awblain - quote- 'Organophosphate components of turbine oil are essential to ensure the extreme reliability, longevity (and thus safety) of engines; however, they are very toxic to the nervous system. Nothing else that would get into cabin air is anything like as nasty.'
In fact there are many other things which are just as nasty as TCP, for example acrolein - an aldehyde which may be formed on the decomposition of turbine engine oils. Carbon monoxide (in non lethal doses) can also give rise to some of the symptoms and would fit more with the instances where pilots are revived by oxygen. Carbon monoxide doesn't really explain the long term effects but suggest have a look at acrolein.