How negligible is negligible?

SNT and the Union of Concerned Scientists

Figure 1. Lucy and the meaning of the word negligible

Growing up in a traditional Catholic family, I always had a problem with sermons. The latin part of the Mass was no fun; but it was kind of a cool ritual. Yeah, you wanted to get through it as quickly as possible, but it was intriguing to think you were mouthing pretty much the same words your ancestors had for nearly 2000 years.

But the sermons were in everyday boring English. Occasionally a priest would put a slightly different twist on things, but mostly it was the same exhortations over and over again. I'm pretty sure Catholic priests have taken a vow against oratory. I never heard any thundering denunciations of the wicked at Mass. Not a hint of MLK-like cadence. Almost always it was relief to get back to reciting latin again.

But now I sympathize with the poor priests. A consistent theme of the Gordian Knot News is the worst sin an anti-LNTer can commit is to claim that there is a threshold below which there is zero harm. This admonition appear to have stuck with the choir no better than most priestly advice has with me.

If that's the case, your penance is to go back and read the parable of Lucy. I won't repeat it here. But perhaps some exegesis would be helpful. Perhaps these recidivists do not appreciate the magnitude of the difference between LNT and SNT at low dose rates. Table 1 shows the Union of Concerned Scientists (UCS) analysis of the Chernobyl release. The UCS is a particularly obnoxious group of elitists, well worthy of thundering denunciation had I the skills. Ask the people who lived around Yankee Rowe. But for now let's accept their numbers for the Chernobyl doses.

Table 1. UCS estimate of Chernobyl cancer deaths excluding thyroid.

Even in a release as large as Chernobyl, dose rates above those in high background areas were confined to a few hundred thousand people.\cite{cardis-1996} However, the number of people exposed to a slightly elevated dose rates was in the hundreds of millions. LNT claims more cancers among the slightly elevated group than among those who have received unnaturally high dose rates. The usual work around is to gin up an arbitrary cut off, and ignore doses below that cut off. Such an inconsistent procedure persuades no one, nor should it. The lunacy of a radiation harm model that you can't use to predict radiation harm when it is needed should be obvious to everyone.

At least, the UCS does LNT right.\cite{ucs-2011} Table 1 compares their analysis of cancer deaths due to Chernobyl with an SNT based analysis using the same numbers.¹ In order to apply SNT to the UCS Chernobyl numbers, we must estimate the dose rate profiles. For the liquidators I have assumed all the dose was received in two weeks. For the evacuees, I used one day. For the other groups, I assumed the period was a year, spread evenly. This should be conservative, at least for the Other N. Hemisphere group.² By the time the plume reached these people, almost all the radioiodine would be gone. Most of the dose would be cesium with a 2 to 30 year half-life.

For present purposes, I want to call your attention to the bottom line of Table 1. LNT claims 3420 eventual deaths among 3 billion people. SNT claims 0.002 deaths among 3 billion people.³ Some members of the choir may not think one in a trillion is negligible; but I guarantee you Joe Sixpack does.

1. The UCS liquidator numbers are clearly inflated. The numbers from the All Union Distribution Register are 1986: 138,390, 1987: 85,556, 1988: 26,134, 1989: 43,020. The UCS numbers are probably based on the number of people who qualified for liquidator status. Liquidators received better medical care and a number of perks such as free public transit rides. The politically connected had means of convincing local Party officials they should be given the necessary documentation. 200,000 of the UCS liquidators were nowhere near Chernobyl. The UCS knew or should have known the actual numbers.

2. To do SNT correctly, I would need the individual dose rate profiles. An SNTer can't use group averages, as I have. But the errors at least for the Other N. Hemisphere group, won't affect the overall conclusion.

3. It is not just that the SNT dose response curve is below the LNT response for repair period doses below about 180 mSv. Far more importantly, SNT divides the dose-rate profile into daily doses and computes the unrepaired damage (aka harm) for each day’s dose separately. The daily doses are orders of magnitude smaller than the total dose upon which LNT bases its harm. The combined result is that the SNT harm for the Other N. Hemisphere group is 17 million times less than the LNT harm.