[RWebb]

radiation contamination is not forever, but extends for several half-lifes of the isotope; the ones at issue here are I, Cs, and of especial concern here maybe Plutonium

both atomic (nuclear physics) and chemistry are at work - the chemistry affects how each isotope will bind to other things in the environment; and be concentrated by living organisms (which in turn means biology needs to be added to the mix of science - not just physiology, and various levels of ecology, incl. popn. ecol (predators eat WHICH prey, now?); ecosystem ecology (how do various chemicals, those isotopes, travel thru ecosystems) - now add in some oceanography (currents & etc.; storms) and...

unhealthy radiation levels were detected in bottom dwelling fish today - dunno if it is a food species or is eaten by a fish that is eaten by a fish.. that is a food species
- that is just the human health issue; there may also be damage to the nearby (or even remote) ecosystem to be considered

at a minimu, if you travel to Japan, you should avoid most sushi, seaweed (nori), algae, and breast milk

If I had to make a quick bet, I'd bet the BP oil spill will wind up being worse than the Tokyo Elec. radiation releases...