Anybody interested in calculating cosmic radiation during a flight check this site:
deutsch
www.gsf.de/epcard/deu_start.php
english
www.gsf.de/epcard/eng_start.php
Result comes in microSievert. As far as I know, maximum for
a worker in a nuclear power plant is 20 milliSievert a year or
400 milliSievert during a lifetime.
Watch your altitude around the poles !