Caesium-137 alienation around the Chernobyl nuclear power plant. Together with caesium-134, iodine-131, and strontium-90, caesium-137 was among the isotopes distributed by the reactor explosion that constitute the greatest risk to health. The mean contamination of caesium-137 in Germany following the Chernobyl disaster was 2000 to 4000 Bq/m. This corresponds to a contamination of 1 mg/km of caesium-137, totaling about 500 grams deposited over all of Germany. In Scandinavia, some reindeer and sheep exceeded the Norwegian legal limit (3000 Bq/kg) 26 years after Chernobyl. As of 2016 the Chernobyl caesium-137 has decayed by half, but could have been locally concentrated by much
Accident rating of the Fukushima Daiichi nuclear disaster radioactive material have also been released into ground and ocean waters. Measurements taken by the Japanese government 30–50 km from the plant showed caesium-137 levels high enough to cause concern, leading the government to ban the sale of food grown in the area. Tokyo officials temporarily recommended that tap water should not be used to prepare food for infants. In May 2012, TEPCO reported that at least 900 PBq had been released "into the atmosphere in March last year [2011] alone". Several of the plant's workers were severely injured or killed by the disaster conditions resulting from the earthquake. There