The US Transportation Security Administration has just published guidelines about what to do with film on an airport. Excerpts:
You should remove all film from your checked baggage and place it in your carry-on baggage. The X-ray machine that screens your carry-on baggage at the passenger security checkpoint will not affect undeveloped film under ASA/ISO 800.
If the same role of film is exposed to X-ray inspections more than 5 times before it is developed, however, damage may occur. Protect your film by requesting a hand-inspection for your film if it has already passed through the carry-on baggage screening equipment (X-ray) more than 5 times. [...]
At the passenger security checkpoint, you should remove the following types of film from your carry-on baggage and ask for a hand inspection:
- Film with an ASA/ISO 800 or higher
- Highly sensitive X-ray or scientific films
- Film of any speed which is subjected to X-ray surveillance more than 5 times (the effect of X-ray screening is cumulative)
- Film that is or will be underexposed
- Film that you intend to "push process"
- Sheet film
- Large format film
- Medical film
- Scientific film
- Motion picture film
- Professional grade film
