The whole beagle thing is outrageous. How could plutonium be good for any living organism? When I see these claims, I tend to regard it as a nuke industry hit piece. I'll find that cite to the cooperation between the WHO and IAEA as to mutually censoring health data.

As for Chernobyl, I don't think there will ever be a definitive answer. However, I think the paradigm for the study is because it is based on mortality while there are so many other reactions/results from radiation exposure.