that is very true exposure risk is greater the higher you fly. Also an issue is that during a fire the depleted uranium that they use for ballast is very nasty. oxidises very hot and if inhaled does all sorts of damage.
All of the rad stuff is very subjective because it only adds to the enviroments dose so its very hard to prove that the additional dose is the cause of any problems.
BNFL still dosn't admit libality for anyone getting cancer but they do have a compensation scheme if you don't follow legal process.
I used to be a registered rad worker who had to carry a film badge. Its a personal descision if you are willing to take the addition risks involved. For myself it is worth it. The chaps who get the real big stuff are the concorde pilots and mil pilots, under the tropause it is an acceptable risk (in my opinion)
MJ