Personal Testimony.
I'm a 757/767 pilot for BA. RR 535-E4 engines. On a number of occasions I have smelt the fumes.
On most of those occasions I have found my cognitive functions degraded. I liken the effect to the way one can sometimes make a journey (to work for instance) and one can't remember it. As though I was functioning without long term memory....Thankfully it passes within 12 hours.
The footdragging on this issue by all concerned is quite saddening. A lot of pilots on my fleet avoid the aircraft. As a junior pilot I therefore get a disproportionate amount of 'exposure'.
No doubt the key personel involved are fans of the film "Thankyou for Smoking"