Fume events are the dark belly of the aviation industry. The stuff used to lubricate turbofan engines is incredibly toxic when breathed in, literally orders of magnitude more potent than simple kerosene fumes.
There are a variety of lubricants, but it is believed that the primary contributor to the problem is the organophosphate (Tricresyl phosphates - TCP / e.g. Durad 125[1]) added as an anti-wear additive.
TCP is a known neurotoxin:
"It is a toxic substance that causes neuropathy, paralysis in the hands and feet, and/or death for humans and animals alike. It can be ingested, inhaled, or even absorbed through the skin." [2]
Below is a presentation based on a PHD thesis on the subject with a lot of detail: