Caesium-137 or approximately 44 μg/kg) of caesium-137 (and 950 to 1400 rads), they die within 33 days, while animals with half of that burden all survived for a year. Accidental ingestion of caesium-137 can be treated with Prussian blue, which binds to it chemically and reduces the biological half-life to 30 days. Caesium-134 and caesium-137 were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Chernobyl disaster and the Fukushima Daiichi disaster. As of 2005 and for the next few hundred years, caesium-137 is the principal source of radiation in the zone of
Radiation effects from the Fukushima Daiichi nuclear disaster in the unit-3 spent-fuel pool were reported at 140 kBq of radioactive caesium-134 per cubic centimeter, 150 kBq of caesium-137 per cubic centimeter, and 11 kBq per cubic centimeter of iodine-131 on 10 May. TEPCO have reported at three sites 500 meters from the reactors that the caesium-134 and caesium-137 levels in the soil are between 7.1 kBq and 530 kBq per kilo of undried soil. Small traces of plutonium have been found in the soil near the stricken reactors: repeated examinations of the soil suggest that the plutonium level is similar to the background level caused by atomic bomb