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 caesium-133 to co-define the second and the metre. Since then, caesium has been widely used in highly accurate atomic clocks. Since the 1990s, the largest application of the element has been as caesium formate for drilling fluids, but it has a range of applications in the production of electricity, in electronics, and in chemistry. The radioactive isotope caesium-137 has a half-life of about 30 years and is used in medical applications, industrial gauges, and hydrology. Nonradioactive caesium compounds are only mildly toxic, but the pure metal's tendency to react explosively with water means that caesium is considered a hazardous material,