|UCSF Scientists Question Safety of TSA Body Scanners
Content | November 19, 2010
Medical concerns over the use of full body scanners by TSA agents at airports has hit critical mass finally. While many have been concerned about privacy issues and others have been happy to joke about the "nude scanning devices", there are legitimate medical concerns being raised by the use of the X-ray technology employed in full body scanners. The people raising the concern are hardly sensationalists or crackpots, it is a consortium of specialists in the field who are NAS members in good standing.
The X-rays used in the current full body scanners at airports have been cited by this group as "Compton-scattering off outer molecule bonding electrons" which means that the X-rays are likely to some degree breaking bonds. Although the beam used is 28keV which is low beam energy, that energy is cited as safe when distributed throughout the entire body, not focused on the skin and underlying tissue as is the case with the airport scanners. Because of that, the risk of damage to the skin and underlying tissue is cited as potentially being dangerously high.
There second big concern is that they feel independent data does not exist which sufficiently demonstrates the safety of the scanners. Without pointing fingers too harshly in a letter addressed to Dr. John P. Holden, Assistant to the President for Science and Technology, there is an underlying tone which suggests that the researchers that cleared the scanners for use where perhaps not sufficiently qualified to do so or possibly misrepresented or shielded their data.
As John Sedat. PhD., professor Emeritus of Biochemistry and Biophysics UCSF, David Agrad, Ph.D, Robert Stroud PhD., and Marc Shuman, M.D., all point out in said letter, the data does not foot and needs re-evaluation. In said letter they state:
"In addition, it appears that real independent safety data do not exist.
A search, ultimately finding top FDA radiation physics staff, suggests
that the relevant radiation quantity, the Flux [photons per unit area
and time (because this is a scanning device)] has not been characterized.
Instead an indirect test (Air Kerma) was made that emphasized the whole
body exposure value, and thus it appears that the danger is low when compared
to cosmic rays during airplane travel and a chest X-ray dose. In summary,
if the key data (flux-integrated photons per unit values) were available,
it would be straightforward to accurately model the dose being deposited
in the skin and adjacent tissues using available computer codes, which
would resolve the potential
They then went on to detail eight specific health concerns that are known to exist from X-rays that they feel are elevated due to the use of these body scanners which include:
1. Possible damage to the cornea and thymus
7. The mutagenic effects of X-rays in patients over 65 in regards to
Concerns over the hardware and software in the full body scanners have also been raised. It is cited that any error to either can cause an intense focused dose of radiation which is an obvious problem, particularly if that dose were delivered to the groin area. IT is further pointed out that so far there is little if any known regulation regarding tweaking the technology to provide a better signal-to noise ratio to improve the resolution of scans which could increase the total dose of radiation people receive.
What can be taken from this is that it is evident full body scanners used at airports may have been rushed out a little bit. It is vexing that not all of the supposed study data regarding the scanners has been released. It is further problematic that no one can seem to find any regulations that stop manufacturers of the scanners or the local operators of said scanners from tweaking the manner they operate which could cause an increased health risk.
The gentleman behind this push are not saying that scanning is unnecessary, but what they are saying is that independent research or verification of all existing research related to full body scanners is needed. They are not saying that everyone that goes through a scanner will face grave health issues, but that there are concerns regarding a significant enough portion of people that will go through security scanners that is insufficiently addressed. For what it is worth, no public reply to these concerns in full has been made to this point, although there have been promises of further investigation at some point.