Incomplete combustion of these oils, fluids, and other organics is a potential source of carbon monoxide (CO). Elevated CO levels can be a danger to health and flight safety as well as an indicator of mechanical problems such as leaking seals. Another group of contaminants with hazard potential are tricresylphosphates (TCPs), members of the organophosphate chemical family. TCPs are known for their anti-wear properties and are popular additives in engine oils and hydraulic fluids. Like many organophosphates TCPs are neurotoxic. Laboratory testing has confirmed that these chemicals can be generated (in the case of carbon monoxide) and made airborne (in the case of TCPs) at temperatures typical of an operating aircraft engine^2-3.

A recent review of organophosphate toxicity defines a disorder called organophosphate-induced chronic neurotoxicity (OPICN) resulting from single high acute exposures or small subclinical doses of organophosphate compounds. Neurologic symptoms of this disorder are consistent with those in numerous anecdotal reports by flight attendants and pilots in a number of countries following “smoke in the cabin” incidents. However, exposure data from such incidents has not been collected, and no systematic studies have been done to assess the consistency of symptoms and their correlation with specific exposures. These are the type of studies called for in the NRC report.

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¹National Research Council. The Airliner Cabin Environment and the Health of Passengers and Crew.
Washington DC,National Academy Press, 2002.
²van Netten, C. and Leung, V. "Comparison of the Constituents of Two Jet Engine Lubricating Oils and Their Volatile Pyrolytic Degradation Products." Appl Occ Env Hyg, Vol. 15(3): 277-283 (2000).
³van Netten, C. and Leung, V. “Hydraulic fluid and jet engine oil: pyrolysis and aircraft air quality.” Archives of Environmental Health, Vol 56(2): 181-186 (March/April 2001).
⁴Abou-Donia, M.B.Organophosphorous ester induced chronic neurotoxicity.