I've been advised not put film in checked luggage. I've had no problems with carry on, but one of my students said she checked her film and it was fogged with a wild zigzag pattern that looked like a laser hit it. it was color, processed at a lab, and I suspect the film processor, but we'll never know.
Cargo and luggage scanners are very powerful and will wreck film. I know this from painful personal experience. Carry on scanners in first world counties won't. I know this from paranoid personal experience, as in I could detect no b+f increase, after no less than six scans on film 100-1600 iso. Now you could insist that the carry on scanner does something, and I couldn't argue that, but I couldn't find it with my densitometer, and I'm pretty anal about negs.
I beieve that the warning against metal objects concerrns the fact that such objects can leave a shadow. A shadow can be more troblesome than an overall amount of fog.
Remember that X-ray damage is cumulative. While a single exposure may not cause any noticeable fog, several exposures may cause trouble. It may better to buy film on location rather than bring it with you. You half the cumulative exposure this way.
The last time I flew out of Boston Logan (April 2012), there was a small sign (which I almost didn't read) warning that the X-ray scanners at *this* checkpoint (sadly, I can't remember which terminal) *were* powerful enough to fog film, and that NO film should be sent through them. I asked for and received a hand inspection of the four rolls I had in a zip-lock. Mailed the exposed rolls home from Key West.
I'm about to travel to the US and buy some film, chemistry and paper to bring over to Brazil. I always get worried about these things because it's my 6-months-worth of photography stash.
Haven't had a problem with any yet film yet, but I started to worry about paper. I understand the sensitivity of paper is far below that of film but then again it is a lot harder to carry paper as a carry-on item (anything 11x14 or bigger really won't fit a typical carry-on with out potentially damaging the paper inside).
Should I worry about sending it through checked luggage? Also, in a airport related question, has anybody had any problem checking luggage (not carry-on) with sealed B&W chemistry inside?
I did a lap of half the globe that involved 14 xrayings (carry-on) of my film, including once to get into Tiananmen Square. No effect whatsoever.
Reportedly the checked luggage scanners are higher power and I deliberately left a blank roll of Ektar in my checked luggage for a couple of flights to test that. No effect there either, but it was only Guangzhou-Melbourne-Adelaide and the both Melbourne and Guangzhou have very modern facilities and therefore probably low-power imaging scanners.
I just returned from a 2 week trip to London, Paris, and Rome. The only place I was denied a hand check for film was at St Pancras Train station in London for the Eurostar to Paris. On the other hand the airports all nicely agreed to hand check the film in my carry on bag; DFW, Paris-De Gaulle, Rome-Fiumicino, and Chicago-Ohare. :)
I had all the 120 rolls unboxed and in ziplock bags....