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
Chernobyl disaster being taken up by fungi such as "Cortinarius caperatus" which is in turn eaten by sheep whilst grazing. The United Kingdom was forced to restrict the movement of sheep from upland areas when radioactive caesium-137 fell across parts of Northern Ireland, Wales, Scotland and northern England. In the immediate aftermath of the disaster in 1986, a total of 4,225,000 sheep had their movement restricted across a total of 9,700 farms, in order to prevent contaminated meat entering the human food chain. The number of sheep and the number of farms affected has decreased since 1986, Northern Ireland was released from