I'm a bit suspect about what exactly was "inhaled." Specifically, it draws reference to "alpha particles." This isn't plutonium, per se, but one of the forms of radiation emitted from a radioactive substance.

There is a BBC documentary entitled "Nuclear Nightmares" which shows that radiation exposure of less than 100 mS has the unpredictable quality of reducing cancers. In graphing the correlation of radiation to cancer incidence, radiation exposure below 100 mS results in a threshold curve. On the other hand, maybe the documentary was a hit piece produced by the nuclear industry.