And don’t forget all the Soviet subs that were dumping off the Sea of Japan for decades. There is probably some stuff left from them.
If humans are exposed to ionizing radiation, damage results. Sometimes it is genetic damage that is not expressed beyond the individual or offspring. Sometimes it is genetic damage that only shows up later in the offspring. There are obscure illnesses documented from the Ukraine following the Chernobyl disaster. Increased early dementia, cardiac death, leukemia and cancer along with “a host of other illnesses” and leaps in all illnesses as a result of depressed immune response.
It’s safe to say that if nuke sub reactor material gets into the food chain, then it causes damage for the remaining time it undergoes radioactive decay. But increases in illnesses in the human population would exist but not be identifiable has having come from a specific source.