Toxic fumes from oil leaks in plane engines are causing chronic fatigue, sleeplessness, memory loss, and cognitive deficiency.

The British Pilot’s organisation BALPA held a conference entitled “The International Aero Industry Conference on Contaminated Air Protection Air Safety and Cabin Air Quality” in April 2005. According to this article which appeared in Dagbladet.no (Norway), "Seventeen leading experts signed a petition at the conference, appealing to the aviation industry and the authorities to take the problems of contaminated air on planes seriously ... to take note of the following conclusion of the conference:

This is a working environment issue which results in chronic and acute illness among the aircrew, both cabin attendants and pilots.
Unacceptable effects on aircrew’s health is a significant flight safety problem.
We are also concerned that flight passengers suffer from similar symptoms to those found among air crew.