Not to mention the recently discovered threat of terrorist implanted exploding boobs:
Exploding Boobs: The Next Terrorist Threat? | Mother Jones
Exploding Boobs: The Next Terrorist Threat?
"Properly inserted the implant would be virtually impossible to detect by the usual airport scanning machines. You would need to subject a suspect to a sophisticated X-ray. Given that the explosive would be inserted in a sealed plastic sachet, and would be a small amount, would make it all the more impossible to spot it with the usual body scanner."