10 ms·

More tellingly, on an average two-hour flight, you'd receive about 100 times the radiation from a single scan. But, by using the transitive property, you're mo

by zbanks 16y ago

More tellingly, on an average two-hour flight, you'd receive about 100 times the radiation from a single scan. But, by using the transitive property, you're more likely to die from radiation at flying altitudes than from a terrorist attack on said airplane. EDIT: Sorry, I forgot to include the link: http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effects http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effect... Which comes from: http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/radexp.html http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/radexp.htm... Which explicitly states its references.

deleted 16y ago
[deleted]
maninthemirror 16y ago
You are understating the risk from backscatter radiation. Because the radiation is sent in a burst, and targets skin tissue, the DNA damage may be far greater than a similar dose of cosmic radiation. You are also assuming that the backscatter machines are functioning properly and aren't overdosing people.
- naz 16y ago
  A single backscatter X-ray scan gives a radiation dose of 0.009 mrems, about the same as eating a banana. http://en.wikipedia.org/wiki/Banana_equivalent_dose http://en.wikipedia.org/wiki/Banana_equivalent_dose Don't get me wrong, I'm opposed to the scanners as much as anyone for privacy reasons and general pointlessness. But I'm seeing a lot of bad science thrown around here.
  - daten 16y ago
    You're not comparing bananas to bananas. As I understand, the limited information that has been publicly released about the backscatter machines is a useless measurement when you take into account how they actually work. You can't apply a standard measurement from a medical x-ray machine that targets a small part of your body using one technique to a different machine that targets your entire body using a different technique. So the two problems are: 1. You don't have good numbers to even evaluate how dangerous they are, many evaluations, including possibly the article above, are useless because they don't have the real data to compare to. 2. The radiation exposure from a banana also effects your body differently than a medical x-ray machine which is in turn different from a backscatter machine targeting your entire body. I'm not saying people aren't trying to evaluate the actual risk in good faith. I'm saying they're skipping the step where we get useful numbers from the manufacturer of the machine to even apply good science to. Edit: by "whole body" I mean "whole surface of your body" since it's concentrated on your skin
  - travisp 16y ago
    While I might agree that the worried about an X-ray scan are overblown (I assume that is your position), that number is looking at a whole body number. Part of the argument is that the amount may be significantly higher because the dose is concentrated near the surface of the skin, rather than across the whole body like cosmic ray and chest X-ray exposure.
    - yummyfajitas 16y ago
      So instead of being equivalent to eating a banana, it's probably equivalent to mashing one up and using it as skin cream. In other news, millions of small children who enjoy playing with food exposed to RADIATION! Are bananas safe for your children?
- Confusion 16y ago
  Because the radiation is sent in a burst, [..] the DNA damage may be far greater than a similar dose of cosmic radiation. People keep repeating that, but it is not simply true. DNA can get damaged when a single photon excites an electron and consequently influences the molecular structure. The chances of multiple photons operating on the same electron at the same time, even in cases of a radiation burst, are negligible. The person is affected by the same number of photons, which results in the same number of chances of electrons being excited. The number of excited electrons will be equal and the resulting damage will be equal. Now it may matter that the damage is more localized in both space and time, but no one has shown this. Firstly space: spreading the radiation over only the surface, for instance 1/10th of the body (remember that surface times a small depth is always a relatively large part of a volume), means 10 times as much damage. But if the average amount of damage in the skin was one broken bond per 1000 cells, it will now be one broken bond per 100 cells. As the repair takes place per cell, that doesn't change anything for the total chances to get cancer. Only if the amount of damage in a single cell, and close enough to each other to be relevant, changes, then this type of operation may pose a problem. Secondly for time: everything depends on the amount of time it takes a cell to repair DNA damage. If the average time of repair takes 3 seconds, then during a flight, some damage will be repaired before other damage takes place. The backscatter machine delivers its dose faster and damage may accumulate. However, if repair takes 30 minutes on average, the difference is again neglible. The point is not that I know the numbers: the point is that people making claims don't know them. They are just claiming things that seem to make sense to them, when they draw an analogy with a car crash or something. They don't understand what is actually involved.
deleted 16y ago
[deleted]
aphyr 16y ago
This comparison is meaningless. The risk of cancer is caused by DNA errors. Your cells are constantly checking and repairing your DNA for mutations and damage. They can usually repair or detect a low error rate, like the kind you get from living at high altitude, in a house with a minor radon source, or flying on a plane. What they can't deal with as well is a sudden burst of many errors. Backscatter X-ray scanners deliver their entire dose to a tissue region in a few microseconds. That's the kind of exposure we're talking about, and it has an entirely different biological impact.
- Confusion 16y ago
  Where 'an entirely different biological impact' may just as well mean 'no impact at all': it may even turn out to prevent melanomas. While everyone is busy losing themselves in radiation hysteria, where facts are only guessed at, the government is laughing their ass off, because everyone lost sight of the actual problem: that these machines are assumed to improve safety in the first place. The radiation scare is an enormous red herring that mainly harms the public perception of 'radiation', that wasn't too good to begin with, for all the wrong reasons.
  - aphyr 16y ago
    We know that short-term small doses of X rays results in increased probability of developing skin cancer. We know that prolonged exposure to low-level radiation sources increases your probability of developing skin cancer. We know that acute high doses of ionizing radiation leads to your skin falling off. Skin cancers are abnormally elevated in radiologists, survivors of Hiroshima who experienced even relatively low doses, radioisotope miners, and people who are treated with X rays for skin conditions. I'll hazard a guess here and say there's close to zero probability that backscatter machines are lowering your risk of cancer. Don't get me wrong: I love radiation. I think Cherenkov glow is the coolest thing about working in a reactor. I've handled more sources than I probably should have by this point in my life. At the same time, we should be honest that there is probably a small risk, and it is probably higher than currently stated.
    - 16y ago

by zbanks 16y ago

deleted 16y ago

[deleted]

maninthemirror 16y ago

You are understating the risk from backscatter radiation. Because the radiation is sent in a burst, and targets skin tissue, the DNA damage may be far greater than a similar dose of cosmic radiation. You are also assuming that the backscatter machines are functioning properly and aren't overdosing people.

naz 16y ago
A single backscatter X-ray scan gives a radiation dose of 0.009 mrems, about the same as eating a banana. http://en.wikipedia.org/wiki/Banana_equivalent_dose http://en.wikipedia.org/wiki/Banana_equivalent_dose Don't get me wrong, I'm opposed to the scanners as much as anyone for privacy reasons and general pointlessness. But I'm seeing a lot of bad science thrown around here.
- daten 16y ago
  You're not comparing bananas to bananas. As I understand, the limited information that has been publicly released about the backscatter machines is a useless measurement when you take into account how they actually work. You can't apply a standard measurement from a medical x-ray machine that targets a small part of your body using one technique to a different machine that targets your entire body using a different technique. So the two problems are: 1. You don't have good numbers to even evaluate how dangerous they are, many evaluations, including possibly the article above, are useless because they don't have the real data to compare to. 2. The radiation exposure from a banana also effects your body differently than a medical x-ray machine which is in turn different from a backscatter machine targeting your entire body. I'm not saying people aren't trying to evaluate the actual risk in good faith. I'm saying they're skipping the step where we get useful numbers from the manufacturer of the machine to even apply good science to. Edit: by "whole body" I mean "whole surface of your body" since it's concentrated on your skin
- travisp 16y ago
  While I might agree that the worried about an X-ray scan are overblown (I assume that is your position), that number is looking at a whole body number. Part of the argument is that the amount may be significantly higher because the dose is concentrated near the surface of the skin, rather than across the whole body like cosmic ray and chest X-ray exposure.
  - yummyfajitas 16y ago
    So instead of being equivalent to eating a banana, it's probably equivalent to mashing one up and using it as skin cream. In other news, millions of small children who enjoy playing with food exposed to RADIATION! Are bananas safe for your children?
Confusion 16y ago
Because the radiation is sent in a burst, [..] the DNA damage may be far greater than a similar dose of cosmic radiation. People keep repeating that, but it is not simply true. DNA can get damaged when a single photon excites an electron and consequently influences the molecular structure. The chances of multiple photons operating on the same electron at the same time, even in cases of a radiation burst, are negligible. The person is affected by the same number of photons, which results in the same number of chances of electrons being excited. The number of excited electrons will be equal and the resulting damage will be equal. Now it may matter that the damage is more localized in both space and time, but no one has shown this. Firstly space: spreading the radiation over only the surface, for instance 1/10th of the body (remember that surface times a small depth is always a relatively large part of a volume), means 10 times as much damage. But if the average amount of damage in the skin was one broken bond per 1000 cells, it will now be one broken bond per 100 cells. As the repair takes place per cell, that doesn't change anything for the total chances to get cancer. Only if the amount of damage in a single cell, and close enough to each other to be relevant, changes, then this type of operation may pose a problem. Secondly for time: everything depends on the amount of time it takes a cell to repair DNA damage. If the average time of repair takes 3 seconds, then during a flight, some damage will be repaired before other damage takes place. The backscatter machine delivers its dose faster and damage may accumulate. However, if repair takes 30 minutes on average, the difference is again neglible. The point is not that I know the numbers: the point is that people making claims don't know them. They are just claiming things that seem to make sense to them, when they draw an analogy with a car crash or something. They don't understand what is actually involved.

deleted 16y ago

[deleted]

aphyr 16y ago

This comparison is meaningless. The risk of cancer is caused by DNA errors. Your cells are constantly checking and repairing your DNA for mutations and damage. They can usually repair or detect a low error rate, like the kind you get from living at high altitude, in a house with a minor radon source, or flying on a plane. What they can't deal with as well is a sudden burst of many errors. Backscatter X-ray scanners deliver their entire dose to a tissue region in a few microseconds. That's the kind of exposure we're talking about, and it has an entirely different biological impact.

Confusion 16y ago
Where 'an entirely different biological impact' may just as well mean 'no impact at all': it may even turn out to prevent melanomas. While everyone is busy losing themselves in radiation hysteria, where facts are only guessed at, the government is laughing their ass off, because everyone lost sight of the actual problem: that these machines are assumed to improve safety in the first place. The radiation scare is an enormous red herring that mainly harms the public perception of 'radiation', that wasn't too good to begin with, for all the wrong reasons.
- aphyr 16y ago
  We know that short-term small doses of X rays results in increased probability of developing skin cancer. We know that prolonged exposure to low-level radiation sources increases your probability of developing skin cancer. We know that acute high doses of ionizing radiation leads to your skin falling off. Skin cancers are abnormally elevated in radiologists, survivors of Hiroshima who experienced even relatively low doses, radioisotope miners, and people who are treated with X rays for skin conditions. I'll hazard a guess here and say there's close to zero probability that backscatter machines are lowering your risk of cancer. Don't get me wrong: I love radiation. I think Cherenkov glow is the coolest thing about working in a reactor. I've handled more sources than I probably should have by this point in my life. At the same time, we should be honest that there is probably a small risk, and it is probably higher than currently stated.
  - 16y ago