Sigholders: a dangerous heresy
Every successful doctrine has to deal with heresy. It did not take Sigmoid No Threshold long to develop one. Unfortunately, it's a pernicious heterodoxy. SNT embraces the No Threshold doctrine. It's part of SNT's name. SNT does this for two reasons:
1) The goal is to replace LNT. By embracing the No Threshold hypothesis, SNT takes away the LNTer's only defense. Just as importantly, SNT focuses the debate on the existence of our DNA repair system, which is where LNT flatly contradicts indisputable biology. SNT does not claim to be a accurate model of that repair system. It only claims that by recognizing our dose rate dependent DNA repair ability, it is a far better model than LNT, multiple orders of magnitude better when a dose is spread over many repair periods. SNT focuses the argument on LNT's fundamental error.
2) A less conservative model is unnecessary. If SNT replaced LNT for regulatory purposes, the policy implications are such that nuclear power could be regulated like other highly beneficial and potentially hazardous activities. We could have should-cost nuclear.
But some choristers have decided we must do better. These people claim to accept SNT, but translate the SNT origin to a positive daily dose. They accept the SNT process of dividing the dose rate profile into repair periods, and treating each repair period separately; but insist that the repair period response have a threshold. I call these people sigholders.
Most sigholders translate the origin by average background daily dose or something smaller, sometimes under the Below Regulatory Concern rubric. A sigholder might claim that there is zero harm up to a daily dose of 0.01 mSv. But above this magic number, regular SNT takes over.
Sigmoid No Threshold but with a threshold? This is both oxymoronic, and just plain moronic. They have robbed SNT of its greatest strength, which is focusing the debate on LNT's preposterous claim that our bodies don't automatically repair radiation damage. The sigholder throws us back into interminable wrangling about the existence of a threshold. The grifters will call for more research. Meanwhile, LNT reigns.
And for what? The SNT cancer mortality associated with a daily dose of 0.01 mSv is 9.31e-12. If you experienced that dose every day in a 80 year life, your cancer mortality would be 2.7e-8 or 0.00000027. Your Lost Life Expectancy would be about 1.7 minutes.1 Talk about selling your birthright for a mess of pottage.2 They are throwing away SNT's greatest strength to claim that a risk that any reasonable person would deem negligible does not exist. And it's only the reasonable people that are our targets. The unreasonable are by definition unpersuadable. The sigholder throws away the key to getting SNT adopted to go after people who were never going to listen to him anyway.
At the other extreme, one sigholder puts the No Threshold threshold at 20 mSv/d. He calls this an "upgraded SNT" and an "improved SNT". This threshold appears to be based on a misreading of the Green Table, which claims that with one exception --- a dial painter whose dose rate profile peaked at 16 mSv/d as best as we can tell --- we have not reliably detected clinical cancer at dose rates below 20 mSv/d, even when those dose rates were suffered for decades.
But the Green Table in no way claims there was no harm at dose rates below 20 mSv/d. In fact, we can be confident the bones of the dial painters who incurred 10 mSv/d for a decade or more would show some deterioration if examined carefully enough. That's harm by any reasonable definition. It just so happened that one lady who got less than 20 mSv/d lived long enough (probably into her 80's) so that her harm became clinical.3
The 20 mSv/d threshold is irresponsible. And by coupling this nutty proposal with SNT, this heretic has done irreparable damage to our efforts to replace LNT with SNT. Standard SNT is a serious effort to replace LNT. The sigholders are not only oxymoronic. They are sabotaging this effort. If you are going to propose a threshold model, you have no right to call it an SNT model. You must not do so.
0.01 mSv/d (3.6 mSv/y) happens to be slightly above the average background dose rate in the US.
In a nuclear power plant release, this sigholder adjustment changes nothing. You can reduce all the daily doses at Fukushima by 0.01 mSv and you will see no significant difference in total Lost Life Expectancy nor UCert compensation.
SNT is consistent with this slow build up of harm.
Models don’t need to be correct, they just need to be useful. Engineers use known incorrect models all the time to design things that work.
The whole point of the sigmoid curve you have developed is that it can be simply calculated but is not statistically different than zero at low doses. Then exposures can be translated simply into life lost time or increased cancer incidence and then there can be all sorts of thresholds placed on those model outputs as part of a policy response so no threshold is needed in the model itself.
The first 15 minutes of LLE are free, above that we compensate you for your time seems a decent framework to me, but of course lawyers would bill for less…
What's a sigholder, can't find a definition.