Originally Posted by CFI2766

Chronic exposure and genetic variation are major factors as to why crew members may have a different response vs the person who flies once every 5 years.

Some interesting papers:
http://www.euro.who.int/__data/asset...yndrom_ENG.pdf

http://aerotoxic.org/wp-content/uplo...july-20141.pdf

http://www.susanmichaelis.com/pdf/Ho...ffects-%20.pdf

There is a ton of info out there on this topic. Over the past few years it has started to come into the spotlight.