Caesium out of the body relatively quickly in sweat and urine. The remaining 90% has a biological half-life between 50 and 150 days. Radiocaesium follows potassium and tends to accumulate in plant tissues, including fruits and vegetables. Plants vary widely in the absorption of caesium, sometimes displaying great resistance to it. It is also well-documented that mushrooms from contaminated forests accumulate radiocaesium (caesium-137) in the fungal sporocarps. Accumulation of caesium-137 in lakes has been a great concern after the Chernobyl disaster. Experiments with dogs showed that a single dose of 3.8 millicuries (140 MBq, 4.1 μg of caesium-137) per kilogram is
Koeberg Alert strontium-90, which are responsible for most of the radioactivity of spent nuclear fuel Caesium-137 beta decays to barium-137m (a short-lived nuclear isomer) then to nonradioactive barium-137, and is also a strong emitter of gamma radiation. Caesium-137 has a very low rate of neutron capture and cannot be feasibly disposed of, but must be allowed to decay. The committee is also told how both the Tweelopiespruit and Wonderfonteinspruit in the Krugersdorp-Randfontein area have been contaminated by uranium mine tailings caused by South Africa's nuclear and mining industry. 16 March 2009, a leak of radioactive gases from Pelindaba is reported by NECSA.