Cesium is a radioactive fission product generated in nuclear power plants and is disposed of as liquid waste. The recent catastrophe at the Fukushima Daiichi nuclear plant in Japan has increased the 137Cs and 134Cs concentrations in air. soil and water to lethal levels. 137Cs has a half-life of 30. https://www.roneverhart.com/Traditional-Karate-Do-Okinawa-Goju-Ryu-Book-1-The-Fundamental-Techniques-by-Morio-Higaonna-Preowned/