Irregular hours and ionising radiation
In France, more than 30,000 people, including pilots and flight attendants, work in aircraft cabins and cockpits. Flight crew members are particularly prone to working irregular hours and night shifts, which is known to have health effects. This is combined with exposure to ionising radiation from cosmic rays and sunlight, which increase with altitude in particular. An analysis of the literature, supplemented by the results of IARC monographs on cancerous diseases, led to the conclusion that there is an increased incidence of certain types of cancer, such as skin cancers (squamous cell carcinoma and melanoma) and leukaemia, among flight crew members. According to the literature and the IARC monographs, solar and cosmic radiation may be the cause.
In its expert appraisal, ANSES stresses that epidemiological studies still need to be undertaken to clarify the health effects of these employees’ working conditions and multiple exposures.
Symptoms reported by flight crew members
For several years now, flight crew members have been reporting symptoms believed to be associated with the potential contamination of aircraft cabin or cockpit air by various pollutants. These symptoms, which are highly varied and non-specific and include headaches and loss of balance, have been mentioned in several studies and grouped together under the term “aerotoxic syndrome”. ANSES’s expert appraisal confirms that the studies conducted to date do not, however, enable these symptoms to be assessed or their causes to be identified.
Various sources of cabin air pollution
ANSES notes that in aircraft cabins, multiple sources of pollution have been identified, and that these may be linked to the materials used, the operation of the aircraft and in particular the ventilation system, operations carried out on the ground and in flight, etc. In the vast majority of aircraft, the air supplying the cabin is partly bled off the engines. Compounds derived from engine oil or its thermal degradation are commonly suspected of polluting cabin air; in the literature, when this occurs, it is referred to as a fume event.
In its expert appraisal, ANSES was unable to draw any conclusions as to the origin of the pollutants detected in cabin air or their concentration levels, because the quality of the available data is insufficient.
A need for further research
To be able to assess the risks to these workers’ health, further research is therefore essential to clarify the effects on the health of flight crew members associated with their occupation and the quality of cabin air, identify the circumstances that may lead to this air becoming particularly polluted, and assess the symptoms reported by these crew members.
The Agency stresses that several research projects are under way, including:
- projects conducted in France and at European level: SPACE, at the French Radioprotection and Nuclear Safety Institute (IRSN), on mortality from cancer and non-cancerous diseases related in particular to exposure to cosmic radiation, AviSan, financed by ANSES as part of the National Research Programme for Environmental and Occupational Health (PNR EST) and conducted by a team made up of Hôtel Dieu Hospital, the French naval laboratory (LASEM) and Air France, and CAQIII, funded by the European Union Aviation Safety Agency and the European Commission and carried out by various European partners, on the potential contamination of aircraft bleed air by compounds from engine oils, hydraulic fluids and their pyrolysis products, and on the health effects of these compounds, including neurotoxicity,
- the ASHRAE 1830-RP project carried out in the United States to evaluate sensors designed to detect the contamination of aircraft bleed air by oils or hydraulic fluids.