Wasabi plants, like these, in Fukushima prefecture were found to contain substantial amounts of radioactive iodine. C.K. Koay/Flickr hide caption itoggle caption C.K. Koay/Flickr Shots - Health News Japan Finds More Foods Tainted By Radioactive Material March 28, 2011 This week Japan's health ministry released a list of 99 different food products that had tested positive for radioactive iodine-131 and cesium-137 in Tokyo and five other prefectures. Some of those foods might surprise you.