According to the best estimates there will be 20 cancers over the next 40 years due to radiation from Fukushima ... http://blogs.nature.com/news/2012/05/world-health-organization-weighs-in-on-fukushima.html
Bowel cancer in Japan was about 20,000 in 1975. Allowing for population growth it should be about 23,000 now. But it has soared to over 100,000. Why? Japans change of diet. In particular red and processed meat which the 150+ expert authors of the World Cancer Research Funds 2007 report says cause bowel cancer. So which is more dangerous, something which causes 20 cancers in 40 years or something which adds 3.2 million extra cancers over 40 years. The evacuation was cruel and totally out of proportion to the miniscule risk. Compared with red and processed meat, tobacco and alcohol, radiation is pretty much a wimp in the cancer stakes.
If you consider how many lives have been saved by Japan having 30% of its power coming from clean energy instead of filthy dirty carcinogenic coal fired power stations then the cost benefit ratio is also clear.
Japanese bowel cancer rate increase data is from:
But my 100,000 figure above comes from 2008 globocan data.