"Children from nursery schools and kindergartens up to junior high schools in Yokohama City had already been fed the beef from Fukushima since late April. Then the news of radioactive beef from Minami-Soma City broke a few days ago."
(..)
"Then, in late June, the councilman reported the result of the meeting at the Board of Education. All the beef from Fukushima that went to school lunches in Yokohama from April 23 to June 7 came from the planned evacuation zone in Fukushima. There were 916 cows from the zone. None of them exceeded 5,000 cpm in surface radiation, but none was tested zero. All were contaminated. The information was obtained by tracing the unique identification numbers for the cows.
On July 9 in Japan, the news broke that the meat from a meat cow from Minami Soma City was found with radioactive cesium of 2300 becquerels/kg, almost 5 times the provisional safety limit (500 becquerels/kilogram).
The councilman's post on July 9:
All Fukushima-grown beef that was served in school lunches in Yokohama City was contaminated. The contamination that was checked at the time of shipment from Fukushima Prefecture was only the surface radiation of a live cow, and there was no information as to the contamination after the cow was processed into meat. School children have already ingested this meat."
http://ex-skf.blogspot.com/2011/07/beef-from-fukushima-to-be-tested.html