Here's a link to a study NIOSH did. The results are pretty much what's been stated. The machines are poorly maintained and some release more radiation than they should have. Poor work practices were noted such as reaching into the machine too far. They also put dosimeters on employees at six airports which did show radiation exposure, in a couple instance exceeding the public limit.
Sounds like TSA has pretty clearly violated labor laws if they had no rad-control program at all, when clearly there is potential (it's also one of the things cited in the NIOSH report).
Gonna see what OSHA has to say....
Edit - just a note. the NIOSH study was done in 2008, prior to the full-body scanners being in the airports in force.
Edited, Jul 1st 2011 2:04am by Elinda