*This may sound outrageous, but it is actually what is claimed by many "health physicists." The remarks quoted below come from the article Japan's Cut-Price Nuclear Cleanup:
“100 millisieverts [about 20X above normal background radiation in Japan] is the dose we use as a cut-off to say we can see a significant effect on cancer rate in very large epidemiology studies. The numbers have to be large because the individual increase is minuscule. But, she added: “I would be far more worried about these workers smoking or feeling under stress due to the fear of what radiation might do to them. That is much more likely to have an effect on any one person's health.”
But Ian Fairlie, a London-based independent consultant on radioactivity in the environment is among those who have challenged the view of 100 mSv as a reliable threshold. Citing studies of tens of thousands of Japanese A-Bomb survivors, Fairlie concluded in a blog post last year that “very good evidence exists showing radiation effects well below 100 mSv”.