Letter About The TSA Scanners We're Told Are Safe
Contributed by Michael Grabell of Propublica; written by John Sedat, PhD, Professor of Biochemistry & Biophysics, UCSF. An excerpt:
One of the most important issues is that a "Worst Case Failure" mode has not been evaluated. Because these machines are scanning mechanical/software integrated devices, with very intense pencil-like beams of X-rays, if they were to stop in the middle of a scan, there is the significant probability of a radiation burn. What are the consequences, if there were a software glitch or power, even momentary, problems? This important issue, on a machine working 24 hours a day, year in and year out, has not been studied independently and merits major efforts and extensive analysis, not just tested for failure once or twice, given the extreme consequences of a failure.The casual nature for maintenance of these devices is alarming to us. These machines are built with components from clinical X-ray machines and are capable of delivering large X-ray doses. The actual doses are undefined by any objective tests disclosed to us or to the public. Large doses also pertain if there are errors or maintenance problems. Hospitals usually check for problems on X-ray machines daily, but we understand that TSA will only check once a year, at best, in spite of the fact that these machines are being used 24 hours a day, 7 days a week.
The manufacturers are required to notify the FDA immediately upon discovery of an accidental radiation exposure. What is the trigger for discovery? What actions will the TSA personnel operating the system take in the event of a suspected malfunction? Will they notify the individual of exposure to a radiation level of 0.25 mSv, or a level considerably higher if the fail-safe mechanisms also malfunctioned? Who will be directly responsible for the medical care of passengers who are overexposed? How probable are these events? Have exhaustive tests of mean time between failures for these systems been done in realistic operational settings? How often will the machines be calibrated? The damage from an accidental overdose may not be quantifiable for many years after the exposure. It will be difficult to determine delayed medical consequences of overexposure.
In Summary, A Change is Needed
To summarize, the above points strongly indicate that independent test(s) have not been adequately performed for X-ray scanners leaving us in a situation where a major untested technology is being used on a large segment of our population, and where any damage may not be apparent immediately, or recognized to be caused by the extra radiation exposure - an unprecedented state of affairs.We urge that independent testing and analysis of the entire technology be initiated immediately. Until then, given the potential health complications and the fact that a large segment of our population is being subjected to these machines as a primary screen, we strongly suggest that there be a moratorium on their primary use.
I find this sort of thing occurs among professional engineers all the time: they extend their "expertise" beyond their sphere of experience.
How so?
"The actual doses are undefined by any objective tests disclosed to us or to the public."
False.
Except, of course, that the tests I have already linked to were done by an agency not required to report to anyone at their whim.
This person and his parent organization can do the legwork themselves - sometimes, merely asking for a blueprint, because the technology isn't patented generally and non-disclosure can be effected for those areas which are - or they can complain publicly. Hmm. Which to choose?
On this issue, like so many others, people know money is to be made in confusion. If they can cause it, so much the better.
The "Z Portal" has been installed and in use at seaports for years. It's so noce to know that such a vigilant public watchdog is on the job!
Radwaste at January 17, 2012 2:57 AM
All I can say is, I'm still not impressed. If those sorts of dose rates worry you, then never get on a plane again. Especially not intercontinental. Don't live anywhere with significant granite deposits either. (I'm a professional engineer Rad, and it's not my field - I'm smart enough to listen to people who do know what they're talking about though).
There is one famous case I know of where accidental, and serious, radiation damage was caused by malfunctioning/badly operated machines. I'm sure Rad is familiar with it.
http://en.wikipedia.org/wiki/Therac-25
But note that the problem here was kicking the electron beam into high power *without* the target required to generate X-rays in place. The X-ray output by itself would never have been enough to cause serious problems. For machines that aren't dual purpose like that, I'm not seeing a problem health wise. Whether it's worth doing is another story.
Ltw at January 17, 2012 3:44 AM
I find this sort of thing occurs among professional engineers all the time: they extend their "expertise" beyond their sphere of experience.
On a side note, I've noticed this too. Working in a multidisciplinary field you get a lot of amateur "experts" poking their nose into what you do.
Hell, it's good oversight I suppose, and having to justify yourself to them helps ensure you're on the right track. On the other hand, that's what my chief engineer is for, not some MBA who thinks he can break the laws of physics.
I've done it too of course. On a tunnel project I was the liaison for my group (control systems and control room design, electrical distribution) to the working party settling the head office building design. Which included my control and equipment room. Which was all I cared about, although everyone else had their own agenda. For a while - months - all of us were bringing in cut and pasted (literally - with scissors, glue, and red pen) versions of the floor plan drawings to the meetings. The look on the architects' faces was sad to see. "No, you can't put a wall there. No, that contravenes building regulations. No, that door just won't open."
Ltw at January 17, 2012 4:16 AM
I hear Radwaste's complaint frequently on the net, in all sorts of topics. Not just engineers.
It's a nice appeal to authority, which sometimes is valid, and sometimes not.
But often, a person can very reasonable extend their expertise beyond their experience. Why? Because by definition of the fundamental nature of the logic of mathematics and the natural laws that govern chemistry, physics & biology.
Example of a physicist sticking his nose beyond his expertise:
http://www.awesomestories.com/assets/dr-richard-feynman-discovers-the-oring-problem
jerry at January 17, 2012 6:43 AM
For the Challenger explosion, the engineers involved were well aware of the O-ring issue in low temps jerry. They were overridden by management and they didn't really need a physicist to tell them. It's one of the case studies of that particular phenomenon.
I'm not appealing to authority here (if you ask me, John Sedat, with his Professor of Biochemistry and Bullshit etc is the one doing that). Radwaste is providing some evidence based science, which in my opinion - reviewed with my fairly worthless undergraduate physics degree - looks much more plausible. Yes, people can reasonably evaluate stuff outside their field - but it's a good idea to listen to people who know the details first.
Amy, I'll support you on this issue on 4th Amendment grounds, but not on cancer risk. It's crap, plain and simple.
Ltw at January 17, 2012 7:01 AM
"For the Challenger explosion, the engineers involved were well aware of the O-ring issue in low temps jerry. They were overridden by management and they didn't really need a physicist to tell them. It's one of the case studies of that particular phenomenon."
A) You need to relook at the record. The engineers were aware of a problem, but were badly analyzing it with respect to the statistics they applied. They knew they had a problem on many flights, but they never actually performed Feynman's simple test and simple conclusion. Instead they tried to apply statistics to it to come up with probability of failure given a temperature, and even then they applied their stats to the wrong data set.
B) You're also missing the point entirely.
It's totally appropriate for laymen to speak up, they often have a lot of value to add, and it's mainly just whining by the so-called, self-claimed experts to demand they be suppressed.
jerry at January 17, 2012 7:35 AM
The first few comments are interesting, considering that DHS has been forced to admit that it is monitoring social media for stories that portray it unfavorably (http://news.slashdot.org/story/12/01/14/233203/dhs-monitors-social-media-for-political-dissent). Perhaps they're posting too. Who do you work for, Radwaste? Ltw?
Be that as it may, Dr. Sedat's credentials appear to be appropriate for the subject in question. Biophysics is one of the disciplines most directly relevant to this discussion.
Paul F at January 17, 2012 7:37 AM
Who do you work for, Radwaste? Ltw?
Oh please. My checks come from the Rand Corporation, of course. But my super secret cover story is
http://ugllimited.com/
I pretend to work on road, rail, and tunnel projects - in Australia - while secretly monitoring your inane twitterings. Sshhh! Don't tell anyone.
Ltw at January 17, 2012 2:06 PM
Paul F.: I work for a division of URS, at Savannah River Remediation, where I process nuclear waste generated in the production of atomic weapons (mostly) and assorted other isotopes at Savannah River Site. I'm assigned now to a job determining what the process and procedure impact is when design engineers make changes, chiefly due to obsolescence. Our junk is up to 58 years old.
(In my spare time, I try to explain this to Crid, who worships me, but is ashamed of it to the point that he becomes incoherent.)
Credentials aren't the point. The foundation of the fallacy, "appeal to authority" is the mistaken idea that credentials = correct. In fact, credentials mean that the person should have the resources to understand and argue the issue at hand. It remains that such a person must demonstrate the support for any idea he or she espouses, and most of the time, other than in popular media, where material is routinely edited to appeal to the public, this happens.
Not this time. Thus, the "false".
Radwaste at January 17, 2012 3:55 PM
That must be a fascinating job Radwaste! Feel free to get my email from our hostess and include me on your discussions with Crid. In return I have a few war stories about some of the insane things people do on roads, and some terrifying engineering fuck ups. Including a bloke getting a 6 axle semi to push his Lexus out of a flooded freeway ramp (it was floating), but to avoid damaging his paintwork he sat on the rear bumper and put his feet up on the truck. The human shock absorber...he was a big, strong guy and actually managed to do it, two ton of car and he held the truck off while it pushed him up the hill. With his feet. I saw the video and my legs ached just watching it.
Ltw at January 17, 2012 9:33 PM
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