not a tip appropriate for disposables, but I carry lead lined canisters that hold 4 rolls of film each. Take up less room the the boxes, not too expensive and they stop ALL kinds of nasty things. When ya get to AC, toss them in the frig, if ya have one, and film stays cool. Lead lined pouches are cheap too, I just prefer the canister
It's fun too to watch the NTSA guys at the screens trying to figure out what the hell those 5"x2.5" solid objects are.