Environmental impact of nuclear power materials decay, they release particles that can damage the body and lead to cancer, particularly cesium-137 and iodine-131. In the Chernobyl disaster, releases of cesium-137 contaminated land. Some communities, including the entire city of Pripyat, were abandoned permanently. One news source reported that thousands of people who drank milk contaminated with radioactive iodine developed thyroid cancer. The exclusion zone (approx. 30 km radius around Chernobyl) may have significantly elevated levels of radiation, which is now predominantly due to the decay of cesium-137, for around 10 half-lives of that isotope, which is approximately for 300 years. Due to the bioaccumulation of
Kyshtym disaster river, which had previously received 2.75 MCi (100 PBq) of deliberately dumped waste, and Lake Karachay, which had received 120 MCi (4,000 PBq). In the next 10 to 11 hours, the radioactive cloud moved towards the north-east, reaching from the accident. The fallout of the cloud resulted in a long-term contamination of an area of more than , depending on what contamination level is considered significant, primarily with caesium-137 and strontium-90. This area is usually referred to as the East-Ural Radioactive Trace (EURT). At least 22 villages were exposed to radiation from the disaster, with a total population of around