Effects of the Chernobyl disaster of caesium-137 in Europe) While the IAEA/WHO and UNSCEAR considered areas with exposure greater than 40,000 Bq/m, the TORCH report also included areas contaminated with more than 4,000 Bq/m of Cs-137. The TORCH 2006 report "estimated that more than half the iodine-131 from Chernobyl [which increases the risk of thyroid cancer] was deposited outside the former Soviet Union. Possible increases in thyroid cancer have been reported in the Czech Republic and the UK, but more research is needed to evaluate thyroid cancer incidences in Western Europe". It predicted about 30,000 to 60,000 excess cancer deaths, 7 to 15 Times greater
Radioactive tracer atomic nucleus of an isotope is unstable, compounds containing this isotope are radioactive. Tritium is an example of a radioactive isotope. The principle behind the use of radioactive tracers is that an atom in a chemical compound is replaced by another atom, of the same chemical element. The substituting atom, however, is a radioactive isotope. This process is often called radioactive labeling. The power of the technique is due to the fact that radioactive decay is much more energetic than chemical reactions. Therefore, the radioactive isotope can be present in low concentration and its presence detected by sensitive radiation detectors