A few weeks ago, scientific researchers from top universities released a report confirming my 2012 demonstration that anything can be easily smuggled through the TSA’s nude body scanners. While this (again) made headlines all over the world, the media seemed to have missed one detail that the scientists noted at the end of their study as an addendum: they measured the radiation dose given by these machines and found it to be way higher than admitted.
People were rightly concerned about being dosed by x-rays as a condition of flying from the moment the TSA suggested using nude body scanners. You may recall that the TSA dismissed these concerns — their official line from the very beginning regarding radiation safety:
Backscatter technology projects an ionizing X-ray beam over the body surface at high speed. The reflection, or “backscatter,” of the beam is detected, digitized and displayed on a monitor. Each full body scan produces less than 10 microrem of emission, the equivalent to the exposure each person receives in about 2 minutes of airplane flight at altitude.
Source: Transportation Security Administration, Official Blog
“One full body scan” means one front and back scan, as the Rapiscan systems in use at the checkpoints did both the front and back of your body simultaneously, and the TSA assures us that “1 scan” will dose us with no more than 10 microrem of radiation.
Yet when these independent scientists from University of California at San Diego, the University of Michigan, and Johns Hopkins, who were not commissioned or endorsed by the government, ran the same tests, here’s what they found:
The average DDE per scan for all the dosimeters was calculated to be 73.8 nSv. The average SDE per scan was 70.6 nSv, and the average eye-lens dose per scan was 77.9 nSv.
Source: August 2014 Study, p. 16
Units are tricky with radiation because they are really small and change between “rem” and “sievert” (1 rem = 0.01 sievert), but the scientists are saying that 1 scan = 73.8 nanosievert = 0.0738 microsievert = 7.38 microrem. The TSA promised less than 10 microrem, so it sounds like the TSA was right… right?
Of course not. The scientists, unlike the TSA, did not measure front and back at the same time:
To irradiate them sufficiently, we performed 4033 consecutive single scans in the machine’s normal operating mode. (Each screening consists of at least two such scans: one front and one rear.)
Source: August 2014 Study, p. 16
This means that in order to get front and back, just like in a real TSA screening, we need to approximately double that number and get 14.76 microrem per screening, or about 50% more radiation than the TSA admitted to back in 2010 (or has admitted to ever). While these scientists still conclude that this is a low dose of radiation, it shows that, if correct, we were lied to, again, and anyone who walked through those scanners was given nearly 50% more radiation than they signed up for.
I asked the scientists from the study for comment before publication, and I received a reply from Keaton Mowery at University of California, San Diego, that noted that these kind of measurements have a large margin of error. Well, since these backscatter x-rays are decommissioned and sitting in a warehouse, perhaps it’s time that the government open them up to full scientific study so that we can all know what we were dosed with as a result of the government’s rush to deploy horrendously expensive security theatre that, as study has shown, actually make it easier to sneak weapons through than with an old-fashioned metal detector.
TSO’s will be the first to suffer . . .
then are the tsa workers getting cancer if it is so low??
Very well could be. Just like you wouldn’t see any cancer after a few years of smoking, you may still have increased your risk. In 10-20 years, we may very well find cancer clusters among TSA screeners who were next to these devices for thousands of scans.
Unfortunately, how do we know that this wasn’t just their machine being miscalibrated?
I think when she testified a few years ago in D.C. Wendy Thomson referred to a NIST report that identified leakage in the scanners, which I took to mean the old (backscatter) scanners. Of course government and the medical industry have a history of assuring us something is harmless, then eventually we go on to find it is not.
Oh no! The TSA Nazis are going to get cancer????? Too bad.
Gee, I would not wish cancer on anybody, no matter how much of a scumbag I think (s)he is.
@Loren I’m pretty sure the TSA doesn’t run daily tests of their machines like any medical practice’s would for a machine emitting radiation.
Even if the researcher’s machine was misconfigured, chances are slim that theirs would be misconfirgured *worse* than a machine seeing heavy daily use without a regular checkup.
The other thing that no-one wants to talk about is that the “One-eightieth of a medical X-Ray” you get from these machines isn’t a whole-body dose: it’s all dumped into your skin.
That’s not like a medical X-Ray at all.
Okay, that’s not as bad as focusing the entire dose into your thyroid, but it’s not good. Your skin is has a layer of actively-dividing cells and it’s the site of some of the most dangerous cancers we know.
“The other thing that no-one wants to talk about is that the “One-eightieth of a medical X-Ray” you get from these machines isn’t a whole-body dose: it’s all dumped into your skin.”
It’s not “all dumped into your skin”. That’s just not correct:
X-rays from the scanner penetrate the body and internal organs to various degrees, and materials with a low Z value such as skin reflect X-rays back into the sensor. That’s how the device differentiates between various materials.
If all the radiation was absorbed by your skin, the sensor wouldn’t detect anything since there would be no reflection.
That’s why the quoted UCSD study talks about DDE and SDE as opposed to just SDE.
Are these the old backscatter machines? I think I recall Wendy in her testimony in D.C. citing a NIST report that stated there was leakage (maybe “throwover” was the actual word used – I don’t remember).
Oops sorry! Forgot I mentioned the NIST report in an earlier comment.
Check out this EPA annual dose calculator:
According to your post, each scan exposes the scanned person to 14.76 microRem of radiation, which is 147.6 nanoSieverts. According to the EPA, a typical 1,000 mile flight on a jet aircraft exposes a passenger to 1 extra millirem (10,000 nanosieverts). That’s almost 68 backscatter scans for a typical ~2 hour flight.
I’m no fan of the TSA or these backscatter scanners, but it’s helpful to keep these doses in perspective.