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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

• Confusion 16y ago
  We know that short-term small doses of X rays results in increased probability of developing skin cancer. An increase that is so minute that we don't mind the dentist or doctor X-raying us. An increase that is so minute that we would accept it, if it actually reduced our chances of dying due to a terrorist attack. The radiation is not the problem: it is the intended goal that we have no reason to believe in. We know that prolonged exposure to low-level radiation sources increases your probability of developing skin cancer Do we? Not WiFi or the low-energy spectrum of the sun. What energy is 'low' in this respect?. And how long is 'prolonged exposure'? These claims are undoubtedly true for some values of the aforementioned quoted terms, but are they relevant here? Do most of the people repeating this stuff even wonder about that? Again, the problem is a slightly increased risk. But why is that increased risk a problem in the first place? I'll hazard a guess here and say there's close to zero probability that backscatter machines are lowering your risk of cancer. And I agree. But the "we don't know for sure" argument is pretty shallow, when we accept certain risks on a daily basis and when we all know certainty doesn't exist and we all take aspirin to prevent a second heart-attack, even though a thousand doctors will argue with another thousand doctors about whether that actually works, all citing studies supporting their side, and the net effect is quite small even according to the side affirming it works.
  • aphyr 16y ago
    Preface: I totally agree with your argument that risks must be weighed against outcomes. I also believe that even if the scanning technology were totally safe, it would be objectionable on privacy grounds. I think we're going about the whole problem of security backwards. :) An increase that is so minute that we don't mind the dentist or doctor X-raying us. Actually, we do. There are good reasons we impose strict limits on your medical X-ray exposure annually, and why you wear a lead vest or use collars to protect other tissue. There's also a good reason the radiologist stands outside the other room to press the button. Two x-rays a year is not significantly mutagenic. Fifty? Then you start getting nervous. Not WiFi or the low-energy spectrum of the sun. What energy is 'low' in this respect?. And how long is 'prolonged exposure' UV exposure from solar radiation is one of the biggest melanoma risks. A few orders of magnitude up the frequency scale, X rays for far shorter durations also have mutagenic effects on skin tissue. It's possible that low-energy X rays, falling in the middle of that energy range, also cause cancer. We don't know for sure yet because we don't regularly expose people to them. (I should mention that just because the X rays are low energy does not mean their effects scale linearly. Medical X rays are well above the Compton shoulder. IIRC (not enough time to check now) they're thermalizing slowly in heavy tissues as opposed to bouncing inelastically off the surface layers. Depending on the scattering cross-section for those energies, the backscattered X rays could be more ionizing. Total conjecture... I haven't done this for a while.) Again, the problem is a slightly increased risk. But why is that increased risk a problem in the first place? You're absolutely right. We have no good characterization of the risk. Radiation biometrics is fucking hard. I only want to argue that our current risk statement is inaccurate and poorly understood (for instance, we don't even know the angular flux of these machines), and offer some potential reasons why the risk might be higher than currently stated.