The very poor reporting on TV and the comics (sorry, that's newspapers to the less discerning) about the radiation problems shows that a headline is much more important than actual fact and explanations. Maybe it is true that, despite most of the population having at least ten years of "education", the general public are too dim to understand real data and its meaning even if said data is interpreted in a simple way by known experts. Sadly, the experts are as guilty as the journalists. We watched an expert from the ANU, a fellow we've know for over 20 years, spouting the most blatant propaganda vis-a-vis Global Warming. It seems that, like the Cheshire Cat, words mean what the sprooker whats then to mean and to the Devil with unbiased logic. Disagreement is tantamount to treason ... (For further entertainment in this vein and a Oscar winning performance of hubris, I recommend the current production, "The Mad Monk", at the local theater in Canberra.)
Back to radiating ...
Unfortunately, it's a bit more complicated if you ask, "dosage of what?" Gamma, X-ray, Beta, Alpha, Neutron radiation? Hence, the use of the Sievert which is a unit of "Equivalent Dose" - Alpha weights 20 times the others. Which part of the body? Hence, the "Effective Dose" - eg: gonads weighted 20 times skin. How long was the exposure? Hence, the "per year" factor.
This page (http://www.bbc.co.uk/dna/h2g2/A2922671) seems to do a reasonable job of explaining some of the complications. There are difficulties over unit of measurement and their interrelationships - Rem, Rontgen, Gray, Sievert, Becquerel, Currie, just for starters.
The fact that some of the foods in the area are radioactive comes as no surprise - they ALL are. Trouble comes when there is no comparison with what the "normal" levels were before the earthquake and tsunami. Maybe the foods were not measured before the event - I don't know at this stage. The same comment applies to the drinking water - everywhere (which includes Australian sources of water).
The average nuclear radiation from a person is reported as, something like, 400 microSv per year. You might as well suggest that it is dangerous to go to a football match where you would be surrounded by all those people next to you and all radiating nasties and giving you cancer ... what bollicks!
Interestingly, radon levels have always posed a problem and, not least, in the UK. The building methods in the UK include the wide use of Breeze Blocks which are made, in part, of the ash from conventional power stations. These release radon. The heath authorities in the UK commissioned a detailed study which measured the levels radon in homes in England and Wales. Not surprisingly, the results showed that people living in geographical areas where granite rock predominates were subject to greatest exposure to radon - Cornwall 700% higher than Norfolk. This is a natural phenomena ...
Unfortunately, we don't seem to be able to face up to the simple fact that our civilization is electricity based and we will, inevitably, need nukes to power our iPads ...