Researchers say they've determined airline pilots are at increased risk of cataracts usually associated with aging as a result of cosmic radiation. Commercial airline pilots previously were reported to be at increased risk for some cancers, but studies on the biological effects of cosmic radiation exposure were limited, according to the researchers.
Dr. Vilhjalmur Rafnsson of the University of Iceland and his colleagues conducted a case control study involving 445 men to determine whether employment as a pilot is associated with lens opacification.
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.
"The odds ratio for nuclear cataract risk among cases and controls was 3.02 for pilots compared with non-pilots, adjusted for age, smoking status, and sunbathing habits," the researchers reported, reports Science Daily.
Dr Larry Benjamin from the Royal College of Ophthalmologists said to BBC News, that cosmic radiation and other wavelengths such as UV light might potentially damage proteins in the lens of the eye.
"It damages cell repair mechanisms and probably also causes the protein in the lens to cross link. Sort of like cooking an egg and the egg goes white. Once that has happened it is irreversible."
However, he said cataracts were easy to treat with surgery.
But Dr Michael Clark from the Health Protection Agency said it was unlikely that cosmic radiation was the cause of the pilots' cataracts.
"Pilots and aircrew receive doses that are two or three times normal background in a year, primarily from cosmic rays.
"This is well within the range of variations in background doses at ground level so we would not expect to see any health effects.
"On current evidence, it seems unlikely that cosmic rays could be the cause of cataracts in pilots, but this finding is bound to stimulate more research in this area."