18.5 becquerels/kg of radioactive cesium has been detected from tomatoes grown in Kashiwa City in Chiba Prefecture. The survey was done by one of the largest supermarket chain AEON.
From Savechild.net (12/23/2011):
The large supermarket chain AEON announced on November 8 that it would conduct a more thorough analysis of radioactive materials in food items, and it has been publishing the results on its homepage. There has been occasional detection of radioactive cesium in marine products, but never in vegetables. However, according to the result published on December 22, 18.5 becquerels/kg of radioactive cesium was detected from tomatoes grown in a contract farm in Chiba Prefecture.
The tomatoes in question were tested on December 15, according to the AEON's webpage.
Savechild.net reports that a quick phone call to AEON revealed that the tomatoes came from a contract farm in Kashiwa City which is located in the high-radiation northwest corner of Chiba Prefecture.
Savechild.net also speculates that at this time of the year these tomatoes must be grown in a hot house.
So where could radioactive cesium have come from? Water? Soil? Fertilizer? (I hope they weren't using rice hay as soil cover...)
AEON's page that lists the results of vegetable surveys is here. It looks the detection limit for tomatoes (as well as other vegetables) were higher in the earlier surveys, so it is possible that radioactive cesium had been there in the earlier samples but not detected.
AEON's page that lists the results of the radiation survey is here.
On a separate piece of news, AEON's subsidiary AEON MALL has won the contract for a redevelopment project right behind the Onahama Port in Iwaki City in Fukushima Prefecture, according to Fukushima Minpo. Promoting Fukushima rice and produce has paid out well for AEON Group, it looks.