Copyright © 2001 The International Herald Tribune | www.iht.com
IHT EXCLUSIVE Flying on Top of the World: A Radiation Risk
Thomas Crampton International Herald Tribune
Wednesday, May 23, 2001
HONG KONG Passengers and crew members flying on the recently inaugurated North Pole route between New York and Hong Kong are exposed to unusually high levels of cosmic and solar radiation, according to international experts, provoking concern among airline unions and scientists.
Passengers taking five round trips on the nonstop route could exceed maximum recommended levels for annual radiation doses that are set for the general population by the European Union and the Stockholm-based International Commission on Radiological Protection, according to three scientists who have studied the issue individually.
"A frequent flying executive who recently became pregnant should really think twice about flying this polar route," said Ian McAulay, a professor of experimental physics at Trinity College in Dublin, who helped draft the European Union's guidelines for in-flight radiation. "It would also be very useful for all frequent fliers to be informed about the risks."
The two airlines already using the transpolar route, which was inaugurated in March, have each rerouted at least two flights to more southerly paths to reduce radiation exposure. One, Continental Airlines, cited concern over passengers' health as the primary reason. The other, United Airlines, said it had acted to limit radio interference from solar radiation.
Any air travel involves greater exposure to cosmic and solar radiation than staying on the ground. That is because the air is thinner at high altitudes and provides less protection against the radiation that constantly bombards Earth from space.
The New York-Hong Kong flights involve even more exposure, scientists say, in large part because of higher radiation levels resulting from the magnetic attraction that the North Pole exerts on charged radioactive particles from space.
Continental, United and Cathay Pacific Airways, which plans to inaugurate its route in September, acknowledge that passengers on the route are subject to higher radiation exposure. But they say the health risk is very small.
"Under normal conditions, I do not think there is any greater health risk flying this route than any other route," said Gene Cameron, manager of international dispatch for United Airlines.
He added, however, that, during major solar storms, which produce flares releasing large radiation bursts, "I think we would have to relook at it, because you are getting more radiation than you would normally be subjected to."
Scientists and airline employees unions, who have raised the issue in the past, have expressed concern, especially for pregnant women and frequent travelers.
"The way they operate this transpolar route yet again demonstrates the airlines' consistent disregard for the health and comfort of passengers and crew," said Shane Enright, spokesman for the International Transport Workers' Federation Civil Aviation Section, which represents 600,000 aviation workers at almost every major airline and airport in the world. "At the very least, the airlines should inform pregnant passengers and frequent fliers of the radiation risks associated with the route."
A pilot from one airline who requested anonymity said that captains had recently started insisting on flying at lower than optimal flight altitudes along this and other routes to avoid excess radiation exposure.
Robert Barish, a New York health physicist who specializes in studying in-flight radiation and has written a book on the subject, reckons that the dosage received during each flight along the transpolar route is equivalent to three chest X-rays and may be significantly increased by solar flare radiation.
A standard one-way trans-Atlantic flight between New York and London exposes fliers to the equivalent of less than two chest X-rays, Mr. Barish said.
With the Hong Kong-New York flight prominently promoted on buses and billboards in Hong Kong, some investment bankers already fly the route several times a month. Both airlines now operating the route say their customers include a high proportion of business and first-class frequent fliers.
"It is these frequent flying elite business travelers and crew who should be informed of the increased dosage of radiation on this route," said Martha Waters, a research scientist at the U.S. government's Centers for Disease Control. "The occasional flying general public need not be too concerned on this issue."
The dose of in-flight radiation for each one way transpolar flight from New York to Hong Kong could reach 0.10 millisievert, a standard measure of radiation exposure, even without additional radiation from a solar flare, according to calculations made by Ms. Waters using the U.S. Federal Aviation Administration's CARI-6 computer program.
According to Ms. Water's calculations, a passenger taking no other flights than one return trip on the route every other month could surpass the maximum dosage guideline of one millisievert per year set for the general public by the EU and the Radiological Protection agency.
Calculating separately and independently, Mr. McAulay and Mr. Barish affirmed that radiation from five round-trip flights could surpass the threshold of one millisievert.
United and Continental declined to provide their own estimates for exposure to cosmic radiation along the route.
While the annual exposure threshold of one millisievert has no particular radiobiological significance, it was set up by the International Commission on Radiological Protection to develop practical restrictions on public exposure to radiation. Dosage limits for those exposed to occupational radiation in the course of their work, such as nuclear power plant workers, are set at 20 times that level in Europe and 50 times that level in the United States.
Heavy doses of radiation can cause damage to a developing fetus, provoke cancer or produce genetic mutations in human egg and sperm cells. In addition, the neutron-intensive radiation experienced in flight is more damaging to cell structure than X-rays, Ms. Waters said.
A European directive on in-flight radiation, which took effect in May 2000, requires airlines to track radiation dosages received by air crew members and to inform them when they breach the level of one millisievert.
Crew members are then temporarily rescheduled to fly on shorter, lower-radiation routes. On declaration of pregnancy, a crew member must immediately switch to low-exposure flights, and some European airlines go further and ground expectant mothers until after maternity leave.
The U.S. Federal Aviation Administration recommends that airlines inform their flight crews of the risks associated with long-haul flights at high latitudes.
Mr. McAulay said, "The radiation on one flight may not be an immediate health hazard but it is important that air captains, first officers and frequent travelers know about the risks.
The airlines flying the North Pole route said they do not inform passengers of the increased cosmic radiation risks. But they said they take precautionary measures, such as monitoring for solar storms.
Sarah Anthony, a spokeswoman for Continental Airlines, said: "Our job is to operate the flight, so we cannot advise people on medical needs. That is not what we do. That is not our business."
United Airlines said: "Though health risks associated with exposures to higher levels of cosmic radiation are very small, pregnant women who are planning to travel on long-haul flights should be informed on the issue."
Referring to the instances when Continental and United rerouted flights to avoid unusually high levels of radiation, spokesmen for the airlines said they did not know what the captains had told passengers about the reason for the change.
Cathay Pacific said it has joined a group set up by Hong Kong's civil aviation authorities specifically to control exposure to in-flight cosmic radiation.
Research into the radiation risks of long-haul, high- altitude flights remains in its infancy, but several cancer studies among pilots have found increases in certain cancers often associated with radiation.
A 1996 paper published in the American Journal of Epidemiology found a higher incidence of myeloid leukemia, astrocytoma, prostate cancer and malignant melanoma among 2,740 Air Canada pilots than in the general population.
One study of female flight attendants in Finland and Denmark found an increased rate of breast cancer.
Anecdotal reports of high rates of miscarriage and menstrual disorders among flight attendants have prompted the U.S. government's Centers for Disease Control to start a broad-based study on the impact of in-flight radiation due for completion this year. Another large-scale study, on cancer rates among flight crews, will be completed this summer by the Radiation Protection Commission in Germany. Early reports of preliminary findings suggest that flight attendants have breast cancer rates twice those of the general population and that their skin cancer rates may be 15 times as high.
Copyright © 2001 The International Herald Tribune