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Vilhjalmur Rafnsson, M.D., Ph.D., 354-893-5415 (Iceland is 5 hours ahead
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EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, August 8, 2005

COSMIC RADIATION ASSOCIATED WITH RISK OF CATARACT IN AIRLINE PILOTS

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

Editor's Note: This study was supported by a grant from the University
of Iceland Research Fund, and the Helga Jonsdottir and Sigurlidi
Kristjansson Memorial Fund, Reykjavik, Iceland. All of the authors have
frequently traveled on Icelandair and other airline companies. They have
no financial connections with the airline company or the pilots' union.

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JAMA/Archives media relations at 312/464-JAMA (5262).