Aerotoxic Syndrome

Tricresyl phosphate (TCP), and in particular its tri-ortho substituted isomer (o,o,o-TCP), has been frequently used in aircraft engine oil. Bleed air, provided to the flight deck and cabin can contain traces of TCP. TCP can cause neurotoxic effects in humans. Regularly, airline pilots complain about loss of memory , headaches, dizziness, tunnel vision and other neurotoxic effects. The concentrations of TCP reported in flight deck air (max. ca. 50–100 ng m À3 total TCP) do not exceed provisional toxicity thresholds. These thresholds, however, contain a very high uncertainty and need further underpinning. The many non-detects and relatively low TCP concentrations reported suggest that TCP on its own is not likely to be responsible for the reported health problems of pilots. Specific conditions in air planes and other toxic compounds present in bleed air, whether or not in combination with TCP, may be responsible for the reported neurotoxic syndromes. Sensitivity of individuals seems to be an important factor as well. The clinical signs observed with a selected group of pilots are serious enough to call for further elucidation of this issue.

Summary (Foreword)
While investigating and researching the issue of contaminated cabin air since 2008 I have personally met more than some hundred individuals who all have one thing in common: they became victim to toxins present in the cabin air aboard modern aircraft and they became seriously injured. This, in most cases, changed their lives forever. One of them was Bearnairdine Beaumont, a former chief flight attendant and the author of this book. While industry representatives, and among those even professionals, who claim to have a profound medical background, are still denying that these symptoms may be associated with anything these people inhaled aboard any aircraft, there is overwhelming evidence to the contrary. (Tim van Beveren)

This paper assesses the current status of the diagnosis “aerotoxic syndrome”, namely, the
cluster of characteristic symptoms reported after exposure to aviation engine oil fumes. The
review begins with a short history of the diagnostic term since its introduction in 2000, and
describes how the onset and characteristics of the reported symptoms are distinct from other
medical conditions. While there is obvious overlap between aerotoxic syndrome and multiple
chemical sensitivity, the former should not be considered a subcategory of the latter. A
“nocebo effect” does not adequately explain the prevalence and consistency of the
symptoms that continue to be widely reported by individuals exposed to engine oil fumes on
aircraft. Currently, occupational and aviation medicine specialists largely rely on a diverse
collection of diagnoses describing their patients’ neuropsychological deficits, as well as
neurological, respiratory and cardiac abnormalities, among others. There is merit in a single
diagnostic descriptor capturing these symptoms.

Aero-Toxic Syndrome is more then a “phrase” invented by Harry Hoffman, Chris Winder and Jean Christophe Balouet in 1999, to describe a number of short and long term ill-health effects caused by being subjected to cabin air alleged to have been contaminated to toxic levels by atomized engine oils or other chemicals. Inhalation is, however, only the tip of the transfer ice berg, which also consists of skin deposition, skin penetration, pore manipulation through electrostatic forces and discharges caused by elevated or wrongly directed electric fields. This happens also close to the skin propagating in that way the chemical kaleidoscope covering the crew’s uniforms.  All this, when investigated in the context of Traditional Chinese Medicine, shows that the used term "syndrome" is indeed the right one. The mentioned atomization, is likely a far too simple approach when it comes to the behavior of the synthesized oil and chemical vapors  released in the hostile environment present in the aircraft jets and which, after various treatments, is send to the cabin as clean "bleed air". The symptoms caused by the Aero - Toxicity Syndrome seems for many, like the National Research Council (NRC) to be “broad and nonspecific”.  Their review is based mainly on cabin Temperature and Pressure, and they recommends to add eventually: O3, CO, CO2, and RH. When it comes to the real “suspects”: Phosphor, Sulfur, Hydro Carbons, Bio and Aerosol particles, the instruments necessary to measure them are for the Council [1]: either “not suited”, or “not yet available” or “too expensive”. A stalemate affecting the health of crews and passengers world wide.

Cabin crew, pilots and passengers increasingly experience a range of flight safety and health problems resulting from the uncontrolled emission of unfiltered and recycled toxic chemical fumes from a mixture of jet oils, kerosene and carbon monoxide in to the cabin breathing air.

Some aircrew members affected by bleed-air fumes report "epileptic" type symptoms after exposure. Seizures (aka “epileptic type” or similar to) are generally regarded as a manifestation of carbon monoxide poisoning. A case is described in which a seizure attributable to carbon monoxide poisoning occurred in a small child at a level not thought to be associated with serious neurological toxicity. (very low-level)

When toxins are released into the environment by any other industry, or when toxic fumes are detected in public buildings, trained professionals in hazmat suits instantly crawl all over the hastily closed-off sites in question, testing the air taking samples with specialised equipment.

Not so in aviation. Toxic gas-type fume emissions occur daily in aircraft. This kind of scenario is happening regularly worldwide and is the aviation industry’s sore spot. Escaping engine oil fumes can cause pilots and cabin crews to become incapacitated and unable to function. Increasingly passengers are also overcome by these physically harmful noxious fumes.

The rise in incidences points the finger at airlines’ negligence concerning safety procedures and required maintenance protocols of their aircraft, not to mention the pressure they put on their employees to ignore and not report. The aviation industry seems to think it is safe and acceptable to breathe these harmful fumes in a confined space.

In this article the author attempts to explain the possible adverse health effects on humans that can result from exposure to and inhalation of ultrafine toxic particles, in particular after inhalation of jet-engine oil fumes/smoke on aircraft.
The air enters the aircraft cabin unfiltered. If the engine seals are worn or fail completley or if the engines are improperly serviced (e.g.overfilled/overserviced with oil, as has been stated to be the possible reason in a recent fume event on an Airbus 388) oil fumes or smoke/mist may enter the cabin. Disturbingly, it seems that certain engine seals appear to allow some leakage of oil into the bleed air system even under normal operating conditions due to (faulty?) manufacturing.