Review of TSA X-ray backscatter body scanner safety: hide your kids, hide your wife

Last spring, a group of scientists at the University of California at San Francisco (UCSF) including John Sedat Ph.D., David Agard Ph.D., Robert Stroud, Ph.D. and Marc Shuman, M.D. sent a letter of concern to the TSA regarding the implementation of their 'Advanced Imaging Technology', or body scanners as a routine method of security screening in US airports. Of specific concern is the scanner that uses X-ray back-scattering. In the letter they raise some interesting points, which I've quoted below:
  • "Our overriding concern is the extent to which the safety of this scanning device has been adequately demonstrated. This can only be determined by a meeting of an impartial panel of experts that would include medical physicists and radiation biologists at which all of the available relevant data is reviewed."
  • "The X-ray dose from these devices has often been compared in the media to the cosmic ray exposure inherent to airplane travel or that of a chest X-ray. However, this comparison is very misleading: both the air travel cosmic ray exposure and chest X-rays have much higher X-ray energies and the health consequences are appropriately understood in terms of the whole body volume dose. In contrast, these new airport scanners are largely depositing their energy into the skin and immediately adjacent tissue, and since this is such a small fraction of body weight/vol, possibly by one to two orders of magnitude, the real dose to the skin is now high."
  • "In addition, it appears that real independent safety data do not exist."
  • "There is good reason to believe that these scanners will increase the risk of cancer to children and other vulnerable populations. We are unanimous in believing that the potential health consequences need to be rigorously studied before these scanners are adopted."