I tend to agree with Less Hair's take on these matters (cabin air toxicity, that is, as opposed to the separate issue of overexposure to cosmic radiation - clearly less hair might be a symptom of the latter!).
And in relation to that last offered example German report, it occurs to me that the known overfilling of the hydraulic system may have been dismissed a little prematurely. Which systems get a particular and fresh working over on approach? Sure, excess deicing fluid often oozes from where it's been hiding on descent and approach too, but lots of hot hydraulic oil out of design limits caused by overfill would be high on my list for investigation.
Some very strange and nasty smells can come from hot hydraulic oil getting out to the wrong places - I first learned that on farm tractors 45 years ago - but you can step out of those till the smell subsides, and simultaneously retain fully brain function to quickly work out what just went wrong!