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(dated 7 July 2004). It can be down-loaded from CAMI’s website or accessed on-line at
http://jag.cami.jccbi.gov./cariprofile.asp. A similar European programme, EPCARD (European Program
Package for the Calculation of Aviation Route Doses), has been developed and is available on-line in
English and German at www.gsf.de/epcard2/index.phtml.
Risk Assessment
Ionization can cause chemical changes in living tissue and may thus affect the behaviour of living cells.
This can lead to cell death (as in acute radiation sickness) or to alteration of genetic material within the
cell (so-called mutation as seen in late sequels). The latter can induce cancer or lead to anatomical defects
in a foetus. These effects, however, are dose related: low doses of radiation carry a low risk, and the lower
the radiation dose is, the longer is the interval from exposure to development of disease, often many
years.
We have no exact knowledge about the risk of low dose radiation, but studies of the survivors from
the Hiroshima and Nagasaki atomic bombings in 1945 indicate that a radiation dose of 500 mSv leads to
development of cancer in about 1% of those exposed. Consequently, according to the theory of linearity, a
radiation dose of 1 mSv entails a cancer risk of 0.002% (1 mSv is about 1/3 of the natural background
radiation, vide supra). With few exceptions the incidence of cancer has not been increased detectably by
doses of less than 100 mSv.
It is generally estimated that 1.5% of all fatal cancers in the general population result from natural
background ionizing radiation. A man, living on Earth for 70 years, will receive a total dose of ionizing
radiation of about 210 mSv. His risk of developing a cancer due to radiation is about 0.42% or one in 238.
If he flies as an airline pilot for 40 years he may receive an additional dose of some 112 mSv which
entails an additional cancer risk of about 0.22%. The over-all risk of acquiring a fatal cancer disease (all
types, all causes) during a lifetime is about 22% (including 0.42% caused by radiation). The airman’s
total risk will thus rise from about 22% to about 22.2%. In other words: if one thousand airmen have a
normal flying career, the expectation is that two of them would eventually die of cancer as a result of
occupational exposure to radiation. Based on normal expectation for the adult population, about an
ICAO Preliminary Unedited Version — October 2008 II-1-14
additional 220 of the 1000 airmen would die of cancer from causes unrelated to occupational radiation
exposure. There is, of course, no way of telling whether a specific cancer is caused by background
radiation, occupational radiation or other factors.
A liveborn child conceived after radiation exposure of its parents is at risk of inheriting a genetic
defect that may lead to a serious health impairment. From each parent’s exposure, the risk coefficient is
1.5 in 1 000 000 per mSv. If a female crewmember works for ten years and thus is exposed to an
additional 28 mSv, the risk to the child as a result of work related exposure to radiation would be
approximately 28 x 1.5 = 42 in 1 000 000. In the general population about 6% (or 60 000 in 1 000 000) of
the children are born with anomalies that have serious health consequences. In other words: if 23 800
children were born after occupational radiation exposure of their mothers, one of them would have a
congenital genetic defect or eventually develop a genetic disease as a result of his mother’s occupational
exposure to radiation. Based on the normal expectation for newborn children, an additional 1428 children
of the 23 800 would have genetic defects from other causes.
Recommendations
In view of the fact that ionizing radiation is now assumed to play a role in mutagenic or carcinogenic
activity, any procedure involving radiation exposure is considered to entail some degree of risk. At the
same time, however, the radiation-induced risks associated with flying are very small in comparison with
other risks encountered in daily life. Nevertheless such risks are not necessarily acceptable if they can be
easily avoided.
Theoretically, the radiation exposure in air crew can be reduced by optimizing flight routes and crew
scheduling, and by installation of radiation warning devices5. Such devices are particularly effective in
detecting high momentary radiation during solar flares and can thus be used in determining a need for a
lower cruising level. Female crew members should be aware of the possible risk to the foetus and should
be scheduled in such a way as to minimize the exposure during pregnancy.
Much study has been directed to the potential hazards of cosmic radiation (CR) to flight crews and
passengers of supersonic transport (SST) aircraft. Measurements show that in the high latitudes above
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Manual of Civil Aviation Medicine 1(63)
