Before this thread goes too far with some of the inaccuracies, TSA is held to the same standards as any other federal agency in terms of HAZMAT disposal, health guidelines, etc. X-ray machines are examined once a year, per federal guidelines, for compliance with all safety regulations. Screeners don't wear dosimeters because it was determined that the total exposure is minimal. A doctor explained to me that you get exposed to more radiation walking across a parking lot on a sunny day than you do if you stick your head inside an airport x-ray machine (although he said this doesn't mean he advocates sticking your head inside of x-ray machines!).
Every night, we have a couple TSOs who are specifically trained in HAZMAT who collect all the HAZMAT at screening checkpoints and checked baggage screening locations. They make sure that these items are properly disposed in appropriate containers that are marked in accordance with federal standards (the various classes of HAZMAT) and are stored in an area that has already been inspected and approved as appropriate for temporary storage of HAZMAT. Then every so often (I don't know the exact frequency since I am not HAZMAT-certified), this HAZMAT is transported off of airport property to a designated location for the permanent disposal of HAZMAT.
As for the Privacy Act, TSA is obligated to abide by that as well. I will admit, however, that this is one area where TSA is sloppy not by design but by poor leadership or a poor understanding of how the Privacy Act works. I'm afraid what happens here is a checklist mentality: TSA can show that all of its employees were trained on the Privacy Act but I don't think there's much in the way of following up on the actual compliance. I think some airports are probably pretty good at it and others are not. This is an area where TSA has to follow-through to ensure compliance, but it is not, as suggested, a conspiracy to circumvent the Privacy Act.