The amount that the food chain gets contaminated is the issue here. If the amount is negligible, such that it does not substantially increase the disease rate in humans, then it is a non issue.
For example, if you build up 10^-15 grams of cesium in tiny creatures, then by the top of the food chain it will only increase concentrations by a maximum of 3-6 orders of magnitude simply through conservation of matter. This radioactivity also decays over time so it is also less than this maximum. I disagree that such a small amount of radioactive material would have any impact on us since humans regularly have to deal with sources of radiation such as background radiation, the natural radioactivity in the soil, radiotherapy, and xray machines.
Also the cancer that the head of tepco had could be merely coincidental.
Evven if the situation is 4 times worse than they suggest, that's still only 1200 tons per day. In order to affect the food chain, it would realistically need to be two orders of magnitude worse than they are suggesting, so a factor of 100, which would turn a few nanograms into a few hundred nanograms, or maybe even a microgram.
Although some of this is speculation, i think it is a reasonable hypothesis considering that the amounts in question are so small relatively. Chernobyl did not even increase disease rates substantially worldwide. Also I think the fact that it can buildup in the foodchain indicates some natural biological resistance to radioactivity . Humans have done so many nuclear bomb tests that fukishima should be a drop in the bucket.
if you have some study that has done the calculations on the buildup of radioactivity from fukishima in animals, and that it is enough to increase disease rates in humans, then I would be very interested in seeing it as it would prove my premise is entirely wrong.