Evidently a German whose job was the monitoring of radiation in ground plants had travelled in a flight deck with a geiger meter and it went epileptic. The report was every extensive and quite scary.
RAT5 I've heard umpteen versions of that story ( usually as told in the UK gent was from Calder Hall or Aldermaston) over the years. Frankly if someone whose job was meant to be radiation montoring doesn't know what levels he or she would expect to see at high alt then they are no expert, the numbers have been known since Auguste Pickard.
https://en.wikipedia.org/wiki/Auguste_Piccard
As far as radiation and studies disappearing down a black hole as an inconvenient truth
, there's plenty of data out there on the open medical sites on the internet thingy. There are some interesting studies yet to be resolved/finalised but that whilst radaiation levels at crusing altitude are high vs. ground level I'm afraid that in general the epidemology doesn't support a
hidden radiation threat conspiracy.
Now back to fumes...