I've been throwing all my film through airport scanners and haven't had any noticeable problems, even with 400 film. HOWEVER, at Rome Flumi[...] their scanners are not safe for film, and they have signs that say so (in English). There I requested a hand scan (I had 35mm film and one 35mm camera), and they didn't really do much, just looked at the film and the camera and did a swipe test. Hopefully they'll do the same with 5x4.