So apparently the TSA says: "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."
And the author says the dose is really 14.76 microrem, but doesn't dispute the equivalence to flight time. So really it's equivalent to 3 minutes of flight, not just 2.
50% of trivial is still trivial.
Oh, and the author says that the margin of error on these measurements is large. So perhaps the TSA didn't lie at all, they just measured 10 microrem. Even if the margin of error is 1000% the result is still trivial.
So... basically this is non-news about a technology which isn't even in use anymore. The TSA now uses millimeter wave technology as the author is aware ("these backscatter x-rays are decommissioned and sitting in a warehouse").
There are a lot of good reasons to be concerned about the TSA's use of imaging technology. This is not one of them.
"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."
The point is not that 14µrem is dangerous to an individual on occasion, it's that the government irradiated us at a rate different than what they promised.
It will also have societal effects. I've seen calculations that estimate that something like 6 people will die from cancer as a result of the radiation from 700M TSA screenings given per year. That estimate should now be adjusted, and we should again say, "How many lives does the TSA save that justifies this?"
I haven't seen the particular estimate but it's very difficult to extrapolate repeated low doses into a high dose.
Lets take the case of water toxicity, if you're a little dehydrated and you drink 5 litres of water in one sitting you'll die. However, if you drink a few litres of water everyday over the entire day you'll have no issue.
He answered your point in his comment. The TSA said these measurements had a fair amount of error associated with them, and since their still trivial amounts it's unfair to say the TSA lied when the number is within what they said it would be.
You're getting upset over nothing. Really, you are. There is a LOT to get upset at TSA et al. over, but all this hurt the anti-TSA case.
It's 10 vs 14. Neither is significant, neither matters. All measurements have errors, if a source is claiming otherwise you best assume they are not educated very well on science - and have not done a good job communicating with the scientists making the measurements. So as far as anybody is concerned, the difference between 10 and 14 is so insignificant it may as well be less than 10.
I don't know about the people you're responding too, but for me it's less about broken promises and more about incompetency. I would be almost as angry if the number were 6, when they promised that they had done proper testing of the equipment.
That was my mistake. The author of the piece said that the scientists responded saying their measurements have a large margin of error (Unfortunately, he doesn't tell us exactly what they said).
These machines give you a dose of $\mu + \epsilon$ rems, where $\epsilon$ is random with zero mean. TSA's claim amounts to $\mu = 10$ and (presumably) $\epsilon$ normally distributed with $\sigma$ small. Now it turns out that $\mu = 14$. I agree with you that, in isolation, this is inconsequential. Taking a step back though, you have to wonder: if they are incapable of measuring $\mu$ accurately what else have they gotten wrong? In particular, suppose that one time in a million scans this machines messes up and administers a dose of $10000\mu$ (about 1mSv). A few unlucky people a year would be on the receiving end of that -- would you like to be one? This may seem like tinfoil-hat nonsense to you but if you read about the shady way these machines were sold to the government and the farcical "testing" that went on before they were deployed it doesn't seem completely implausible. At least, I'd like to see a lot more openness about how these things work, plus more third-party verification, before really trusting anything coming from the TSA.
But nobody was saying they're wrong except for this author. I question why you're so quick to trust this random author. The author himself explicitly states he emailed the scientists who did this study, and all he says about it is a quick note at the end of this article where they said the amount of error in their results means the TSA could still be telling the truth. IE. The scientists who did this study are saying that their findings aren't enough to prove anything about the TSA, but the author is saying they are. The author also didn't reproduce anything of what the scientists actually said to him. IMO, I don't blame you for not trusting the TSA, but there's nothing about this article that makes it particularly trustworthy either.
See this letter by UCSF biophysicists & oncologists written to the Whitehouse with concern for these scanners.[1]
Their point is that the 'overall' dose is, not only unknown, but measured in a non-meaningful way. "Garbage-in, Garbage out." A full body scan produces 10 microrem of emission, concentrated to the first few microns of skin - (which happen to be where gonads, breast tissue, skin & eyes are...). This is very much unlike riding in an airplane where the exposure is truly whole-body. The "expose per cell" in these two cases is wildly different.
Does this actually matter? If each cell has x% probability of becoming cancerous when hit with a single ray of radiation, then shouldn't the probability of getting cancer is the same either way?
The answer is mostly, we don't know. However, we do know that most of your cells in your body are not really capable of becoming cancerous. In general (again, generalities here - we don't have enough data), only dividing tissue is really capable of becoming cancerous. But most of these dividing tissues are those mentioned above and likely to be some of the cells exposed to such a machine (immune system (not near the surface), skin, testes, breast tissue, digestive system). The tissues at the surface of your body are disproportionately susceptible to cancer.
Cancer very much is a stochastic event, and so probabilities are all we can talk about. But reducing the number of encountered objects by billions-fold while keeping the rate of exposure the same can wildly skew data that you had relied upon to determine a 'safe' dose.
There's still a difference between the kind of radiation exposure that occurs during a flight compared to during a screening. My understanding is that radiation exposure during a flight is due to cosmic rays which are equally likely to cause damage throughout the body. The X-rays used by the TSA are at lower energy and are deposited almost exclusively in the skin. Since the volume of skin is much less than the total volume of your body, the radiation dose that your skin is receiving from the TSA is much larger than the dose during a flight.
While I'm very glad they're no longer in use in airports, I never saw a satisfactory answer to this. Perhaps I misunderstand the physics here, but wouldn't 10µrem across 100% of tissue be equivalent to, for instance, 1,000µrem across 1% of tissue?
Yes, that's correct. However, the difference in damage that that will do is still not clear. It's possible that skin tissue is more susceptible to damage than other kinds of tissue. (Or perhaps it's less susceptible.) Moreover, low-energy X-rays may do different kinds of damage than relatively high-energy X-rays or cosmic rays. Just looking at rem ignores a lot of variables about the long-term biological effects of the ionizing radiation.
I'm just concerned a wildly mis-calibrated machine might output 10 millirem of radiation and nobody would notice.
Considering how oblivious some companies are to the difference between $0.02 and 0.02 cents, milli and micro might be way beyond the ability of some TSA technicians to understand.
Of course these new machines cannot fail the exact same way as the Therac 25. But could they fail in a new, unpredicted way? I dunno. I am not familiar enough with how the backscatter machines are implemented to be able to predict how they could fail. But I maintain neither are most of the people who defend these machines as safe.
It's very safe to say it's beyond their ability to understand, considering that the TSA operators were never required to take the same health physics courses that literally everyone else whose job involves exposing the public to X-rays must undergo.
Perhaps the reasons given in the article were not compelling on their own, but the author's point was that the TSA overstated their case.
Researchers have pointed out that international pilots and stewardesses may already receive more cosmic radiation than may be safe due to high altitudes and long duration. This is why they're allowed to skip the scan. Why shouldn't frequent international business travelers receive the same treatment?
Also, all machines have a percentage of possibility of breaking down or misbehaving. Do we want to subject someone to the possibility of being irradiated by a damaged scanner when the odds are greater than harm from terrorism?
I don't want to get too down on the TSA corporation since their public facing staff have always been polite and pleasant enough to interact with. I always opt out, so I have to get searched, but they are polite about it.
That said, I don't like it that TSA staff don't wear radiation badges, at least I haven't noticed any. One lady working for TSA, at the backscatter device, was very pregnant and I wondered about the radiation hazard for her, if any.
They get quite defensive when you ask why they don't wear dosimeters. Their immediate answer is that the machines have been proven to be safe. But when you point out that one of the purposes of dosimeters is to measure accidental exposures in otherwise safe environments, then the cognitive dissonance really starts :>
Q: Why aren’t your officers permitted to wear dosimeters?
A: There is a really good reason for this. The emissions from our X-ray technology are well below the requirements that would require their routine usage. To help reassure passengers and employees that the technology is safe, however, health physicists with the U.S. Army have been conducting area dosimeter surveys at multiple airports nationwide.
Sounds like nonsense to me... at the least, I'd like to see the resulting data from those surveys posted online and kept up to date so the public can see it.
This is insultingly nonsensical from the TSA. The reason they list might be a reason not to require dosimeters, but it's certainly not a good reson to prohibit it. And it's not a good reason not to require it, either, since the purpose of dosimeters is not just to measure radiation accumulated by an operator, but as part of the alert system for a malfunctioning device.
The entire thing is theatre so why wouldn't they keep up the theatre.
The funny thing is most of the fear stems from TSA style non-sense that has people freaked out about radiation. Everyone worries about dirty bombs, and TSA x-rays, fukushima, no one about the thorium / uranium released from burning coal.
I've always opted out, but they (on purpose?) make you wait and get nervous about your belongings. Sometimes I've waited 15 minutes for the pad down guy to show up and my stuff was unattended all this time.
I always hold my stuff up before it enters the scanner; this serves the dual purpose of making it harder to ignore my request and keeping my bags safer. Usually they'll then ask you to hold your belongings outside the line or put them on a shelf somewhere in eyesight.
I've never been allowed to. They always make me run them thru the X-Ray and wait in the separate line until the guy shows up... which varied between 5 and 15 minutes. Then the guy usually shows up and starts making faces and keeps reciting the rules. I told him: I'm in a hurry, I agree, I've heard this a million times already, but, no, he needs to repeat the same thing over and over again.
I'd be interested to hear their response if you said "I prefer to keep my belongings with me until I can go through with them."
In fact, on occasion I've had them insist on me keeping my belongings outside the scanner. I wonder if it's a liability for them to have them back there where I can't monitor them. After all, the screenings are always conducted with your luggage in eyesight.
This gets much harder if you have a family and all want to opt out. Of course, a crying or annoyed kid usually provides sufficient motivation to TSA to not keep you waiting as long as you stay courteous (as much as possible given the conditions).
Last time my family and I went back to Europe, at Tom Bradley International Terminal at LAX, our family was directed to a special families-only line, which didn't have full-body scanners at all, and didn't even do pad downs - just went thru the old-fashioned metal detector and X-Ray for the carry-on luggage. We were pleasantly surprised as we were expecting the old nightmare.
Traveling with my kids has been easier (in this regard) because the family line doesn't have the full body scanners at any of the airports I've been through (Atlanta, Chicago, Dallas, Houston, Denver, Seattle ...). Traveling alone I usually have to opt out, though sometimes one can choose a line without a scanner.
Last time I opted out at JFK, the TSA agent I told I wanted to opt-out was like "You want to what?" and stared at me in complete confusion. After I finally made her understand that I didn't want to go through the machine, she was extremely rude. It was very strange.
The bigger problem are the TSA agents operating the scanners. They are constantly getting exposed to these machines during their workshift. I think that's the biggest upcoming "disaster" surrounding these lame ineffective scanners.
The "body scanners" do not use X-rays. They use millimeter waves, which are totally different. Most importantly, millimeter waves are non-ionizing and therefore safe, unlike X-rays.
- Inflammatory headline irrelevant to content ("Nude" Body Scanners)
- 50% more than an insignificant amount of radiation is still insignificant, and likely difficult to measure precisely. The idea that the TSA would "lie" about this is silly.
- I'm not a fan of the TSA, however inflammatory articles are not what I look for on HN.
Opting out is the easiest way to protest these machines. Just tell the person running the machine, "I opt out!" before entering it, and they will pat you down instead of using the scanners. Considering the false-positive rate of the scanners, you may get pat down anyway, so might as well protest and skip the dose.
I've finally given up on opting out, or perhaps I should frame it as finally declaring a partial victory and moving on. I still think the scanners are a huge waste of money and time, but they've gotten better.
The x-ray versions are gone (and with them any small chance of dangerous radiation exposure). And I'm told that they no longer show your naked body to agents, but rather a generic outline that labels potential objects of concern. So the things about them that I've felt had the potential for a direct negative impact on me personally are mostly in the past.
Because of that, the last time I flew, it struck me that opting out was purely a political protest, and that the only effect it was likely to have was to make things flow a little bit less smoothly for all the other poor folks standing in the long line behind me. I just didn't see the payoff anymore. So for the first time, I went through the blasted machine. They did a quick patdown anyway, but I guess that's par for the course.
I wish I knew a way to take an effective stand against this system. But I've ceased to believe that opting out is it.
Actually, the agents don't see anything unless the machine detects a "potential threat item", then they see the generic outline. See: http://www.tsa.gov/ait-how-it-works
One could argue that making things flow a little bit less smoothly is a positive effect in and of itself. If the powers that be see that they're getting no actual security and snarling lines perhaps they'll come to their senses.
> the only effect it was likely to have was to make things flow a little bit less smoothly for all the other poor folks standing in the long line behind me.
Why should it have this effect? When I opt out, they have me stand in a little area off to the side until a scanner is ready for me. I don't hold up the line, and, as far as I know, most people don't even notice that anything is happening (except that some wonder curiously why I am electing to stand around, apparently for recreation, without belt or shoes).
Random? What are you talking about? You've never seen that amazing iPad app that the TSA officers use to tell you which line to get in? You know... the one where they tap on the screen and a large arrow tells them whether to send you to the left or right? And for which they probably paid tens of thousands of dollars (maybe more) to have built? Wish I had gotten that contract! :-p
That just picks whether or not you get PreCheck if you weren't already on the list. It doesn't necessarily determine if you're in a metal detector or MMW line (though PreCheck lines only have metal detectors).
If you're opting out, you're already not blindly following their orders. So why would you stand right next to the machine just because they said so? I make sure to stand a comfortable distance away, and if harassed I tell them that's as close as I'm comfortable with. It also seems to cause a bit of confusion to the lemmings going through the microwave^wmilliwave, who feel bad about cutting in front of me. I also wouldn't be surprised if that turbulence causes the molester to arrive quicker than they would otherwise.
Yep, I have never not waited at least a few minutes for someone to come over and pat me down. Once I waited 10 minutes at SFO, and I had to ask the same TSA agent who was nearby multiple times to get someone. I was in fear the whole time that my laptop, just waiting around on the other side of the conveyor belt, might disappear.
yay for opting out! wish everyone would opt out... i look at it like getting a mini-massage to relieve the stress of going through all that security theater.
i read somewhere that if we were serious about security, we'd be better off hiring a couple dozen sniffer dogs per airport and letting people walk right through, but the tsa looks to me more like a national jobs program than a security force (which is fine if it didn't make travel such a hassle).
I've flown in New Zealand where you don't need to talk to anyone or go through even a metal detector before boarding. I felt safer and happier than flying in the US.
I agree with your main point, and am sorry to nit-pick, but I think that it's important: how you feel doesn't, and shouldn't, have any effect on the policy. In fact, the whole phrase 'security theatre' describes precisely the phenomenon of making (easily mollified) people feel secure instead of being secure. I am not at all saying that you are in this boat (it sounds like you're not), only that I think the word choice is very important.
I 100% agree that my feelings should be irrelevant to security policies. But the precautions taken by the TSA are completely disproportionate to the amount of risk we face while flying. It's a total joke to say that it's anything but "security theatre". That feeling of security is really all we're buying with all that money and inconvenience.
I agree; but what I meant here was that praising a different set-up for making you feel more secure risks implicitly suggesting that this feeling is the goal (rather than at best a pleasant by-product), thus playing into the whole security-theatre game.
And therein lies the rub. When rule by science is declared to be just, it leaves those trying to preserve autonomy ultimately at odds with science. (As well as corrupting science by people seeking power)
It bothers me to play on fears about radiation and sexual paranoia to get people to see that government interests diverge from theirs, and that perhaps maybe there is something wrong about eg deploying these ridiculous scanners.
But whenever I try the ideological approach, people resist applying abstract concepts to judge the concrete situation. Either they have little experience doing so, or the more erudite have merely used their intelligence to internalize all the flimsy justifications that, by common law, have destroyed any basis of this government's original charter.
I guess the analog of my initial observation applies to rule by the masses (with respect to rationalism) as well so, at least for this topic, hysteria it is.
That woman, who had a letter from the TSA saying that breast milk didn't need to go through the xray scanner, didn't have a fun time when she asked for her breast milk to not be xrayed.
I signed up for Global Entry with the Customs and Border Patrol and it definitely makes things faster and I don't have to go through the millimeter wave machines (just the traditional metal detector).
I don't even see the X-Ray machines anywhere these days. Where do they still have them? I only see the other kind, the millimeter wave or whatever they are.
And the author says the dose is really 14.76 microrem, but doesn't dispute the equivalence to flight time. So really it's equivalent to 3 minutes of flight, not just 2.
50% of trivial is still trivial.
Oh, and the author says that the margin of error on these measurements is large. So perhaps the TSA didn't lie at all, they just measured 10 microrem. Even if the margin of error is 1000% the result is still trivial.
So... basically this is non-news about a technology which isn't even in use anymore. The TSA now uses millimeter wave technology as the author is aware ("these backscatter x-rays are decommissioned and sitting in a warehouse").
There are a lot of good reasons to be concerned about the TSA's use of imaging technology. This is not one of them.