Routine events
Attribution of illnesses to environmental factors requires real evidence, not just, I smelled something and then found I had renal cancer etc. i assume that flight departments have access to pilots medical histories but am not sure. Do they? Unscientifically based speculation can raise issues, but when these sorts of environmental concerns are investigated they usually turn out to be distributed randomly, and to have no basis on environment. Love Canal which was a cause célèbre for years in the US was never shown to have caused any disease. Cancer and vascular disease are the big killers in western countries and should be expected to occur everywhere.