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Comment by AngryParsley | Hacker News Reader

That letter is from April. The FDA wrote a response last month: 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.

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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.)

>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?

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.

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. :)

You're only principled because you don't live in the US, and need to use air travel </sarcasm> ;-)

"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.

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.

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.

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.

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.

That's called dishonesty.

Its called politics, and as much as I hate it, thats how most stuff gets done in the real world.

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.

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.

If you're willing to say anything to make the other side look bad, why should anyone give you credence?

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.

These machines have been called, by a reputable scientist, as potentially very dangerous.

And 1 out of 5 dentists recommend sugar gum. There are enough scientists in the world that you can always find one who shares your belief. Scientific consensus is a much more reliable indicator of correct beliefs.

...nor do I particular care to present both sides of the argument.

I can think of half a dozen pieces of evidence that would change my belief about whether or not backscatter devices are safe. What evidence would you need to convince you that they are safe?

This isn't about whether they are safe or not (a subject I don't give much of anything about), but about getting them banned. If we can't get them banned for privacy issues (as they should be) but we can get them banned for something else, then I will take that.

And it was a leading scientist.

Maybe they shouldn't, but when you're going up against the kind of ruthlessness that will stop at nothing to invade your privacy by any means, limiting your angles of attack for ethical concerns might not be palatable for everyone. I'd like these machines to be banned for privacy concerns as well, but if they're banned for safety concerns that I made up, that's still better than them being put in every airport.

That's a dangerous path to go down; if we abandon factual standards or arguing issues on the legal merits, then what's left is basically just marketing. And there will always be someone who can afford better marketing.

It's like torture; one can't torture on behalf of the 'good guys' and say it's for a higher purpose, because acceptance of torture as a legitimate means of inquiry is exactly the sort of thing that divides good government from bad (this, of course, assumes one is opposed to the practice in the first place).

I think the point is that we're already at that place. These machines are only there because of what you call marketing. You may think a knife is an elegant weapon for a more civilized age, but you're still screwed if you bring one to a gunfight. It's a difficult choice.

True, but that genie has been out the bottle for thousands of years. It is called being human.

> A little fud now and then is a good thing

This, my friend, is the problem with politics and science today.(And probably all of human history, but I was going for affect.)

I would love to have a debate over the privacy issues with a population that has been thinking critically about the issues.

But until then, I have to work with what we have.

The AIT machines are 100% about politics. This is not science.

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