1. This is important to realize that our cells are under constant stress from non-nuclear sources. Thanks Rod. That is a new insight. I updated my blog post The Time Is Right for Discussing Hormesis with this post and some of your other posts. I also added three excellent diagrams that help sort out the radiation levels and there effects on humans.

    1. @Rick
      Radiation damages far more if it hits at the moment of cell division.
      So stable organism’s (a.o. older persons) are far less vulnerable than organsim’s that are developing fast/

      So Scherb at al showed with exceptional significance that even low level radiation below 0.5mSv/year already enhance the rate of stillbirth, congenital malformations, Down syndrome, peri-natal death, etc.

      The stillbirth rate rising at a staggering ~60% per 1mSv/year rise!
      Btw. this is in line with medical practise to avoid any radiation for pregnant women.

  2. The problem is that LNT cannot be falsified (or verified) due to the way it is stated, so arguing over it is a waste of time. What is needed is a solid mechanistic model that is not based of vague statistical foundations. The same is true of the radiation hormesis model, at the moment it too develops out of statistical evidence. While both sides can provide a plausible mechanism explaining what they think is happening on the cellular level, hard empirical proof is lacking.

    The debate is becoming somewhat sterile at this point and something needs to be done to break the logjam. But guaranteed, no regulator is going to budge on the counter-evidence tabled to date against LNT.

  3. Ionizing radiation might break a bond in a protein in a human cell, with no long lasting effect. Rarely, this might even cause cell death. Cell death and regrowth occurs naturally in humans, with a characteristic time of a few months, varying by organ. Even more rarely, the ionizing radiation might break a bond in a DNA strand. But DNA is the DOUBLE HELIX, with each protein paired to matching one in the other helix. This redundancy of information allows enzymes to repair broken DNA strands. DNA strand breaks are most commonly due to oxygen ions, not ionizing radiation. (This is the motivation for taking antioxidant vitamins.) The average DNA break and repair rate is about 1 per second PER CELL. There are about 100 trillion cells in the human body.

    During cell division, which is more frequent during growth, the strands are separated, so the redundancy is lost and the repair rate is less. (This is the motivation for more caution for exposure of children and fetuses.)

  4. The LNT assumption has been falsified repeatedly from the time that it was created in the mid-1950s. What has been going on is “willful blindness” of the ever-mounting scientific evidence that contradicts it. The LNT assumption is politicized science designed to create/perpetuate the scare of even the smallest levels of (human-made) radiation. See the commentary, available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2939692/pdf/drp-08-378.pdf

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