It's generally forgotten that ensuring the machines are safe for films also means they are very much safer for the human operatives. At one time only men, and women over child bearing age, were allowed to operate the carry on scanning machines.
Can someone confirm if the film has been tested with a densitometer?
I had some 400 speed HP5+ that I took overseas, someone in my camera club has a densitometer and he said the film has more fog than normal. Not sure if this was b/c I had film that was some yrs old or if it was xray related however you can still get nice prints off them. Off the same person he showed a person about fog when you use the fixer too many times but still adhering to Ilfrord's recommendation. He now uses 1L of working solution of fix for 6 rolls.
Nobody at any airport in Canada / Victoria BC and Alaska agreed to hand-checking of my sister's carry-on kit that included one old AF compact film camera. I gave her a roll of Provia 400X and two of Provia 100F; none were affected despite having passed through a total of 16 X-ray inspection points over 4 weeks (including ports visited by the MS Zuiderdam) (!). However, two SD cards for brother-in-law's digi camera were corrupted and we had to contact the photo store in Victoria BC to get copies of the files posted to us (she'd gone there to have "postcards" printed from the card). So... a positive reinforcement for film that has come through shining, but a question mark on the security of SD cards.
Now, I think it would be very fair to say that Customs around the world are aware of the concerns of film photographers and they are up to date with knowledge as to how safe that film is passing through X-rays. I cannot see anything happening that would cause a catastrophe unless you are running through Delta P3200, which I know will fog after 2 passes — and Customs do acknowledge the risk of X-rays to high speed film, so hold it up to them. No harm in asking for a hand inspection but I doubt you will, or should be afforded, one given that you could potentially be holding up a queue of impatient and irritable people. :)
I took 100 rolls of Neopan 100 (120), and 200 sheets of TXP320 (5x4") - Melbourne-Sydney-Tokyo-Frankfurt-Berlin, then Zürich-Hong Kong-Sydney-Melbourne last year, and couldn't find a trace of fogging in anything. I brought back another ten rolls of TMAX400 from Tokyo (the weather was a bit dark at times for Neopan), and that was fine too. At most, that's 7 journeys through carry-on x-ray without anything that would impact on printing when I got back home. I think it's fair to say I will never bother with the HASSLE of hand-inspection...
I based this on what the government tells us - that film is safe to iso 800. Is it unreasonable then to assume then that 1600 is possibly unsafe? In that case, a 2nd exposure could cause fog on iso 800 film. 2 more exposures could affect iso 400, another 4 could affect iso 200, and so on. I hate to do this, but have to ask for a citation for the comparative levels of exposure in flight vs xray.
Color negative film
The results of this test showed that banding (uneven density areas) was noticed after 25
passes with ISO 400 color negative film, and after 10 passes with ISO 800 color negative
film. Prints were made from the ISO 400 film, and it was noticed that there was only a
minimal color shift through the scan sequences. Also there was loss of contrast, and an
increase in granularity starting at pass 10 and increased as the number of scans increased.
This was especially noticeable in the under exposed frames. In each case the base fog
(density of the unexposed areas) increased with the number of passes. The density of the
exposed areas increased as well, but in smaller amounts.
Black and White film
An uneven fog pattern was noticed, especially with ISO 3200 film between 1 and 5 passes. At 25 passes this effect was extreme.
Oh... and here are the industry study recommendations to the governments:
Based on the testing completed at the FAA Technical Center in Atlantic City, I3A
recommends a limit of five passes through the carry-on baggage security check point
systems for all color negative and reversal film, including single-use cameras, up to and
including ISO 800 speed film. While in some cases it may take a greater number of
passes to cause damage to film, we believe that a five pass limit allows for an appropriate
margin for safety. If lower speed film, ISO 100 through 800, is being carried on
extended trips, and it is necessary to submit the film through security screeners more than
five times, travelers should request hand inspection of their film. I3A further recommends
that all film with an ISO rating greater than 800, black and white films, motion picture
films, and films used for medical imaging ALWAYS be hand inspected. FAA
regulations support the request by passengers for hand inspection of film.
It's all a matter of statistics, and luck. I have had no "functional problems" with slow film (200 and less) but tend not to push my luck beyond 4 to 6 exposures to xray screening... and I always avoid fast film "just because".