Whole-body scanners or whole-body screening is a new technology that has been developed in order to mitigate additional risks that the walk-through metal detectors we have worldwide do not indicate on passengers. For instance, a knife that is made not from metal but from other ingredients would not be identified by a walk-through metal detector.
I'm a service expert, not a physician, and not a physical expert. But the challenge for the developers of those technologies would be to mitigate the risks of those items that could be concealed in the body and to identify them.
From what I've seen, the technology does go a step further, in my personal, humble, and very subjective opinion, but it's not there yet. On one hand, we have not yet seen 100% waterproof whole-body scanners that would identify without any doubt hidden items that are on this prohibited list. On the other hand, I'm not aware of the official results, but I know that the TSA did some testing--the TSA being the American authority--after the events of December 25, 2009, to try to see whether the whole-body scanner would identify the underwear in which the bomb was concealed. I understood--I don't have the results on hand--that the results weren't so positive.
It is definitely a step in the right direction. From what I have seen personally at exhibitions and in some of the airports in Europe, it is still in the trial process. Some machines have been installed. They still have a problem with the terrible word “throughput”. As you know, one of the things that airports are measuring is how many passengers they can manage to get through a checkpoint in an hour. If a passenger is standing in front of a checkpoint and has to take a lot of items off his body in order to go through a whole-body scanner, that creates a longer process for x-raying those objects. It's a very short process to go through the whole-body scanner, but the whole process becomes longer.
It is a step in the right direction. It is not there yet, but the nice thing about technology, hopefully, is that they will develop a solution that will be satisfactory with regard to this known list of prohibited items in a manner that will not create an additional obstacle for the passengers when they are standing in front of this checkpoint and trying to take off all the shoes, jackets, watches, and pens and whatever.