Cosmic Radiation Associated With Risk Of Cataract In Airline Pilots

Commercial airline pilots are reported to be at an increased riskfor some cancers, but studies on the biological effects of theirexposure to cosmic radiation have been limited, according to backgroundinformation in the article. Previous studies have shown that cataractscan be caused by exposure to radiation, including a recent study ofastronauts showing an association of incidence of cataracts with spaceradiation at exposure levels comparable to those of commercial airlinepilots.

Vilhjalmur Rafnsson, M.D., Ph.D., of the University of Iceland,Reykjavik, and colleagues conducted a case control study involved 445men to determine whether employment as a pilot is associated with lensopacification. The cases included 71 men with nuclear cataract, and thecontrols (n = 374) were those men with different types of lensopacification or without lens opacification. Among the 445 men, 79 werecommercial pilots and 366 had never been pilots. All participants inthe study were 50 years or older and other factors that contribute tocataract risk, including smoking, age and sunbathing, were controlledfor in the statistical analysis. Exposure to cosmic radiation wasassessed based on employment time as pilots, annual number of hoursflown on each aircraft type, time tables, flight profiles andindividual cumulative radiation doses calculated by computer.

Among the 71 cases with nuclear cataract, 15 were employed ascommercial pilots, whereas among the 374 controls (without nuclearcataract), 64 were employed as pilots.

"The odds ratio for nuclear cataract risk among cases andcontrols was 3.02 for pilots compared with nonpilots, adjusted for age,smoking status, and sunbathing habits," the researchers report. Theresearchers found an association between the estimated cumulativeradiation dose and the risk of nuclear cataract.

"The association between the cosmic radiation exposure ofpilots and the risk of nuclear cataracts, adjusted for age, smokingstatus, and sunbathing habits, indicates that cosmic radiation may be acausative factor in nuclear cataracts among commercial airline pilots,"the authors conclude.

(Arch Ophthalmol. 2005; 123:1102-1105. Available pre-embargo to the media at www.jamamedia.org.)

Editor's Note: This study was supported by a grant from theUniversity of Iceland Research Fund, and the Helga Jonsdottir andSigurlidi Kristjansson Memorial Fund, Reykjavik, Iceland. All of theauthors have frequently traveled on Icelandair and other airlinecompanies. They have no financial connections with the airline companyor the pilots' union.