COuld be interesting but then again could just be a scaremongering exercise, but in Panorama on the Beeb tonight there is an investigation into whether leaks in engine oil could be exposing passengers to fumes while flying. They have one ex-pilot recounting how he nearly passed out because of it on time.
Now i think to be honest the industry knows that this happens but it the amount is in such small quantity as to be deemed safe for travel.
This is backed up by the swobs they seem to have taken. Still, if i was a pilot after plenty of flights, i wouldn't want to have it all the time