Now that Chernobyl is in the news again due to the HBO series, many people are once again asking this question. About three years ago my dad, a retired nuclear physicist, took a deep dive into the numbers and came to the following conclusion:
approximately 26,000 cancer deaths are attributable to the Chernobyl accident. This is more than six times the figure quoted by UN agencies and less than 10 times that quoted by Greenpeace.
To understand how he came to this conclusion, read “Calculating the Uncountable Deaths from Chernobyl” by Edward A. Friedman, starting on page 17 of the Winter 2016 edition of Public Interest Report, the newsletter of the Federation of American Scientists.
UPDATE: Also see a follow up exchange with Dr. Alexander DeVolpi which appeared in the Spring 2017 issue of the newsletter.