The Grey Area That Never Benefits The Victims

Aviation's "Wounded Canaries" or Aerotoxic syndrome: The Scientific Controversy

Is aerotoxic syndrome a new occupational disease? Described more than twenty years ago based on symptoms and disorders reported to doctors by numerous pilots and flight attendants, it is not recognized as such. It is still the subject of scientific controversy. This is "a denial", says Eric BAILET, a former pilot who founded the Association of Victims of Aerotoxic Syndrome (AVSA) in 2016. “Pilots are poisoned by the air they breathe on board aircraft," he explains. The pressurization system used on virtually all commercial aircraft today was adopted in 1955. Almost immediately, undesirable effects on crews were reported and the cause was established: the air supplied was taken from the engine compressors and contaminated by leaking lubricating oil. When heated to high temperatures, these oils can release dangerous compounds, including neurotoxic organophosphates.

Note: The following is part 2 of the article written by ©Patricia Oudit and ©Eliane Patriarca, published at (part 1©) MEDIAPART on October 31, 2023 (English version here ); (part 2 ©) “Santé & Travail” November 7, 2023. (Translation in parts/versions 1 and 2 by BBeaumont).

Eric BAILET joined easyJet in 2002 and began to suffer from a series of health problems in 2009: migraines, blurred vision, dizziness, vertigo, nausea, asthenia, stomach problems, etc. Between increasingly frequent sick leave, he continued to fly. But in 2015, as he was making the last of his four flights for the day, he was taken ill... In a state of confusion, he was unable to concentrate on his instrument panel. His co-pilot was also in disarray. Just like the rest of the crew. A nauseating smell, with a distinct smell of moldy, dirty socks, had invaded the cockpit and cabin: it was a fume event, (or fume incident), which can manifest itself by faint or strong fumes that aircrew learn to identify (ed: nowadays) during their training. On that day in 2015, the captain managed to land the Airbus: "We can thank the automated controls!" says Eric BAILET, "… but if we'd had the slightest technical problem, we wouldn't have been able to cope. “The proof: "We disembarked with the engines running!”

Deprived of his passion for flying - he was declared unfit to fly in 2018 and forced to retire. Convinced that he had been slowly poisoned, Eric filed a complaint against XX for endangering the lives of others in 2018 with the Paris public prosecutor's office. His application for recognition as an occupational disease was rejected by the French National Health Insurance (since aerotoxic syndrome is not included in the relevant tables), and then again by the Toulon court last April.

The controversy had a new episode in 2022, with an expert report requested by the examining Magistrate of the judicial public health division in Paris. Three university professors, including a specialist in occupational pathologies, reviewed the abundant scientific literature on the subject. "Oil leaks are inevitable", they write, "due to wear or leaking engine seals". They go on to point out that "… there is, therefore, continuous exposure to low doses under normal flight conditions", an exposure that can be "major" in the event of a smoke event. As aircraft are not equipped with "detection systems" to detect air contamination, "nor filters to eliminate contaminants", chronic exposure could, in their view, "… only they can produce a threshold for the onset of health problems in the medium and long term".

While the airlines unanimously continue to deny and try to overthrow the health impact of fume events, the conclusions of this report are in line with those of Australian researcher Susan Michaelis, Ph.D. (Note: more about Ms Michaelis and her work in the French original article). To better document exposure and improve medical monitoring of aircrew, Susan Michaelis and a medical team she works with published a medical protocol suggesting what needs to be done in the event of intoxication following a fume event: "You should immediately, ideally within 2 to 4 hours, carry out more or less extensive medical tests depending on the severity of the damage", she recommends, stressing "…the need to carry out blood tests to assess, among other things, the level of cholinesterases, a biomarker of neurotoxic damage by organophosphates".

Nothing of the sort is mentioned in the medical protocol adopted by Air France this year dealing with "smoke/odor and fires". Michel Klerlein, occupational physician and coordinator of the company's medical department, is perfectly comfortable with this choice. He does not recognize any scientific basis for the airborne toxic syndrome: "Why ask for a cholinesterase assay when 100% of the studies carried out on cabin air show that there are no organophosphates or toxic products?”

→ Editor’s question: Which studies, funded by whom?

The latest twist in the controversy is the expert report published in October by the French National Agency for Health, Food, Environmental and Occupational Safety (Anses). Referred to in 2019 by AVSA and the pilots' unions, the Anses states that flight crews are exposed to "multiple particulate and gaseous pollutants that may be linked to the materials used, the operation of the aircraft and in particular the ventilation system, the operations carried out on the ground and in flight, etc.". The experts nevertheless disagree and disapprove of the low number and quality of existing epidemiological studies, and conclude from other scientific literature that there is "little evidence to link a specific syndrome to air contamination by engine oils".

→ Editor’s question: which scientific literature, funded by whom?

→ Editor’s note: “little evidence” does not mean “no evidence”.

Henri Bastos, Scientific Director of Health and Work at the Anses, explains: "While the symptoms described by the flight crews are not called into question, there is currently no medical consensus on aerotoxic syndrome, due to the wide variety of specific symptoms reported. It is therefore not a pathology in the nosological sense.” (Note editor: Nosology is the branch of medical science that deals with the classification of diseases of the term, as recognized in the international classification of diseases, i.e. = ICD-10). In its report, the Anses recommends new studies on cabin air quality, citing as an example the Avisan project, which it is co-financing and which will be conducted with Air France over one year. (Note: I was unable to verify this project, when I do I will update).

Editor’s question: How unbiased is a study going to be with an airline involved?

But how can we explain such a dissonance in the understanding of symptoms and disorders? “Low-level exposure does not produce clinical signs, so it's easy to conclude that there is no contamination," points out a hospital practitioner specializing in occupational pathologies, drawing a parallel with the difficulties in establishing the link between occupational exposure to pesticides and chronic illnesses in farmers.

“This is a constant in environmental health when faced with an emerging pathology. What's more, in all the cases where we don't want a causal link to be established between exposure and disease, there are always loopholes in the monitoring and traceability of exposure and a lack of detection systems. A grey area that never benefits the victims.”

For more in-depth information or if you are seeking help, please contact AVSA (French) and check out the website UNFILTERED (English and Spanish), where you can find science, testimonies, court cases, documentaries, medical and laboratory protocols, books, and more. Please also support our petition (several languages).