Radioactive beef from Fukushima meat cows (then Miyagi, then Iwate, then...) was first in the news in early July. Then, the culprit was very quickly identified as radioactive rice hay that was stored outside when Fukushima I Nuke Plant started to spew out radioactive materials.
First they said the rice hay was fed to the cows because there was nothing else to feed due to supply disruption after the March 11 earthquake. Then it turned out that rice hay was integral part of fattening the meat cows before they were sold to the market.
Then the news broke on August 19 that some meat cows from Fukushima were highly radioactive even without radioactive rice hay.
And then it turns out that 4,000 such cows may have been shipped since the accident by one cattle farmer who owns cattle farms in Namie-machi and in two other towns (Tamura City and Katsurao-mura). The radiation level on the farm in Namie is very high, as you can read in the Kahoku Shinpo article below.
Well, that instantly doubles the number of meat cows potentially contaminated with radioactive cesium. I say potentially, because most of the meat has been consumed already and there's no way to test it.
From Kahoku Shinpo, local Fukushima paper (8/21/2011):
Regarding the 4 meat cows from a cattle farm in Namie-machi in Fukushima Prefecture that exceeded the provisional safety limit for radioactive cesium (500 becquerels/kg), the Fukushima prefectural government disclosed on August 5 that the meat from 5 additional cows from the same farm contained radioactive cesium exceeding the provisional safety limit. From this farm in Namie-machi, total 229 cows including the 9 that were contaminated were shipped to Yokohama City between March 15 and April 19.
The farmer who owns this cattle farm in Namie-machi also owns farms in Tamura City and Katsurao-mura, and total 4,000 cows in his three farms were shipped after the Fukushima nuclear accident.
From the 5 cows, 593 to 786 becquerels/kg of radioactive cesium has been detected. The first 4 cows tested 513 to 997 becquerels/kg. The contamination level is similar.
Upon the news of radioactive contamination, the cattle farming section of the Fukushima prefectural government investigated the three farms on August 19 and 20. At the farm in Namie-machi, the entrance to the barn measured 15 microsieverts/hour maximum; 35 microsieverts/hour radiation was detected from the grass growing outside, and 5.5 microsieverts/hour radiation at the feed trough in the barn.
At the farm in Katsurao-mura, they measured inside the barn and on the grass outside, and the storage facility for the dried hay. The air radiation level 1 meter off the ground was between 0.5 to 0.8 microsievert/hour. At the farm in Tamura City, the air radiation level 1 meter off the ground near the entrance to the barn was 0.3 microsievert/hour.
The farmer says he fed the cows with imported hay, not the rice hay. The cause for cesium contamination is not yet known. However, cows lick the dirt to obtain minerals. They may also have eaten the grass outside when the radiation level was higher.
The farm in Namie-machi is located in the "planned evacuation zone" designated on April 22, but the contaminated cows had already been shipped by then. Fukushima Prefecture measured one cow each from the farms in Katsurao-mura and Tamura City on April 28 when the farmer shipped the cows, but radioactive cesium was detected at only 60 to 90 becquerels/kg, below the provisional safety limit.
The farmer has already evacuated outside Fukushima, and there is no cow left in the farms. The national government was going to lift the shipping ban on the meat cows in Fukushima Prefecture, but it decided not to when the radioactive cesium contamination [without radioactive rice hay] was discovered.
Before the Fukushima accident, the amount of radioactive cesium in beef in Fukushima was max 0.055 becquerel/kg. In the post-Fukushima Japan, over 9,000 times the pre-Fukushima level of radioactive cesium has to be considered "safe". (Data on radioactive cesium in Fukushima beef from Japan Chemical Analysis Center database, in Japanese.)
Namie-machi and Kazurao-mura have been designated as "planned evacuation zone". Part of Tamura City has been designated as "evacuation-ready zone". The national government still plans to "revise" these designations and return the residents, as Fukushima I Nuclear Power Plant is now "stable".
15 microsieverts/hour radiation would result in the annual cumulative radiation exposure of 131 millisieverts, and that's external radiation only.
Poor cows. After having been fattened up to the max for sale, suffering high cholesterol and high blood pressure, they had to be zapped by radiation...