I would imagine it's because of the increased radiation you receive during a flight. For one flight, it's negligible, but if it's your job to be in the stratosphere for 20+ hours a shift, year round, it will probably start to add up. It would be like spending all your work life on the beach.
> It would be like spending all your work life on the beach.
This is where flight attendants spend their non-work life :-)
The radiation from the flight could be a factor of course; but being from Norway myself, and getting burned like a cooked lobster every time I go to Spain etc. I can't imagine that stuff being healthy to do regularly (or perhaps at all).
