In summary, the study found that there was no evidence of increased cancer rates among the Chernobyl population as a whole or in any of the restricted areas. There were 4000 cases of thyroid cancer, mostly in children and adolescents at the time of the accident, but all of them have recovered. Persistent myths and misperceptions about the threat of radiation have resulted in "paralyzing fatalism" among residents of affected areas. Bennett explains that there have been 4000 cases of thyroid cancer, mainly in children, but that except for nine deaths, all of them have recovered.
We know which radionuclides were released, how and where they were absorbed by the body and how long their biological lifetime is. All the death toll estimates cited here are based on this knowledge.
It's known that 50 people died from ARS as a result of being in close proximity to the source of the radiation, but beyond that, it's all just estimates as far as how many people got cancer as a result of the accident. There are many environmental factors that can cause an increased risk of cancer (not just radiation), and it's difficult to impossible to determine with absolute certainty exactly how many cases of cancer since the disaster were caused by the radiation vs. other factors that changed around that time frame. Not only that, but it's likely that some potential causes of cancer are still unknown, and therefore not all of the variables are necessarily accounted for. Furthermore, some organizations have a political agenda, whether that's downplaying or exaggerating the risks associated with nuclear energy, and their "estimates" could be distorted in favor of their bias.
I'm not sure that looking at the dose a person receives is really that useful. The increase in thyroid cancer was not really an issue about the dose, it was the fact that the dose was in a form that was readily ingested and incorporated into our physiological processes. Really we need to know what isotopes were released and the potential that people may have ingested or inhales these isotopes. I used to live near Sellafield in the UK and during their annual leaks, radioiodine was always a cause for concern. However despite the problems there was never any convincing evidence of higher rates of cancer in the area.