Radioactive cesium likely from the Fukushima nuclear disaster was detected last year in a survey of ocean waters and fish off Niigata, Shizuoka, and Iwate prefectures, the government announced on Aug. 3.
“Even if taken internally, the radiation levels detected are not a risk to human health,” the Ministry of Education, Culture, Sports, Science and Technology stated. The ministry added it believes the small amount of contamination detected even in the Sea of Japan off Niigata was probably originally airborne material that made it to coastal waters through rain and river courses.
The survey is done every year in ocean waters near nuclear power plants nationwide as well as nuclear fuel-related facilities in Aomori Prefecture.
The survey found in May last year that there were 9.1 millibecquerels of radioactive cesium per liter of seawater off Omaezaki, Shizuoka Prefecture, near the Hamaoka nuclear plant, and in December, the survey found two becquerels per kilogram in a type of flounder in the area.
Also in May last year, the survey found dried sea floor dirt from the southeast of Sado Island, near the Kashiwazaki-Kariwa nuclear plant, was contaminated with 31 becquerels of cesium per kilogram.
In the ocean off Yamada, Iwate Prefecture — an area surveyed in connection with the nuclear fuel cycle facilities in Aomori Prefecture — 0.7 becquerels per liter of seawater were detected in May 2011.