Flight crews on commercial airlines receive up to four times the radiation dose experienced by the typical nuclear plant worker, a conference in Dublin has heard.
A three-day international conference on flight crew exposure to naturally occurring cosmic radiation opened yesterday with an address by the Minister of State with responsibility for nuclear safety, Mr Joe Jacob.
A new EU directive on occupational exposure to natural radiation had been introduced, he said, which would require the aviation industry and national regulators to review existing controls for the protection of flight staff, particularly women working during pregnancy. The directive must take effect by May 2000.
"The additional safety requirements for radiation protection of air crews will undoubtedly have financial consequences," he said. "It is our intention to prepare a consultation paper in the next few months on how Ireland proposes to implement the directive."
The directive sets an action limit for radiation of one millisievert a year - the limit for members of the general public and equivalent to about 50 chest Xrays. Crew exposures above that would require the introduction of counter-measures such as adjustment of working schedules.
The conference, at Trinity College, was organised by the European Commission and the Radiological Protection Institute of Ireland. It brings together scientists, aircraft manufacturers and groups representing pilots and cabin staff. The main points of discussion are the directive and how radiation exposures can be reduced.
Cosmic radiation is given off by the sun and by bodies further out in space. It bombards the earth, delivering ionising radiation which, at high altitudes, can deliver a measurable dose to crews and passengers. The higher the aircraft the greater the exposure, explained Dr David Bartlett of the UK's National Radiological Protection Board.
Crews on Concord received about twice as much radiation per hour as crews working aircraft flying at lower altitudes of about five or six miles, he said. The radiation worker at a nuclear plant might typically receive a radiation dose of one millisievert per year, but flight crews experience at least double that and up to four times as much.
"The aim of the directive is to bring air crews into the same regulatory framework as other radiation workers," Dr Bartlett said.
While a female cabin attendant would have exposure measured like a radiation worker, if pregnant her foetus would be considered a "member of the public", and so the one millisievert level would apply. Dr Maria Blettner of the International Agency for Research on Cancer in France said there had been few studies of cancers and deaths among flight crews. This made assessments of the health risk associated with flying very difficult.
"Very little is known about specific occupational risks" for these workers, she said. It was also difficult to separate risks linked to cosmic radiation and the contributory aspects of air crew stress, lifestyle and exposure to engine exhaust gases and strong electromagnetic fields.
Capt Andrew Tisdall of the Irish and the International Airline Pilots' Associations told The Irish Times that flight crews were "nervous" about the implications of radiation exposure. "Some believe they are being kept in the dark." No data had been presented yet showing there was a hazard.
