hours at time your body is simply going to have SO many damaged strands of DNA that it will not be able to repair itself effectively. Thus you start to get things like cancers.



* I know people think that cell phones cause problems but they don't. Cell phones are operating in the microwave band and before you think "hey, we use microwaves to cook things!" what is *actually* happening is that the microwaves cause the molecules in the food stuff (like fats and water, both of which are dipole molecules). Think of dipole molecules like little molecular magnets, one side is negative and the other positive. In the presence of an oscillating magnetic field (like microwaves) they will rotate to align themselves with the field. This rotation creates heat and the molecules bump into other molecules which causes them to move. Temperature is the average kinetic energy of molecules or atoms in a substance so the more the molecules rotate, the higher the temperature.

** From radio to gamma rays keep in mind that we are talking abou the same stuff. Gamma rays aren't one thing and radio waves another. Pump enough energy into a radio wave (i.e. increase its frequency) and it will not act 'like' a gamma ray it will *be* a gamma. These are all just photons at different energies. Another word for talking about EMF waves is frequency. To get a sort of visceral feeling for what is happening, use a very familiar experience--hearing a siren. As you get closer to a sound source the pitch rises and the noise level increases. As the sound source retreats the pitch falls and the noise level decreases. The waves get shorter on the approach and longer as you and the siren pull away from one another. Now, what is happening with light is *not* that as you move toward a light source the waves get shorter. Rather, gamma rays are shorter (higher frequency) than radio waves (lower frequency). A low wavelength--literally the length between the peaks and troughs of the wave--in water is less disruptive than a high wavelength. Gamma rays are more disruptive because their higher energy means they are more likely to react with some atom in your body. Visible light rays are just gamma rays slowed down and mellowed out or radio waves with a Type A personality.

*** Part of why DNA is so good at self-repair is because of its very structure. DNA is made up of four amino acids making four 'letters'--ATGC. Now, the interesting thing about DNA is that if one point on the strand is A then its opposite will be T, if one strand is G the opposite will be C. Not might, not sometimes, but IS. This means that as long as one side of the strand is correct, the other side of the strand will be correct. Genes are simply patterns of repetition of those four letters. Another type of damage that radiation can cause are replication errors. The difference between, say, Huntington's chorea and not is, if memory serves, less than a dozen repeats.

Cheers
Aj