This Fukushima radiation contamination calculation seems to be VERY controversial issue. There is difference between ICRP and ECRR2010 risk valuations and that difference multiplication factor is about 1000!
ECRR2010 calculations can be found on fairewinds pages, ICRP calculations (probably) on IAEA pages.
This problem with alpha radiation measurement is real, and measuring just bequerells is very difficult to link real nuclide activity.
If I have understood correctly, iodine ja cesium are gamma radiators and easy to measure with Geiger-tube. Measuring highly radiating alpha particles needs complicated particle filters and "lead-chambers-or-what-ever-it-is" to measure activity accurate.
I suppose that many of the top nuclear physicist are reading this forum and this thread. Unfortunatelly they are mute, because this topic seems to be "hot potate" on nuclear science.