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You get a pretty decent radiation dose from flying around high in the atmosphere too. From what I have read the crossover point where you absorb more x-ray radi

You get a pretty decent radiation dose from flying around high in the atmosphere too. From what I have read the crossover point where you absorb more x-ray radiation in the flight than the scanners is about an hour and a half. See here for a bunch of things to read (http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effects http://en.wikipedia.org/wiki/Backscatter_X-ray#Health_effect...). According to this page, 42 minutes of ordinary living is sufficient to give you a similar dose of ionizing radiation compared to the backscatter machines. It's certainly possible that the FDA is lying to us, but it seems more likely that these machines are indeed harmless. Sounds to me like the people saying "I avoid things until I'm sure they don't cause cancer" are throwing science to the wind and embracing a line of thought they wouldn't if they didn't already have some other reason for opposition.

kreneskyp 16y ago
Radiation is cumulative. Saying that you will absorb more radiation in flight is not a justification for accepting radiation from another source. You will still absorb more total radiation. It's a lot easier to avoid the scanner, than it is to find an alternate mode of transportation across long distances.
- jamesaguilar 16y ago
  In one situation, large quantities of X cause no visible concern to people. In another situation, much smaller quantities of X cause serious outcry, even when no harmful effects from those smaller quantities have been demonstrated over twenty years of study. I suppose it's possible for someone to be genuinely concerned over these very small quantities of radiation. But it strikes me that for the average person what underlies the panic is 1. a counter-factual belief that more health-harm is done by a new technology than actually is, 2. a diversionary appeal to concern for safety when health risks are not really a significant negative of a new technology. This happens in all kinds of areas. Artificial sweeteners, GMO foods, irradiated meat products, and vaccines have all fought or are fighting this battle. The only reason this type of thinking is given a pass here or anywhere reasonable people congregate is because the community is so opposed to the technology for other reasons.
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CWuestefeld 16y ago
According to what I've read, the energy of the radiation prevents it from penetrating deeply (indeed, the Compton effect backscatter at the surface is the whole point of it). This might sound like a good thing, but it also means that the radiation isn't "diluted" over the full mass of your body. The damaging effects will be localized to -- and concentrated within -- the skin and shallower tissues. So those organs affected are getting a dose that's disproportionately much higher than the guidelines for full-body dosage considers.
- yummyfajitas 16y ago
  This argument betrays a lack of understanding of radiation physics. Think of each cell in your body as a dice. When a cell is hit by radiation, the dice is rolled - you get cancer if any dice comes up 6 (these are billion-sided dice). The radiation dose is the number of dice rolls you need to make. Now, under which circumstance is a roll of 6 more likely? If you roll 100 dice 1 time each (traditional x-ray), or 1 dice 100 times (backscattered xray)?
  - Dylan16807 16y ago
    Smaller doses over time are safer than a large dose. Time to fix things up. Concentrating the radiation has a negative effect. Edit: Maybe this is incorrect when it comes to cancer risk, but I had the impression it still mattered, with multiple impacts in the same area of DNA causing things to be more likely to permanently break. Unless that is extremely unlikely to happen at all at this level of dose. Still, these machines are probably not particularly harmful.
    - yummyfajitas 16y ago
      When radiation causes a significant amount of cell death, yes. I.e., if you are going to have 2-3% of your cells killed (by heat, radiation, alchohol, whatever), it's better if it happens slowly over time than all at once. Backscattered X-rays are not remotely near that point. edit: Just want to respond to this: I had the impression it still mattered, with multiple impacts in the same area of DNA causing things to be more likely to permanently break. This is called the multiphoton effect. It's real, but it's more important for radiation by low frequency radiation (e.g., cell phone microwaves). You can observe this in gases with high powered lasers or microwave resonating cavities. Weird things happen in this regime, such as stabilization (more radiation -> less ionization). I suppose you could have molecular effects from multiple photons (e.g., one photon damages the DNA, a second damages the repair mechanism), but this is vanishingly unlikely at the doses we are discussing.

kreneskyp 16y ago

Radiation is cumulative. Saying that you will absorb more radiation in flight is not a justification for accepting radiation from another source. You will still absorb more total radiation. It's a lot easier to avoid the scanner, than it is to find an alternate mode of transportation across long distances.

jamesaguilar 16y ago
In one situation, large quantities of X cause no visible concern to people. In another situation, much smaller quantities of X cause serious outcry, even when no harmful effects from those smaller quantities have been demonstrated over twenty years of study. I suppose it's possible for someone to be genuinely concerned over these very small quantities of radiation. But it strikes me that for the average person what underlies the panic is 1. a counter-factual belief that more health-harm is done by a new technology than actually is, 2. a diversionary appeal to concern for safety when health risks are not really a significant negative of a new technology. This happens in all kinds of areas. Artificial sweeteners, GMO foods, irradiated meat products, and vaccines have all fought or are fighting this battle. The only reason this type of thinking is given a pass here or anywhere reasonable people congregate is because the community is so opposed to the technology for other reasons.

deleted 16y ago

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CWuestefeld 16y ago

According to what I've read, the energy of the radiation prevents it from penetrating deeply (indeed, the Compton effect backscatter at the surface is the whole point of it). This might sound like a good thing, but it also means that the radiation isn't "diluted" over the full mass of your body. The damaging effects will be localized to -- and concentrated within -- the skin and shallower tissues. So those organs affected are getting a dose that's disproportionately much higher than the guidelines for full-body dosage considers.

yummyfajitas 16y ago
This argument betrays a lack of understanding of radiation physics. Think of each cell in your body as a dice. When a cell is hit by radiation, the dice is rolled - you get cancer if any dice comes up 6 (these are billion-sided dice). The radiation dose is the number of dice rolls you need to make. Now, under which circumstance is a roll of 6 more likely? If you roll 100 dice 1 time each (traditional x-ray), or 1 dice 100 times (backscattered xray)?
- Dylan16807 16y ago
  Smaller doses over time are safer than a large dose. Time to fix things up. Concentrating the radiation has a negative effect. Edit: Maybe this is incorrect when it comes to cancer risk, but I had the impression it still mattered, with multiple impacts in the same area of DNA causing things to be more likely to permanently break. Unless that is extremely unlikely to happen at all at this level of dose. Still, these machines are probably not particularly harmful.
  - yummyfajitas 16y ago
    When radiation causes a significant amount of cell death, yes. I.e., if you are going to have 2-3% of your cells killed (by heat, radiation, alchohol, whatever), it's better if it happens slowly over time than all at once. Backscattered X-rays are not remotely near that point. edit: Just want to respond to this: I had the impression it still mattered, with multiple impacts in the same area of DNA causing things to be more likely to permanently break. This is called the multiphoton effect. It's real, but it's more important for radiation by low frequency radiation (e.g., cell phone microwaves). You can observe this in gases with high powered lasers or microwave resonating cavities. Weird things happen in this regime, such as stabilization (more radiation -> less ionization). I suppose you could have molecular effects from multiple photons (e.g., one photon damages the DNA, a second damages the repair mechanism), but this is vanishingly unlikely at the doses we are discussing.