Health Effects of Contaminants in Aircraft Cabin Air
Professor Michael Bagshaw MB BCh MRCS FFOM DAvMed DFFP FRAeS
Summary Report, Version 2.6
Latest version (October 2013)
Full paper here:
https://www.airpilots.org/file/1277/...ort-oct-13.pdf
CONCLUSION
There has been an increase in reported incidents of in-flight smoke/fume events since 1999, with a small number of crew members reporting adverse health effects which they associate with the events.
The source of oil contamination of engine bleed air was identified in early versions of the BAe 146 and the Boeing 757 and suitable modifications were implemented. A range of chronic health effects continue to be reported by some crew members.
The toxic effects of organophosphates are specific and are due to impairment of neurotransmission in the peripheral nerves, giving rise to muscular weakness and paralysis. In terms of medical toxicology, it is impossible to explain the wide range of symptoms and signs reported by some crew members as a unified result of TCP exposure.
Symptoms reported by some crew members who have been exposed to fumes in the cabin, particularly when emergency oxygen masks are used, are the same as those seen in acute or chronic hyperventilation. Obviously not every case of ‘aerotoxic syndrome’ is caused by hyperventilation, but it offers a plausible explanation for some reported events.
In some cases, the symptoms may be due to irritation associated with enhanced chemical sensitivity to certain volatile organic compounds.
The reported symptoms are wide-ranging with insufficient consistency to justify the establishment of a medical syndrome. It has been noted that many of the acute symptoms are normal symptoms experienced by most people frequently; some 70% of the population experience one or more of them on any given day.
Individuals can vary in their response to potential toxic insult because of age, health status, previous exposure or genetic differences.
In addition, it can be difficult to disentangle the physical, psychological and emotional components of well-being, and there is no doubt that different people will respond in different ways on different occasions.
It is not understood why most occupants of pressurised aircraft do not report symptoms despite having the same exposure as those who do.
Finally, so far as scientific evidence has been able to establish to date, the amounts of organophosphates to which aircraft crew members could be exposed, even over multiple, long-term exposures, are insufficient to produce neurotoxicity.
Investigations of aircraft cabin air world-wide have failed to detect levels of TCP above well-established and validated occupational exposure limit values. The partial pressure in the alveolar gas mixture of any TCP contamination of the cabin air is so low that it is unlikely to cross the alveolar membrane.
Genetic or particular susceptibility to a particular adverse effect of certain chemicals on the part of an individual does not alter the need for there to have been a sufficient chemical exposure to cause the injury or damage. For the reasons set out above, the possible exposure levels to ToCP on aircraft are so low relative to what is required to create a toxic effect through inhalation that a toxic injury is simply not medically feasible with current understanding.
Aviation medical professionals throughout the world continue to monitor the scientific evidence and remain receptive to objective peer-reviewed evidence.