Twenty years after the nuclear incident, it is still not clear what the full effect on people exposed to radioactive materials will be.
The estimated number of the people that will die as a result has ranged from 9,000 to 93,000 deaths. The experts say it is too early to say what the final toll would be. Sixty-two deaths have so far been attributed directly to Chernobyl.
The full report of the UN's Chernobyl Forum last year suggested another 5,000 of the 6.8 million people exposed to lower levels would also die.
The aftermath of the atomic bombs dropped on Nagasaki and Hiroshima by the US was that 20 years is too soon to be able to predict all the consequences of fallout.
The radiation exposure was different in Japan - where the bombs led to whole body radiation. After Chernobyl, exposure was largely from radioactive particles inhaled or ingested by people living nearby - except for those working near the reactor.
The thyroid cancers have been linked to high levels of radioactive isotopes of iodine. But radioactive iodine can also concentrate in the salivary glands, the stomach and the breast tissue.
Drs Williams and Baverstock add: "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."