A young woman said she was dizzy for a full week and then she lost the hearing in one ear.  Later this was a diagnosis for her, and a tumor was found thereafter.  I would suspect that the tumor started up with exposure to 2-butoxyethanol and that there was continuous exposure for the week.  That it came out of nowhere and grew rapidly.

I heard of Uncle Ray who was perfectly healthy until he went to a sports stadium for some game.  He started feeling unwell.  They found a brain tumor and it rapidly grew to the size of a grapefruit and he died in just a few months.  I suspect he got exposed 2nd hand to someone hollering at the game who was nearby him, and the vapors got into his eyes:  second hand solvent exposure