Researchers are currently analyzing blood samples of almost 100 people frequently exposed to aircraft cabin air who suffer from a range of unexplained symptoms.
There are growing concerns that aircraft cabin air can become contaminated with potentially toxic chemicals and result in toxic injury and a host of symptoms, mostly neuropsychological in nature.
Now, scientists at the University of Washington, USA, are analyzing blood samples from 92 individuals, mostly pilots, cabin crew, and fequent flyers, who all suffer from from unexplained chronic illnesses which they attribute to exposure to toxic cabin air. Symptoms reported by the study participants include tremors, memory loss, poor concentration, and severe migraine headaches.
The research team, led by Clement Furlong, University of Washington Professor of Medicine and Genome Sciences, have been collecting the blood samples over the past two and a half years. According to Furlong they are only a few months away from completing blood analyses that will determine whether the study participants were indeed poisoned by toxic fumes likely to be found in aircraft cabin air.
Most passengers on the thousands of planes in the air as you read this are unlikely to give any thought to the quality of the air they are breathing but previous studies have shown it can contain a cocktail of toxic chemicals. A report published by the US National Academies of Sciences' National Research Council stated that "contaminant exposures result from the intake of chemical contaminants into the Environmental Control System and then into the cabin."
The air passengers breathe while on board a plane is a roughly 50-50 mix of filtered, recirculated air and what is known as "bleed air"; air which passes through the engines, is pressurized and cooled, then mixed with the recirculated air before being sent into the cabin through the ventilation system. It is thought this bleed air can become contaminated with chemicals including engine lubricating oils, hydraulic fluids, and deicing fluids and their degradation products. Studies have identified toxic chemicals called tricresyl phosphates, anti-wear agents in engine oil, as being of particular concern.
Furlong is quoted as stating that if the engine seals fail, there's very potent toxins that can enter the aircraft cabin.
Results of the University of Washington research could increase recognition of what a growing group of medical researchers believes is a largely ignored problem despite being described in the medical literature as far back as the 1970s, when Montgomery et al. coined the term aerotoxic syndrome to describe the symptoms suffered by pilots and flight attendants.
Last year Australia's Civil Aviation Safety Authority established a committee to examine the quality of aircraft cabin air and it's relationship to health. The Expert Panel on Aircraft Air Quality is currently examining evidence from scientific studies, individuals whose health has been affected, and industry bodies, before producing a final report in 2010 (read more).
Talking to CNN Furlong addressed the issue of why only a small percentage of pilots, cabin crew, and passengers seem to be affected by toxic fumes inhaled during flights.
He said a small percentage of people appear to be hypersensitive to the most toxic chemicals. This may be the result of genetic disposition, having abnormal expression of proteins that metabolise toxins in the liver, or from high enzyme levels (which can be triggered by prescription drugs or alcohol) that will act on the inhaled chemicals to increase their toxicity.
"If you happen to be taking a medication that turns on the protein that converts pre-toxin to very potent toxin, you've got an issue," said Furlong.
Furlong's explanation mirrors that of a small number of researchers investigating multiple chemical sensitivity (MCS), a condition in which people become hypersensitive to minute amounts of chemicals including perfume and fragranced products, cleaning and personal care products, vehicle exhaust, and cigarette smoke.
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