"High humidity can promote mold growth and ferrotyping. Low humidity can create static marks when printing or cause buckling due to uneven moisture loss."
"Humidity lower than 50 % usually increases static problems and dirt attraction to processed film. At very low humidity, film curl may become a problem (e.g. Newton's Rings)."
-Kodak Storage and Handling of Unprocessed Film
http://www.kodak.com/global/en/servi...2.shtml#SEC844

I usually reload large amounts of film like a madman in multi hour sessions in the dark. Unrolling, cutting, and taping film to used cassettes from photolabs. The bulk reels (100ft, 400ft, 1000ft) are thawed to room temp and opened in relative humidity of a dry household bathroom, reloaded and repacked into the plastic canisters. Those canisters get bagged with a ziplock + silica gel packet and thrown back into the fridge. So far it has been perfectly fine. I would avoid bagging open (not plastic cased) cassettes with silica gel or rice, due to the fact that they might absorb too much moisture from the film when in storage for a period of time.

Off topic but: Sometimes when the humidity is a bit low, like in winter, its pretty awesome to rip off the tape on one of the bigger reels, as sparks shoot out in the pitch black room. Scared me the first time as I worried about the film, but realized it was safe in the metal tin. Its also a sign that says to unload the film in the bag a bit slower so sparks dont shoot off the reel from the static (like when your quickly pulling 36exp arm lengths).