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That letter is from April. The FDA wrote a response last month: http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySys

That letter is from April. The FDA wrote a response last month: http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/SecuritySystems/ucm231857.htm http://www.fda.gov/Radiation-EmittingProducts/RadiationEmitt... The recommended limit for annual dose to the skin for the general public is 50,000 µSv. The dose to the skin from one screening would be approximately 0.56 µSv when the effective dose for that same screening would be 0.25 µSv. Therefore the dose to skin for the example screening is at least 89,000 times lower than the annual limit. Most of the concerns in the letter are addressed. It's easy to spread FUD, but these devices are likely safe. Other organizations and governments have evaluated their safety independently.

eiji 16y ago
"Most" of the concerns ... ... are "likely" safe. It's a tiny line between FUD and alertness. I prefer people bring this stuff up every now and then to remind all of us to never stop questioning things.
- AngryParsley 16y ago
  It's so easy to get caught up in the halo/horn effect and try to make every fact about backscatter machines bad. But the truth is complicated. It requires weighing all evidence, not just looking at evidence that agrees with your current views. 89,000 times lower than the annual limit. I'm not a fan of the TSA or backscatter machines, but facts are not up for debate. If backscatter machines cause cancer, it would be very surprising and it would tell us something new about physics and/or biology. Also, if you worried about every risk that was as low as backscatter machines, you simply wouldn't be able to function in society. 5 minutes in a car is a 1 in 5 million chance of death.
  - mortenjorck 16y ago
    I think most would rather the use of these devices be banned on principles of their invasiveness rather than on safety concerns. Otherwise, you just get a "safer" version of the same thing in a few years.
    - tomjen3 16y ago
      Sure, but I would take getting them banned on any ground. In a few years, we will call them cancer machines again and see if we can win then. If you have a way to win on privacy issues the more power to you, but I doubt it can be done.
      - roadnottaken 16y ago
        That's called dishonesty.
        tomjen3 16y ago
        Its called politics, and as much as I hate it, thats how most stuff gets done in the real world.
    - AngryParsley 16y ago
      That's a different discussion. I'm just talking about safety. The scientists in the letter are just talking about safety. The FDA is just talking about safety. "Should we put these things in airports?" brings a lot more baggage with it than "Are these things safe?" I wish our opinions about backscatter devices could stay out of this discussion about their safety. I'm going to mention my opinion anyway, because otherwise people will suspect me of being on The Other Side. I think these devices are a waste of money and I don't want to be subject to them. They raise a ton of privacy concerns and make me wonder, "What's next?" But they're almost certainly safe.
tomjen3 16y ago
It does not matter if they are safe (which they aren't), it matters that they be removed. A little fud now and then is a good thing.
- usinglogin 16y ago
  Hitler: "It does not matter if the jews are good citizens (which they aren't), it matters that they be blamed for all our problems. A little fud now and then is a good thing."
  - forgottenpaswrd 16y ago
    Godwin Law, you loose the argument!! http://en.wikipedia.org/wiki/Godwin%27s_law http://en.wikipedia.org/wiki/Godwin%27s_law
  - tomjen3 16y ago
    When the machines become sentient, you may have a point. In addition, the machines are bad on privacy terms, but since the debate has been frame such that those who advocate privacy are considered suspect, we have to work with what we have and make the best of it.
- chroma 16y ago
  If you're willing to say anything to make the other side look bad, why should anyone give you credence?
  - tomjen3 16y ago
    There is a big difference between a little fud and being willing to say anything. These machines have been called, by a reputable scientist, as potentially very dangerous. I see no problem making sure everybody knows that they are dangerous, nor do I particular care to present both sides of the argument.
    - AngryParsley 16y ago
Retric 16y ago
There is some evidence that extremely low radiation do not increase your cancer risk. However, if you realize that a pilot already receives increased radiation by flying several hours a day and could average 2+ of these scanning’s a day for 30+ years you are probably adding a significant risk (compared to getting a pat down). As to passenger safety the annual dosage delivered in a short period of time is not safe. So take someone with say, a bad sun burn or a recent CAT scan and walking though those things is probably a bad idea. Also due to poor training / incompetence some people are going to be sent through these things several times and or be required to stand there while someone get's distracted. PS: The corresponding annual effective dose... and 500 mrem for the more exposed routes. (Bottollier-Depois JF et al. Assessing exposure to cosmic radiation during long-haul flights. Radiat Res 153(5 Pt. 1):526-32; 2000.)
loewenskind 16y ago
>It's easy to spread FUD, but these devices are likely safe. We have two facts here: * These machines should not be in use as they do nothing to help security and they are ripe for abuse (and have already been abused in their short time of being used) * The public is not ever going to be bothered enough by privacy concerns to actually do something about it. They would, however, do a great deal if they felt their lives depended on it. Taking these two facts into account, if a leading scientist says these things may be dangerous I would tend to take his word for it without digging into it. That sounds bad but how else can one deal with people who value convenience over what is right?
- tptacek 16y ago
  I accidentally upvoted you. There is the truth and there is falsity. None of our principles, including the one that says minimum wage security workers shouldn't be looking at us naked, mean anything if we can't look each other in the eyes and articulate them truthfully. It is falsity that is allowing people to convince airport authorities that these machines make sense. If you want to get into the bullshitting arms race, know a priori that you will lose; those people are much better at it than you are, and they have more to gain or lose.
  - pyre 16y ago
    You're only principled because you don't live in the US, and need to use air travel </sarcasm> ;-)
  - loewenskind 16y ago
    I'm not saying to lie. I'm saying if someone with credentials comes out and says there may be health issues with these things we don't need to look any further. They shouldn't be in the airport whether they present a safety risk or not. Instead of wasting energy chasing something that doesn't change the over all outcome (finding out they're safe still doesn't mean they should be used), use that energy to research things that do matter. It's just about being efficient. :)
gammarator 16y ago
Thanks for pointing to this very thorough response which addresses the concerns of the letter. I don't think the authors of the letter are spreading FUD, however: they're asking for more information about the means by which the dose is being calculated and pointing out potential health consequences of the lower-energy beam in skin absorption: <em>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.</em> This looks like science to me, not FUD.

eiji 16y ago

"Most" of the concerns ... ... are "likely" safe. It's a tiny line between FUD and alertness. I prefer people bring this stuff up every now and then to remind all of us to never stop questioning things.

AngryParsley 16y ago
It's so easy to get caught up in the halo/horn effect and try to make every fact about backscatter machines bad. But the truth is complicated. It requires weighing all evidence, not just looking at evidence that agrees with your current views. 89,000 times lower than the annual limit. I'm not a fan of the TSA or backscatter machines, but facts are not up for debate. If backscatter machines cause cancer, it would be very surprising and it would tell us something new about physics and/or biology. Also, if you worried about every risk that was as low as backscatter machines, you simply wouldn't be able to function in society. 5 minutes in a car is a 1 in 5 million chance of death.
- mortenjorck 16y ago
  I think most would rather the use of these devices be banned on principles of their invasiveness rather than on safety concerns. Otherwise, you just get a "safer" version of the same thing in a few years.
  - tomjen3 16y ago
    Sure, but I would take getting them banned on any ground. In a few years, we will call them cancer machines again and see if we can win then. If you have a way to win on privacy issues the more power to you, but I doubt it can be done.
    - roadnottaken 16y ago
      That's called dishonesty.
      - tomjen3 16y ago
        Its called politics, and as much as I hate it, thats how most stuff gets done in the real world.
  - AngryParsley 16y ago
    That's a different discussion. I'm just talking about safety. The scientists in the letter are just talking about safety. The FDA is just talking about safety. "Should we put these things in airports?" brings a lot more baggage with it than "Are these things safe?" I wish our opinions about backscatter devices could stay out of this discussion about their safety. I'm going to mention my opinion anyway, because otherwise people will suspect me of being on The Other Side. I think these devices are a waste of money and I don't want to be subject to them. They raise a ton of privacy concerns and make me wonder, "What's next?" But they're almost certainly safe.

tomjen3 16y ago

It does not matter if they are safe (which they aren't), it matters that they be removed. A little fud now and then is a good thing.

usinglogin 16y ago
Hitler: "It does not matter if the jews are good citizens (which they aren't), it matters that they be blamed for all our problems. A little fud now and then is a good thing."
- forgottenpaswrd 16y ago
  Godwin Law, you loose the argument!! http://en.wikipedia.org/wiki/Godwin%27s_law http://en.wikipedia.org/wiki/Godwin%27s_law
- tomjen3 16y ago
  When the machines become sentient, you may have a point. In addition, the machines are bad on privacy terms, but since the debate has been frame such that those who advocate privacy are considered suspect, we have to work with what we have and make the best of it.
chroma 16y ago
If you're willing to say anything to make the other side look bad, why should anyone give you credence?
- tomjen3 16y ago
  There is a big difference between a little fud and being willing to say anything. These machines have been called, by a reputable scientist, as potentially very dangerous. I see no problem making sure everybody knows that they are dangerous, nor do I particular care to present both sides of the argument.
  - AngryParsley 16y ago

Retric 16y ago

There is some evidence that extremely low radiation do not increase your cancer risk. However, if you realize that a pilot already receives increased radiation by flying several hours a day and could average 2+ of these scanning’s a day for 30+ years you are probably adding a significant risk (compared to getting a pat down). As to passenger safety the annual dosage delivered in a short period of time is not safe. So take someone with say, a bad sun burn or a recent CAT scan and walking though those things is probably a bad idea. Also due to poor training / incompetence some people are going to be sent through these things several times and or be required to stand there while someone get's distracted. PS: The corresponding annual effective dose... and 500 mrem for the more exposed routes. (Bottollier-Depois JF et al. Assessing exposure to cosmic radiation during long-haul flights. Radiat Res 153(5 Pt. 1):526-32; 2000.)

loewenskind 16y ago

>It's easy to spread FUD, but these devices are likely safe. We have two facts here: * These machines should not be in use as they do nothing to help security and they are ripe for abuse (and have already been abused in their short time of being used) * The public is not ever going to be bothered enough by privacy concerns to actually do something about it. They would, however, do a great deal if they felt their lives depended on it. Taking these two facts into account, if a leading scientist says these things may be dangerous I would tend to take his word for it without digging into it. That sounds bad but how else can one deal with people who value convenience over what is right?

tptacek 16y ago
I accidentally upvoted you. There is the truth and there is falsity. None of our principles, including the one that says minimum wage security workers shouldn't be looking at us naked, mean anything if we can't look each other in the eyes and articulate them truthfully. It is falsity that is allowing people to convince airport authorities that these machines make sense. If you want to get into the bullshitting arms race, know a priori that you will lose; those people are much better at it than you are, and they have more to gain or lose.
- pyre 16y ago
  You're only principled because you don't live in the US, and need to use air travel </sarcasm> ;-)
- loewenskind 16y ago
  I'm not saying to lie. I'm saying if someone with credentials comes out and says there may be health issues with these things we don't need to look any further. They shouldn't be in the airport whether they present a safety risk or not. Instead of wasting energy chasing something that doesn't change the over all outcome (finding out they're safe still doesn't mean they should be used), use that energy to research things that do matter. It's just about being efficient. :)

gammarator 16y ago

Thanks for pointing to this very thorough response which addresses the concerns of the letter. I don't think the authors of the letter are spreading FUD, however: they're asking for more information about the means by which the dose is being calculated and pointing out potential health consequences of the lower-energy beam in skin absorption: <em>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.</em> This looks like science to me, not FUD.