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 be the most relevant isotope as far as doses was concerned and indicated the possibility "to follow this nuclide over long distances for several years." The organization also said it could take months or years for the isotope to reach "other shores of the Pacific". The survey by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) reveals that radioactive caesium released from Fukushima I Nuclear Power Plant reached the ocean 2000 kilometers from the plant and 5000 meters deep one month after the accident. It is considered that airborne caesium particles fell on the ocean surface, and sank as