Evidence pilots, flight crews, and frequent flyers are being bombarded by radiation.
Our planet is being constantly bombarded by high speed, sub-atomic particles. These particles interact with the earth’s atmosphere and its magnetic field, generating cosmic radiation which rains down on us. The rapid depletion of the Ozone Layer, the protective layer of gases in the stratosphere that absorbs between 93-99% of the sun’s high frequency ultraviolet light increases our risk of developing the nasty “c word”. Exposure levels raise when we travel by plane, increasing exponentially at higher altitudes and latitudes.
Exposure in layman’s terms:
Airport X-ray security body scanners are generally considered safe. The National Nuclear Energy Commission  claims that the increase in cancer risk for just a dozen or so scans per year is very, very low. Although they admit it becomes significant for those having dozens of scans annually. Ironically, you will be exposed to the same dose of ionizing radiation in just two minutes of your flight once you’re at high altitude. So, one 8-hour flight is equivalent to having 240 full-body scans.
What can this do to the human body? Cosmic radiation is ionizing, which means the particles involved are energetic enough to knock charged particles from atoms, which potentially causing chemical changes in body tissue (DNA) that can increase risks from cancers and genetic abnormalities.
The risks of individuals suffering health effects as a result of being exposed to ionizing radiation of any kind, whether its from cosmic rays, a nuclear power plant, an X-ray machine, or airport full body scanner are measured in sieverts or rems (1 sievert equals 100 rems). “The same potential risks exist,” says Major Alan Hale at the US Air Force School of Aerospace Medicine, based at Wright-Patterson Air Force Base, Ohio. “Health risk assessments are based on frequency, duration, and intensity level.”
Your flight route is particularly important to consider, because the exposure rises at higher latitudes. Since cosmic radiation particles are charged, they are deflected towards both the North and the South Poles by the earth’s magnetic field lines. At these polar latitudes the magnetic field lines are closer to vertical, making it easier for cosmic ray particles to enter the atmosphere.
Airlines regularly prefer polar routes because they are shorter with lower head winds, meaning shorter flight times and lower fuel costs. Quite a few flights from the US to northern Europe and Asia pass directly over the North Pole; one good example is a flight from San Francisco to Paris. This also applies to flights from, for instance, Santiago, Chile to Sydney, Australia, which often cross over the South Pole.
In the United States, pilots, crews and flight attendants have been officially classed as “radiation workers” by the Federal Aviation Administration since 1994. Those regularly working on high-latitude flights are exposed to more radiation than workers in nuclear power plants. Despite this, the airlines don’t measure the radiation exposure of their staff; neither do they set safe limits on the doses they can safely receive.
Among flight crews, there has been a lot of research into links between cosmic radiation and health risks, especially cancer.
The available evidence suggests that those who fly occasionally have little to worry about. However, attempting to determine whether additional doses of ionizing radiation are linked to cancer and other diseases is far from straightforward and remains reason for serious concern.