Deaths due to the Chernobyl disaster and other diseases with longer time latencies following the release of radioactive debris from the disaster. A United Nations' International Atomic Energy Agency (IAEA) study estimates the final total of premature deaths associated with the disaster will be around 4000, mostly from an estimated 3% increase in cancers, which are already common causes of death in the region. Some non-governmental organizations, many with staunch positions on the spectrum of the nuclear power debate, have claimed numbers up to a million excess deaths caused by the nuclear disaster. UN and other international agencies such as the Chernobyl Forum and the World
Caesium which could create wide-ranging contamination, gradually put some of these caesium sources out of use. Caesium-137 has been employed in a variety of industrial measurement gauges, including moisture, density, levelling, and thickness gauges. It has also been used in well logging devices for measuring the electron density of the rock formations, which is analogous to the bulk density of the formations. Caesium-137 has been used in hydrologic studies analogous to those with tritium. As a daughter product of fission bomb testing from the 1950s through the mid-1980s, caesium-137 was released into the atmosphere, where it was absorbed readily into solution.