Cosmic radiation associated with risk of cataract in airline pilots

Airline pilots have an increased risk of nuclear cataracts [common type of cataract, associated with aging] compared with non-pilots, and that risk is associated with cumulative exposure to cosmic radiation, according to a study in the August issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

Commercial airline pilots are reported to be at an increased risk for some cancers, but studies on the biological effects of their exposure to cosmic radiation have been limited, according to background information in the article. Previous studies have shown that cataracts can be caused by exposure to radiation, including a recent study of astronauts showing an association of incidence of cataracts with space radiation at exposure levels comparable to those of commercial airline pilots.

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

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

“The odds ratio for nuclear cataract risk among cases and controls was 3.02 for pilots compared with nonpilots, adjusted for age, smoking status, and sunbathing habits,” the researchers report. The researchers found an association between the estimated cumulative radiation dose and the risk of nuclear cataract.

“The association between the cosmic radiation exposure of pilots and the risk of nuclear cataracts, adjusted for age, smoking status, and sunbathing habits, indicates that cosmic radiation may be a causative factor in nuclear cataracts among commercial airline pilots,” the authors conclude.