Levels of radioactivity from the 1986 Chernobyl disaster are likely to remain high in parts of Northern Europe for 100 times longer than originally estimated, according to a report published in the journal Nature. Researchers from Britain and the Netherlands found that the environment is not cleansing itself as fast as expected, particularly in the case of one element, radioactive caesium. Restrictions on some foods in both the former Soviet Union and the U.K., including sheep, forest berries, mushrooms, and fish, may have to remain in place for up to 50 more years.