Experts argue that not enough is yet known about the long-term health effects of the Chernobyl disaster to fully evaluate its impact on levels of thyroid cancer in the region.
Twenty years after the nuclear incident, estimates of the number of people who will die as a result has ranged from 9000 to 93,000.
It is still too soon to say what the final toll will be, Dillwyn Williams, a thyroid cancer expert from Strangeways Research Laboratories in Cambridge, UK, and Keith Baverstock, an environmental specialist from the University of Kuopio in Finland, say in the journal Nature.
Sixty-two deaths have so far been attributed directly to Chernobyl, and there have been 4000 cases of thyroid cancer, mainly in children and young adults, resulting in 15 deaths, they note.
While a draft version of the United Nation's Chernobyl Forum last year suggested up to 4000 deaths could be linked to the incident, this figure was based on the 600,000 people exposed to high levels of radiation.
The full report suggested another 5000 of the 6.8 million people exposed to lower levels could also die, but this figure did not appear in the 50-page executive summary. All of these data were from a 1996 study.
Explaining why the 4000 figure was given prominence in the report, Melissa Fleming, speaking on behalf of the International Atomic Energy Agency, said that it was to counter the much higher estimates previously made.
"It was a bold action to put out a new figure that was much less than conventional wisdom," she said. This estimate of 4000 deaths because of the disaster is also much lower than the figure of 93,000 given by Greenpeace in its evaluation of the Chernobyl impact published this month. The authors write: "If a full, independent study of the consequences of the world's worst nuclear accident is not established, and its results not widely published for all to assess, wildly differing claims will continue, and public mistrust of the nuclear industry will grow further."