Danger At 40,000 Feet

Cosmic rays were once the province of science fiction, feared only by space travelers rocketing to unknown worlds. Here on earth the danger posed by streams of subatomic particles from the sun and stars was considered insignificant. Now that assurance has been shaken, at least for those who spend much of their lives flying at high altitudes. Last week the Department of Transportation reported that radiation penetrating the thin metal skins of jetliners can pose a hazard for passengers and crews.

For the occasional traveler the danger is slight and not worth worrying about. But the Government study suggests that radiation is causing a small but measurable increase in cancer rates among crew members and the most frequent flyers. As a result, the Federal Aviation Administration is sending airline workers an advisory on the health risks of cosmic radiation.

The Government estimates that among 100,000 crew members who spend 20 years on an average route, such radiation will cause 600 "premature cancer deaths." By comparison, cancer from all causes may kill 22,000 of that same group. Frequent travelers who spend half as much time in the air as pilots do, or about nine hours a week, will incur half the risk. Exposure varies dramatically with altitude and proximity to the poles. A year spent flying the great-circle route from New York City to Tokyo will subject a crew to 30 times the risk of a year of flying between Austin and Houston.

Pregnant crew members have special concerns. The FAA says women who fly throughout the first seven months of pregnancy may exceed the recommended radiation doses for fetuses and slightly boost the risk of birth defects. Some experts feel such women should consider taking leaves or working on less exposed routes, especially from the eighth to the 15th week of pregnancy. Others emphasize that the radiation is much less hazardous than other dangers of everyday life. Says Dr. Wallace Friedberg, head of radiobiology at the FAA: "If my wife was a flight attendant and pregnant, I would not tell her to stop flying."