In a radio interview marking the 20th anniversary of the world's worst civilian nuclear disaster, Gennady Onishchenko said work to assess the impact of the catastrophe would have to go on until after 2056, given that life expectancy in Russia averages 76 years.
"Some 1.5 million people in Russia have suffered as a result of exposure to radiation following the Chernobyl accident," he said.
Fourteen of Russia's regions were contaminated by fallout, with the western provinces of Bryansk and Kaluga among the worst affected.
Onishchenko said regular medical checkups were carried out in affected communities, and that work was under way to reduce the effects of radiation on agriculture. Some 50,000-70,000 studies are done annually to assess the damage caused to the wildlife and the environment, he said.