It's true that ingesting a radioactive particle is different from exposure to "frank" radiation. However, I'm a little skeptical of their claim that there is a direct and linear relationship between exposure to radioactive isotopes and risk of death. The real measure is the extent to which you can detect that variation in cancer death rates is likely to be due to exposure rather than chance. I had thought that below a certain threshold, ingestion of radioactive isotopes (some of which have short half-lives), wouldn't be differentiable from random chance. Rarely are things like this ever linear. So when they say:
As the crisis in Japan goes on, there are an increasing number of sources reporting that 100 milliSieverts (mSv) is the lowest dose at which a person is at risk for cancer. Established research disproves this claim. A dose of 100 mSv creates a one in 100 risk of getting cancer, buta dose of 10 mSv still gives a one in 1,000 chance of getting cancer, and a dose of 1 mSv gives a one in 10,000 risk.
I'm very skeptical of this kind of claim. In fact, it's probably wrong. There isn't a linear relationship:http://www.ccohs.ca/oshanswers/phys_agents/ionizing.html
Especially since mSv is a measurement of the relative effect of radiation. The becquerel is the absolute measure of emission from the radation source. There's not a direct relationship between becquerels and mSv!
That's one of the reasons why I'm down on nuclear-opponent groups. Sure the industry may underplay risks, but there is a certain amount of physical verifiability that can be done. Nuclear opponents seem to massively exaggerate even the little things.