I do find this quote problematic: ""It is difficult to have this debate unless we know for sure whether this radiation is from Fukushima or whether it is natur

I do find this quote problematic: ""It is difficult to have this debate unless we know for sure whether this radiation is from Fukushima or whether it is naturally occurring background radiation," said Pieter Franken, founder of the Japan office of the environmental monitoring organisation Safecast." As others have pointed out, the sievert is already weighted with respect to danger. In other words, the source makes absolutely no difference at all. If you somehow managed to get a huge radiation does from, say, bananas (which are fairly radioactive due to the potassium) it wouldn't be any better or worse than the same dose from a nuclear power plant. That said, it always surprises me that there's no panic over naturally radioactive foods, like bananas. It's curious that the "unnatural" aspect seems to cause a disproportionate amount of the fear. FWIW, I enjoyed a nice, naturally radioactive banana as I wrote this.