Exposure to triaryl phosphates: metabolism and biomarkers of exposure.

The leakage of tricresyl phosphate-containing engine lubricants into aircraft cabin air, either from worn or defective engine seals or under normal operating conditions, is a serious concern for both the health and safety of the cabin occupants, since the oil contains one to five percent tricresyl phosphate (TCP) esters, known neurotoxins. The exposure of pilots is a particular concern since their impairment can affect their safe operation of the aircraft. Mass spectrometric (MS)-based protocols for documenting exposures of individuals are described that entail a rapid purification of the TCP-modified plasma enzyme butyrylcholinesterase (BChE). Following protease digestion of BChE, the modified active site peptide is characterized by MS analysis. Approaches for identifying safer engine oil additives are also described. Some general comments regarding the necessity of improving the quality and safety of the cabin air supply are presented.