Physical Insights

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Let me put it like this…

with 3 comments

… the linear-non-threshold (LNT) hypothesis is a scientific hypothesis in almost* exactly the same sense that “Intelligent Design” is a scientific hypothesis.

* A key difference is that LNT is falsifiable, of course.

Written by Luke Weston

April 5, 2008 at 5:24 pm

3 Responses

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  1. Although the ICRP considered the LNTH a reasonable basis on which to assess the risk from radiation and to frame regulations, even they recognize there are no reliable observations of adverse health effects in humans exposed to radiation doses in the low range. The hypothesis they have said officially, is not recommended as a fact, but as a prudent assumption on which to base regulations for radiological protection.

    They have also said that, the claim that “Low-level radiation is more dangerous than high-level”, often quoted by nuclear critics, is a distortion because it omits the vital qualification “per unit dose”. At this level the argument is an academic one over relatively large differences but in very small risks. The reason that the argument continues unresolved is that the differences in absolute risk are so small that they cannot be measured in practice.

    The ICRP’s considered opinion in a 1977 publication was:

    “However, the more cautious such an assumption of linearity is, the more important it becomes to realize that it may lead to an overestimate of the radiation risks, which in turn could result in the choice of alternatives that are more hazardous than practices involving radiation exposures. Thus, in the choice of alternative practices, radiation risk estimates should be used only with great caution and with explicit recognition of the possibility that the actual risk at low doses may be lower than that implied by a deliberately cautious assumption of proportionality.”

    So even the framers of this hypothesis recognized at the time it was flawed.

    DV82XL

    April 5, 2008 at 9:14 pm

  2. DV82XL has it right.

    LNT is not like ID, a “I pulled it off my a***” hypothesis “just because it fits my fact-free bigotry”.

    LNT is a fall back assumption, a prudential hypothesis. That’s where you start when the only serious alternative is “I don’t know” and it’s easy to use in the absence of conclusive observations at low doses of anything : radiation, chemical toxins, etc.

    But yes, it’s high time that the ICRP prefaces all of its publications with that little story about turtles and hot water.

    Fifi

    April 5, 2008 at 10:09 pm

  3. Right. The LNTH isn’t a scientific hypothesis, it’s a statement of scientific ignorance and was framed from the beginning as an initial hypothesis that was expected to be refined as better data became available. What has happened is that it has become politicized to the point where no one creating regulations will challenge it for fear of being accused of putting people at risk.

    Given that regulations are written by governmental and quasi-governmental bureaucracies the chances that it will be discarded in the near future are slim.

    DV82XL

    April 6, 2008 at 3:58 am


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