Evidence is growing of a possible link between cosmic radiation and cancers among aircrew

DeeDee Doke/OXFORD

The May deadline is approaching for European Union countries and airlines to start taking stock of the cosmic radiation aircrews are exposed to when they fly.

In a recent medical study of instances of cancer among aircrew, a Danish team found "increased risks of acute myeloid leukaemia and total cancer" among Danish male jet cockpit crew members flying more than 5,000h. The researchers concluded in their report - published in The Lancet medical journal on 11 December, 1999 - that the finding "could be related" to cosmic radiation, or radiation originating outside the Earth's atmosphere, which has greater effect as altitude increases.

Other studies have shown that pilots experience higher mortality rates from some cancers than the general population.

EU countries appear to be approaching the finishing line for legislation to enforce the European requirements that were set in motion in May 1996 (see box). The UK Government, for example, is considering the imposition of a maximum fine of £5,000 ($8,200) for failing to comply with the requirements. The proposal also calls for two years' imprisonment and/or a fine on indictment.

Airlines, for the most part, are waiting to view the laws to be enacted by their home countries and, in some cases, are joining other carriers to develop a unified approach to the requirements.

"At the moment, no records are kept. No one is pinpointing anything," says Farrol Kahn, director of the Aviation Health Institute, a UK medical research charity that promotes health and wellbeing for flyers worldwide.

But Hans Lebuser, a retired Lufthansa pilot who heads the German Cockpit Association's working group on cosmic radiation, thinks otherwise. Following the Chernobyl nuclear reactor disaster in 1986, Lufthansa pilots "were kind of afraid of flying through a radiation cloud", he says. Small radiation detectors were put on board, and although they provided no useful data on Chernobyl radiation, "we realised that there was other radiation going on", adds Lebuser. "When we'd reach cruising altitude, the small detector started ticking like crazy. We decided to take a deeper look."

Since then, the German pilots have been key advocates for more in-depth studies of cosmic radiation and its health effects. Lufthansa is recognised as one of the most proactive airlines for conducting research and informing aircrews and "on request, any other persons concerned" as to the risks of cosmic radiation.

Barbara Reck of the airline's environmental issues department says an epidemiological study of all crew members employed by Lufthansa since 1960 - about 25,000 people - is under way, and the results will be available by the end of the year. The number of people involved means that the study "will be much broader and provide more information than any other previous one", says Reck.

The airline has also formed a special working group on cosmic radiation with other members of the Association of European Airlines, to develop a harmonised approach to the EU requirements that take effect in May. "It was, for instance, agreed that in daily routine, dose assessment will be done by calculations using appropriate computer models and that, in addition, single verification measurements might be performed," says Reck.

Lebuser would like the airline to go further and consider measures to reduce aircrews' potential exposure to cosmic radiation, such as flying at lower altitudes (the amount of radiation increases significantly above 30,000ft (9,150m), avoiding polar routes which also increase exposure, adopting more southerly routes, and adding staff so that crew members fly less. Such measures are expensive, he says.

Reck says, however, that the airline is distributing its routes among staff so that each has a mix of long- and short-haul flights. Longer flights expose crews to greater radiation. A US expert says, for example, that flying at 37,000ft for 4.1h is equivalent to having a full chest X-ray.

Civil liability for employees or passengers appears unlikely to become an issue at present, suggests solicitor Patrick Slomski of London's Beaumont and Son. "You can make an allegation, but it's a question of what you can prove," he says. "In my view, at present, it would be extremely difficult to demonstrate a causal link between so many hours of flying and illness."

But Richard Hillick, director of Scotland-based safety consultants Sage Safety, who has advised civil and military interests on nuclear matters, urges the aerospace and aviation industry to learn from the nuclear experience. He says that openness, agreeing on procedures to determine the cost of safety and compensation schemes for certain levels of radiation would help temper the public's perception of potential dangers and deal with a "political imperative".

"Agreed procedures should be formed before cosmic radiation is considered to be a problem," says Hillick, "starting with putting a cost on the price of safety. We're very much interested in this whole question: how much money does it take to make something a little bit safer?"

Once a crisis develops, says Hillick, "this becomes a highly emotive issue". He points out that statements made in the immediate wake of the Paddington rail crash in the UK in October 1999 suggested that no price was too high to save a human life, but several months later, when high emotions have cooled, practical financial considerations again weigh in on funding expensive safety improvements.

"These things need to be discussed up front," says Hillick. "The airlines should be thinking about establishing arguments for and against changing their flying practices. It will be far easier for them if they are working in unison and they've agreed with the unions how to treat this."

The ideal would be for airframe manufacturers to develop an aircraft that flies at lower altitudes without sacrificing fuel efficiency so that airlines would not suffer financially by seeking to protect their crews from unnecessary risks. Because this prospect appears unlikely for the time being, Germany's Lebuser favours legislation to make airlines reduce flight lengths so that all must compete on the same, less advantageous financial basis.

Although some authorities contend that a definitive link has yet to be made between cosmic radiation and health risks, the Aviation Health Institute's Kahn predicts that more evidence is about to emerge of the potential hazards to aircrews and frequent fliers. The era of widebodied aircraft is entering its 30th year, which would make the time ripe for some cancers with a 20 to 25-year gestation period to manifest themselves.

"The scene is set," says Kahn. "There is more to come."

Source: Flight International