The Chernobyl nuclear plant in Ukraine exploded 20 years ago, but the disaster will continue for another 60 years in the form of slow deaths from cancers. The accident released a plume that dropped radioactive particles throughout the Northern Hemisphere. No one has pinned down the expected toll--estimates range from thousands to tens of thousands, revealing disagreements in the way the figures should be calculated and limitations in current knowledge about radiation damage.
The most commonly reported figure is 4,000 deaths, which derives from a 2005 United Nations press release. Curiously, it called the 4,000 a "new" number from a study by "an international team of more than 100 scientists"--even though the cited work was from 1996 and was authored by only seven scientists. "Certainly the 1996 paper was never meant to make the headlines of the newspapers 10 years later," remarks lead author Elisabeth Cardis of the World Health Organization's International Agency for Research on Cancer in Lyon, France.