Aerotoxic Syndrome – A Hazard of Airline Travel

by | Sep 26, 2017 | 2017, Environmental Health

Written by Joyce Smith, BS. There is an identified cause-effect relationship between exposure to contaminated “bleed air” in air craft cabins and health hazards including cognitive impairment to the aircrew.

Aerotoxic Syndrome is caused by the inhalation of contaminated airline cabin air that is caused by “bleed air” and other fumes entering the aircraft cabin air supply.  Bleed air contamination has been recognized since the introduction of the bleed air system in the 1950s and is still a health hazard today1,2 . With the exception of the Boeing 787, today’s aircraft all use the bleed air system to provide cabin ventilation. Commercial airlines routinely pump or “bleed” compressed air from airline engines to cabins where crew members inhale this unfiltered air that is contaminated with pyrolized hydraulic fluids and synthetic jet engine fuels. The contamination includes a neurotoxic organophosphate by product. A small 2016 study by Reneman et al 2016 3 demonstrated that cognitive impairment in the participating aircrew was directly associated with the number of airline flights and the extent of compromised integrity of brain white matter.

Researchers conducted two independent studies 4 (A and B) to review the circumstances and symptoms of a cohort of aircrew who worked in a pressurized air environment and to determine whether contamination of pressurized cabin air with pyrolyzed jet engine oil and engine aircraft fluids was responsible for the symptoms experienced by the aircrew. A table of effects was then used for categorizing symptoms and reviewing other sources of data related to aircraft fluids and selected other conditions.

The United Kingdom pilot unions provided 2005-2009 data on demographics, flying history, flight deck air quality history, health effects and other comments. Study A included the 219 pilots who reported either specific health effects (n=142) or no health effects (n=77). Study B was a case study analyses of 15 potential cabin air contamination incidents that provided extensive study data. The incidents were validated by medical findings and diagnoses, and found to be consistent with acute hyperventilation and hypoxia oxygen deficiency in the body) 5.

Study A. A table was developed to categorize acute and chronic symptoms. Adverse health issues among the 142 Study A participants included cardiovascular, gastrointestinal, fatigue, neurobehavioral, neurological, and respiratory effects.

Of the 274 pilots that were initially surveyed, 36 (13%) had died or had experienced chronic ill health leading to a permanent loss of fitness to fly. The types of adverse effects and diagnoses described were: neurobehavioral, 64%; neurological and general factors (e.g. chemical sensitivity, chronic fatigue, gastrointestinal (GI) symptoms), 53%; respiratory, 39%; and cardiovascular, 25%. The chronic cohort (13%) reported ill health at 37–433% above the controls. In all, 10% of the pilots had flown the BAe 146 for under 2 years, 54% for 3–10 years and 19% for over 11 years.

Study B found that, in all, 80% of events involved fumes only, 53% happened on flight deck, and 27% on both flight deck and cabin. All events occurred during engine operation with 80% occurring during a climb or descent, in 7 different aircraft types and 87% of the events were linked to oil leakage. Symptoms, ranging from in-flight incapacitation to impairment, were reported in 93% of the events with 73% involving pilots, and 33% including full or partial incapacitation of two pilots. Long term adverse effects included cardiovascular, neurobehavioral, neurological and respiratory symptoms, chronic fatigue, multiple chemical sensitivities, aerotoxic syndrome, cancer, soft tissue damage and chemical exposure. Nine pilots either became unfit to fly or died. Passengers reported adverse effects in 27% of events.

Over 3.5 billion passengers and 0.5 million aircrew were exposed to low levels of engine oils in 2015 6-8. There is an obvious need for a clearly defined internationally recognized medical protocol in which occupational syndrome and disease are recognized, and health and environmental data are collected.

Aerotoxic syndrome was first described in 2000 9 and has not been recognized by the medical establishment as a syndrome with a legitimate ‘cause- effect” relationship. However, the data from this present study are consistent with previous reports which accept that the Bradford Hill causation criteria are met in eight out of nine categories (the exception was a dose-response relationship)10. This study clearly identified a cause-effect relationship for exposure and symptoms and diagnosis; therefore, 10 recognition of this new occupational disorder and a clear medical investigation protocol are urgently needed.

Source: Susan Michaelis, Jonathan Burdon, C. Vyvyan Howard. Aerotoxic Syndrome: A New Occupational Disease? Public Health Panorama 3(2) 2017: 141-356

© The Author(s) 2015 Creative Commons Attribution 4.0 International License

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Posted September 26, 2017.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

  1. REDDALL HA. Elimination of engine bleed air contamination. SAE Technical Paper;1955. 0148-7191.
  2. ICAO C. 344-AN/202. Guidelines on education, training and reporting related to fume events Montreal: International Civil Aviation Organization. 2015.
  3. Reneman L, Schagen SB, Mulder M, Mutsaerts HJ, Hageman G, Ruiter MB. Cognitive impairment and associated loss in brain white microstructure in aircrew members exposed to engine oil fumes. Brain imaging and behavior. 2016;10(2):437-444.
  4. Michaelis S, Burdon J, Howard CV. Original research AEROTOXIC SYNDROME: A NEW OCCUPATIONAL DISEASE? PANORAMA. 2017:198.
  5. Bagshaw M. Health Effects of Contaminants in Aircraft Cabin air. Summary Report v2.7. 2014; https://www.asma.org/asma/media/asma/Travel-Publications/Air-contamination-health-effects-report-v2-7-Apr2014.pdf. Accessed May 25, 2017.
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  7. ifalpa.org. International Federation of Airl Line Pilots Association. 2017; https://www.ifalpa.org/. Accessed May 25, 2017.
  8. Federation ITW. International Transport Workers’ Federation. 2017.
  9. Winder C, Balouet J-C. Aerotoxic syndrome: adverse health effects following exposure to jet oil mist during commercial flights. Paper presented at: Towards a Safe and Civil Society, Proceedings of International Congress on Occupational Health2000.
  10. Ramsden JJ. Contaminated aircraft cabin air: aspects of causation and acceptable risk. J Biol Phys Chem. 2012;12:56-68.