help me measure radiation in food

hi there. i live in japan and have been teaching at a university in tokyo for more than fifteen years.

since the nuclear meltdown in march i have managed to get a geiger counter (gamma scout) from germany and have been informally learning about how to use it.

average levels range from 0.06 uS/h to .2 in Tokyo, but in nearby Chiba just on the border of Tokyo there are hotspots on the ground where you easily get 1.0 to 5.0 uS/h.

my friend drove up north to help out in the restoration effort and showed me a picture of 2.1 uS/h as he drove down the highway (moving, in the car) in fukushima prefecture.

clearly there has been a great deal of food contamination all over northern japan and even in areas close to tokyo. there have been news reports about some vegetables and meat, but i suspect that contamination is more widespread.

how can i check? i have looked through the forums and the consensus seems to be i cannot use my geiger counter to measure the safety of food... but isnt there a way to tell the difference between say 1 BQ and 200 BQ per liter of milk, for example?

or would i be better off to just get a spectromoter / isotope identifier and simply reject everything with any level of CS137 as that seems to be the major player in this game....

any advice on what sort of machine i could purchase (a microraider?) to accomplish this task.

thank you.