I've met a dying Chernobyl first responder on a commuter train in Belarus, back in early 1990s.
These people never made it to WHO statistic as their deaths protracted over many years can not be directly attributed to the accident. As pro nuclear crowd would be happy to tell you, only couple dozen firemen died on the first day and that was it, making nuclear meltdowns almost benign incidents.
It is a pretty hard-hearted thing to say, but if the WHO doesn't think there is enough evidence to count his death in the Chernobyl statistics, what evidence does he have they are wrong? I mean, it isn't unprecedented for crippling damage to not surface for a long time (eg, asbestos/mesothelioma), but on the other hand cancer can strike at any age [0] and people struggle to attribute things to chance if they have a potential reason for it.
The WHO is using a statistical model to account for the fact that individual deaths might be cancer or might be something else. There is pretty concrete evidence that in terms of deaths nuclear meltdowns are benign, and the major concerns are land contamination and how big the exclusion zones need to be when things go wrong. Some of the better science-based counterarguments to nuclear I've heard go to contamination in the food chain.
Most of the studies among Chernobyl liquidators were based on monitoring the cohorts between 1994 to 2004. Very little was done form 1986 to 1991 at all.
The "never made it to WHO statistics" as the difference in cancer incidence rates and other problems after Chernobyl are so small that they are hard to distinguish from the background noise. A lot of work has gone into trying to document the actual effects, but the reality is that while there were initial large spikes in e.g. thyroid cancer among children, the cancers that spiked are ones with very high survival rates. The WHO estimates were initially very high, but keep being adjusted down because every year that goes is another year without a spike in deaths above expected levels.
The breakup of the Soviet Union caused much larger scale effects on life expectancy.
These people never made it to WHO statistic as their deaths protracted over many years can not be directly attributed to the accident. As pro nuclear crowd would be happy to tell you, only couple dozen firemen died on the first day and that was it, making nuclear meltdowns almost benign incidents.