A survey of pilots and crew has found alarmingly high levels of illnesses they have contracted since beginning work for airlines.
One in seven of the 789 British airline staff surveyed had to take more than a month's sick leave in the previous year. One in 23 was diagnosed with cancer, even though the average age of those surveyed was around 40. According to Cancer Research, one in 34 Britons will contract cancer at some point, but for those under 44, the figure falls to one in 200.
One in 20 of those surveyed reported being diagnosed with chronic fatigue syndrome (CFS). The charity SupportME says the incidence of CFS in Britain is normally around one in 1,000. A further 20 per cent of those surveyed were diagnosed with depression - the national average is 8 to 12 per cent, according to the Mental Health Foundation.
The reports, seen by London's Telegraph, also reveal high levels of miscarriages, thyroid conditions, high blood pressure, cholesterol, pneumonia, bronchitis and IBS. Campaigners claim that the high levels of illness are the result of toxic engine fumes contaminating the air in cabins, and say this has implications for passenger safety and the health of frequent fliers.
Scientists have claimed that toxins enter the cabin as a result of the "bleed air" system used on modern aircraft. Air is drawn out of the compression section of the engine and cooled. It then enters the cabin, where it mixes with recirculated air that has passed through filters designed to remove bacteria and viruses.
These "recirculated air" filters do not remove fumes or vapours from the engine, so if engine oil or hydraulic fuel leaks, toxic chemicals can contaminate the air supply.
Sue Dale, a former airline attendant, who conducted the research in conjunction with the British Airlines Stewards and Stewardesses Association, said the results showed there was a need for a full official investigation.
Earlier this year, undercover investigators claimed to have found high levels of a dangerous toxin on several planes. Of 31 swab samples taken secretly from the aircraft cabins of popular airlines, 28 were found to contain high levels of tricresyl phosphate (TCP), an organophosphate contained in modern jet oil as an anti-wear additive, which can lead to drowsiness, respiratory problems and neurological illnesses.
Dr Mackenzie Ross, a clinical neuropsychologist at University College London, says contaminated cabin air may be affecting up to 200,000 passengers each year. A Telegraph investigation last February revealed that hundreds of incidents of contaminated air had been reported by British pilots.
Reports linking exposure to contaminated air with long-term harm to health have led to an increase in the number of passengers and crew seeking redress. This month a former American Airlines attendant, Terry Williams, 40, launched a lawsuit against Boeing over illnesses she claims were caused by toxic fumes.
A spokesman for the Civil Aviation Authority said investigations were continuing but that there was no evidence of a link between cabin air and ill health. A spokesman for British Airways said that it would continue to liaise with the authorities, including the CAA and the Department for Transport, on the issue.
The Boeing Dreamliner 787, to be launched next year, will be the first passenger jet since the mid-1950s to use air supplied from a separate source, rather than recirculated air that passes through the engine. This had previously been deemed too expensive.
What the cabin crew say
The following cabin crew, speaking on condition of anonymity, reveal the health problems they have faced since they started flying:
Case study 1 (age 36)
Illnesses: High blood pressure, high cholesterol, anaemia, pneumonia/bronchitis, asthma, infertility, chronic fatigue, insomnia, depression, multiple chemical disorder, eczema/psoriasis, IBS/Crohn's disease
"My health has become so bad over the last five years that I've only been able to work half the schedule that I used to. My doctor has attributed my illnesses to exposure to fumes and toxic chemicals on planes. I've been off work for eight months and my company has denied me compensation benefits. I'm about to lose my home."
Case study 2 (age 50)
Illnesses: High blood pressure, high cholesterol, anaemia, pneumonia/bronchitis, asthma, fibromyalgia, chronic fatigue, thyroid disorder, multiple chemical disorder, breast cancer, osteoporosis, chronic sinusitis, tachycardia, peripheral nerve damage, obstructed lungs
"I had 12 years of ill health that was a mystery until I found out about contaminated air. My GP believes all my health problems have been caused by flying and has written 'Aerotoxic Syndrome' on my medical certificate. I have been on sick leave for over a year and my airline has threatened to terminate my contract on three occasions. "
Case study 3 (age 32)
Illnesses: Pneumonia/bronchitis, osteoarthritis
"I experience extreme fatigue after flying. I have ongoing sinus problems and an increase in cold and flu and I am convinced this is related to flying . I have noticed an impairment in simple mental processes such as memory, mental arithmetic and sometimes even finding the words to speak. Before I began flying I considered myself fairly intelligent and articulate."
The Telegraph, London