"The total number of deaths already attributable to Chernobyl or expected in the future over the lifetime of emergency workers and local residents in the most contaminated areas is estimated to be about 4000. This includes some 50 emergency workers who died of acute radiation syndrome and nine children who died of thyroid cancer, and an estimated total of 3940 deaths [...] lifetime of about 600,000 people under consideration." - WHO https://apps.who.int/mediacentre/news/releases/2005/pr38/en/index1.html
The older Linear-No-Threshold model had predicted that small doses of radiation would have a small chance of causing harm. From watching Hiroshima, Chernobyl, and nuclear accidents, our new models have thresholds below which radiation has no observable effect over the lifetime.Chernobyl was a disaster but its death toll is equivalent to a month of North America's opioid epidemic.