This is a very interesting topic but when I read the comments by Tartan Giant and Blacksheep I read the same stuff I read from the regulator doctors especially the FAA.
All is Ok
Are you kidding us or what I have met inbound acft where the crew have been breathing in engine oil leaking through the seals and thoses crews were not well and some still are not well enough to work. I was off work myself just from doing my job so those flying crews surely do suffer and Life on Mars is right this is a BIG PROBLEM.
However, the point someone else made about flying for 10,000 years and still being Ok is missing the point. Air contamination is not on all acft types and not on all flights but when it happens on the MD80, 757, A320 (V2500), 146 etc.. then its a problem so sure if you fly the 747 you might be Ok biddy but if you are regularly on a leaking plane your not going to be too good.
I attended a presentation on th &E& and Boeing knows this problem is coming to bite them so they WILL be using bleed free engines for economy and to resolve this issue.
So get real guys, when this happens, it WILL harm you and the lower the exoposure the worst it will be long term.
So when the company doctors say you'll be OK I say bull