Not sure. What I do know is that I have stupidly been breathing very dangerous fumes for 35 years, in confined spaces, without a proper understanding of the risk. Have you read the warnings on White Spirit? Central nervous system damage!! I've been cleaning brushes with the stuff, every few minutes, whilst painting thousands upon thousands of figures, for vast stretches of time, in very ill-ventilated spaces, thinking that the warnings I originally read had not changed, and so not bothering to read the new ones. All the while allowing little puddles of the stuff to evaporate beneath my nose, under a hot lamp, then creating another puddle every few minutes to clean my brush. Ignorance really is bliss, until it is stupidly dangerous.
Maybe I have been lucky, and stopped just before it really chewed my grey matter to pieces? Only some sort of medical tests would tell. I can't really assess my own mind!
What I know is that I am now too afraid to finish the figures I was working on. Or that I will only do so in the kitchen with the door wide open!
Then I am making the move to acrylics like every one else. Why did I stubbornly stick with the devil I knew? Because I didn't realise what a devil it was!