
TSA compton backscattering exposes body to non-negligible radiation (2010) - hovden
http://www.public.asu.edu/~atppr/bodyscan.html
======
bonzini
This article is from 2010. These days the TSA is using millimeter wave
scanners (with frequencies around 30 GHz).

~~~
djsumdog
Yea I was thinking that. The back-scatter xrays are all gone, but they were
not as safe as this article is trying to make. There were a lot of
radiologists who were concerned.

The millimeter wave machines are less dangerous, but they also don't really
work well at all and have a high false positive rate. They're pretty much
security theater, which we're seeing a lot of again now.

~~~
m0zg
> There were a lot of radiologists who were concerned.

Would those be the same group of people who are "concerned" about 5G towers
today? You can always find a small group of people who are "concerned" about
anything you like. The press uses this for nearly every such story they
publish. Without statistics quantifying that "a lot" the statement is
meaningless. And even if you have the statistics, there being "a lot" of them
is not a guarantee that they were right. One would need to present evidence
for their concern as well to be treated seriously. Such evidence does not
exist, since airplane flights themselves are a source of radiation exposure.

[https://cdn.vox-
cdn.com/thumbor/DZqWhneDEMxElDzz7ZiUk0Jv93w=...](https://cdn.vox-
cdn.com/thumbor/DZqWhneDEMxElDzz7ZiUk0Jv93w=/0x0:1599x7185/1520x0/filters:focal\(0x0:1599x7185\):format\(webp\):no_upscale\(\)/cdn.vox-
cdn.com/uploads/chorus_asset/file/4030924/RADIATION-FLIGHT-DOSES.jpg)

~~~
TeMPOraL
A very reasonable heuristic for life is: you should not be concerned about
non-ionizing radiation (like 5G), unless in doses that could burn your face
off. You should, by default, be concerned about ionizing radiation (like
x-rays) in any dose above the natural background.

~~~
acidburnNSA
That's been the heuristic since the 1950s. Now we have much more data on low-
dose ionizing radiation. Regulations still assume linear no-threshold, yet no
one has definitively shown that anything below 100 mSv causes harm or good
using vast amounts of data (c.f. US natural background of 3 mSv/yr). Thus, my
rule of thumb is to start worrying only if I get more than 100 mSv either
acutely or integrated over a year.

I worry a lot more about eating hamburgers than anything less than 100 mSv.

~~~
TeMPOraL
I agree, and didn't mean to imply otherwise. I was focusing more on the point
about ionizing vs. non-ionizing radiation, which I swear to god had to drill
into random people's heads in every imaginable way and combination.

I assume this chart is still good to show to people:
[https://xkcd.com/radiation/](https://xkcd.com/radiation/)?

~~~
acidburnNSA
Gotcha. Yeah lots of people don't get that.

Yeah I still love this chart!

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acidburnNSA
With radiation, I always recommend people study page 6 of this DOE radiation
dose range pdf [1] to put dose rates in context. The spectrum of radiation
doses spans many orders of magnitude and a single atom decaying is readily
detectable.

Note in particular that there are places on Earth like Ramsar, Iran that have
natural background dose rates above 50 mSv/year and no one has been able to
show definitively that dose rates at or below that level do or do not cause
harm (or benefit!).

[1] [https://www.energy.gov/sites/prod/files/2018/01/f46/doe-
ioni...](https://www.energy.gov/sites/prod/files/2018/01/f46/doe-ionizing-
radiation-dose-ranges-jan-2018.pdf)

Another fun data point is the longitudinal studies of flight crew who spend a
good part of their career exposed to higher-than-normal natural cosmic
radiation (while flying they are above much of the Earth's protective
atmosphere) [2]. We should compare how much dose we get from the scanners at
airports to how much we get from intergalactic protons raining down from the
cosmos while we're up in the air.

[2]
[https://www.bmj.com/content/325/7364/567](https://www.bmj.com/content/325/7364/567)

One time I took a geiger counter on a flight just for fun [3]. It really was
clickin'!

[3] [https://whatisnuclear.com/blog/2014-05-17-radiation-on-
fligh...](https://whatisnuclear.com/blog/2014-05-17-radiation-on-flights.html)

~~~
hammock
I don't get why a full year's worth of background radiation is always compared
to an acute 5-sec (or less) exposure from an x-ray machine.

If the background rate is 50msv/year, and a machine doses that much (50msv) in
5 seconds, that's 6.3 MILLION TIMES greater than the background dose.

~~~
sizzle
This is an excellent point, does an acute dose of radiation in a short
timespan cause more cellular damage than long-term exposure?

~~~
acidburnNSA
Absolutely yes. But acute low-dose below 100,000 μSv has never been shown to
cause or not cause harm.

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toufka
The open letter from biophysicists at UCSF _at the time_ outlined many of
these concerns [1]. It was clear that the way these machines were being
assessed was not scientifically rigorous, and were likely dangerous. The DHS
Secretary Michael Chertoff had an interest in the company selling the scanners
[2]. The damage done to the public’s trust and the public’s DNA by forcing
these machines on people was awful.

[1]
[https://www.thestranger.com/images/blogimages/2010/11/17/129...](https://www.thestranger.com/images/blogimages/2010/11/17/1290049297-ucsf-
jph-letter.pdf)

[2]
[https://en.m.wikipedia.org/wiki/Michael_Chertoff](https://en.m.wikipedia.org/wiki/Michael_Chertoff)

~~~
javert
DHS is a far bigger threat to our freedom than terrorism.

In "policing" work, there is a line where you become a bigger threat than the
bad guys, and you become the bad guys.

Many DHS agencies don't care. They are self-perpetuating institutions that act
in their own "institutional" interest.

Note to DHS language parser: this comment should be classified into your "big"
database ("normal patriotic American complaining about gub'ment"), not your
"small" one ("actual threats").

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georgeburdell
Has anyone seen these recently? I saw one in Boston many years ago, but every
airport I've been through since uses the mm-wave ones, distinguishable by
their rotating action

~~~
armitron
It boggles my mind that people accept to be treated as lab rats with unknown
consequences to their health decades down the line, just so an utterly useless
bureaucracy can justify its existence and certain political goals can be met.

Of course the TSA is just the tip of the spear. As James Duane so powerfully
demonstrates in his talk and book [1], the number of gun&badge toting Federal
agencies with the power to ruin one's life, sometimes even making up crimes to
do so, has been steadily increasing. As has the number of nonsensical criminal
statutes and regulations in the books.

[1] [https://www.cato.org/events/you-have-right-remain-
innocent](https://www.cato.org/events/you-have-right-remain-innocent)

~~~
minaguib
Since their introduction, I've had no issues telling the agent "I'd like to
opt out of the scanner". This adds ~10 minutes as I have to wait and perform a
manual pat-down, but personally that's not something I mind. Others obviously
may feel otherwise for varying reasons.

I've found this article (10 years old now, :
[https://www.health.harvard.edu/diseases-and-
conditions/are-f...](https://www.health.harvard.edu/diseases-and-
conditions/are-full-body-airport-scanners-safe) ) to be fairly well-rounded. I
wonder if, since then, there has been a better analysis of actual/measured
results of these technologies.

~~~
cgearhart
I have always opted out of these scanners as a matter of principle. (To wit, I
think it’s an erosion of privacy.) But you should know that the TSA changed
their guidelines such that granting a request to opt out is effectively up to
the discretion of the TSA agent at security. Their new guidance says:

>While passengers may generally decline AIT screening in favor of physical
screening, TSA may direct mandatory AIT screening for some passengers.

I found out about the change as I was going through security and opted out.
The folks in line behind me said “I didn’t know you could do that” and a queue
formed of folks opting out. They made everyone else behind me go through the
scanner, saying that it was a security risk to have folks queueing to opt out.
(It’s a security risk to form a queue inside a long security screening queue?)
The reality is that this rule change was needed so that they could avoid the
screening process grinding to a halt if everyone requests a manual screening.

[https://onemileatatime.com/tsa-scanner-opt-
out/](https://onemileatatime.com/tsa-scanner-opt-out/)

~~~
kilo_bravo_3
The nudie-scanners have been gone for over six years and the current scanners
are nothing more than (at a high level) low-resolution "difference" detectors.

The only way they'll invade your privacy is if your genitals are made out of
metal. And no, genital piercings don't trigger them.

With ATR (automated target recognition) scanners it is literally, definitely,
assuredly, irrefutably impossible to reconstruct any image or representation
of the human body in any capacity approaching useful or attributable using
2020 scanners.

What are the privacy ramifications of 2020 airport scanners?

Not 2014 scanners. I do not care about something that does not used anymore.

I would assert that a patdown is an infinitely greater "erosion" of privacy
than the post-feature and contour extraction comparison of phase history data
to a generalized model of the human form.

~~~
catalogia
Who cares if there aren't privacy implications? It's still security theater
and should be opposed on principle. Anything beyond metal detectors is
pointless. You can't hijack airplanes anymore because the other passengers
won't comply with hijackers anymore; that was proven on 9/11, long before any
fearmongering bureaucrats imposed any of their corrupt theatrical horseshit.

~~~
kilo_bravo_3
In what way is it security theater?

It’s real and it works better than the technology it replaced.

~~~
catalogia
Would you be interested in purchasing a tiger-repellent rock from me? I can
guarantee that if you purchase one of my rocks, no tigers will eat you.
They're real rocks, I assure you.

------
appleflaxen
If everyone opted out of the scanners, they would quickly disappear.

~~~
Someone1234
I opted out of backscatter back in the day (and looking at the facts
retrospectively I feel validated in doing so, for example the miscalibrated
units found to be spitting out 20x more radiation than designed).

I don't opt out of Millimeter Wave today, as I'm yet to see convincing
scientific arguments or evidence that they're unsafe, or what the mechanism
would be outside of mild tissue heating. I do choose to close my eyes when
scanned though, take that as you will.

~~~
cosmotic
Have you seen any convincing scientific evidence that they are effective? I
mean... Do they stop terrorism? They may not give you cancer but those
machines aren't free.

~~~
Someone1234
Beyond the scope of opt-outs. This is more a political question masquerading
as a scientific inquiry.

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latchkey
I really don't worry about the low levels of radiation or not.

What I worry about is trusting the TSA to keep these machines operating
correctly and within spec. The care they give the machines cannot be greater
than the care they give to the employees, and we know how well they treat
employees.

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godelski
This article is a little absurd. They are talking about uSv (10^-6) than give
the big warning

> Scary thing, what happens if scan jams and fail-safe mechanism fails --
> local dose very high of order a few Sv

We can do this with anything. I'm not so concerned about these machines
failing in a region that typically has radiation monitors. Sure, we should be
concerned with machinery failing, but the amount one should worry isn't
proportional.

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settsu
It’d be fascinating to know how many products, or entire businesses, are able
to exist or even thrive through broad ignorance (whether willful or naïve) of
their true nature.

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johnklos
.emf files on a web site?

There's a reason that the scanner manufacturers got exemptions so they
wouldn't have to report measured radiation.

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javert
Needs to be retitled (2010)

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ryanmarsh
Looking forward to the epistemological study in my 70’s after I’ve had my
prostate ripped out, wherein we find men who traveled frequently post 9/11
were at increased prostate cancer risk from millimeter wave tech.

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madengr
I can’t recall the name of the principle, or the exact dose, but isn’t 1 Sv
enough to cause a 50% death probability from radiation sickness, and 3 Sv
enough to cause a cancer? There is a good youtube series (IIRC nuclear policy
course at MIT) I was watching when the Chernobyl show was on last year.

So 0.25 mSv is enough to cause a cancer for every 12,000 people they scan.
That’s a lot of people considering the throughput of airports. Lovely. I’m
glad this was shit-canned.

~~~
vkou
You have 4 litres of blood in your body.

You will die if you lose 2 of them.

A typical lab blood draw is ~10 ml.

Does this mean that for every two hundred people who get their blood drawn,
one is killed?

~~~
madengr
Of course not, but if I inject you with 2 L of peanut oil, it will kill you.
If I do the same at 1 ml to 2000 people, maybe the statistics work out so a
single, hyper-allergic person is dead. That’s all the linear approximation is
saying, and that lecture series says it has held true. The interesting thing
about it, is the dose for a single cancer is above the lethal dosage.

