It is difficult to get a man to understand something, when his salary depends on his not understanding it.[Upton Sinclair] The Gordian Knot preacher has messed up again. The single most important background radiation study is the Karunagappally cohort which compares cancer incidence in several very high dose rate villages on the Kerala coast with the cancer incidence in neighboring villages with normal background dose rates. In 2009, Nair et al published the results, of the 15 year study, Figure 1.\cite{nair-2009}
Hi, Jack - The key is in the error bars. For either of these datasets, the proper null hypothesis is that long-period exposure to low levels of radiation has no effect at all on cancer risk. Both datasets support that conclusion, but for the first one, any line from a +20% increase in risk over the dose range studied to a -20% protective effect would fall within all the (I would hope the standard) 95% error bars. For the later version, the fourth error bar barely creeps above zero. That's the one that looks like it falsifies LNT and comes close to suggesting a fairly high probability of a protective effect (>90% of the error bar is in negative territory, and it's relatively narrow compared to the higher-dose bars.
But I don't understand something about the error bars. The third (50-99) bar has nearly 10 times the person-years of the 4th, yet its error bar isn't that much narrower. I'm still of the mind the best conclusion from the data is no effect.
From concluding remarks of the Karunagappally study.\cite{amma-2021}:
"... the confidence interval obtained from the present study is much narrower than that in the previous study, suggesting a possibility that the solid cancer risk associated with the continuous exposure to low-dose rate radiation is significantly lower than that associated with acute exposure. However, such a comparison requires matching of age at exposure since the magnitude of radiation associated RRs are known to be dependent on age at exposure."
It seems as though these researchers are seeking a job for life befitting xkcd's 882 scenario. ;)
This is much like the Neel &/or Schull studies on mutational effects (next generation effects) of Hiroshima/Nagasaki survivors. The results were always expressed in terms of LNT, even though no increase was shown. Instead of saying there was no effect, they said there is no evidence of an effect larger than ??? at doses to the parents of ???. The first of these studies came out in 1956. Luckily John Boice has come out strongly saying that we should not worry about next generational effects.
The error bar at 237 mSv spans a little less than 0.2 RR. The error bar at 617 spans about 0.5 RR. I think that is close to what I would expect.
LNT isn’t science, it is religion. Unfortunately the tarot card readers are in charge and they aren’t going anywhere. Trying to convince an LNTer with data is like trying to get a cow to eat a chicken- they just aren’t interested.
"One fundamental shortcoming of the LNT model is that it does not account for natural processes that repair DNA damage. However, there is no contiguous mathematical model that estimates cancer risk for both high- and low-dose rates that incorporates what we have learned about DNA repair mechanisms and is sufficiently simple and conservative to address regulatory concerns. The author proposes a mathematical model that dramatically reduces the estimated cancer risks for low-dose rates while recognizing the linear relationship between cancer and dose at high-dose rates."
Hi, Jack - The key is in the error bars. For either of these datasets, the proper null hypothesis is that long-period exposure to low levels of radiation has no effect at all on cancer risk. Both datasets support that conclusion, but for the first one, any line from a +20% increase in risk over the dose range studied to a -20% protective effect would fall within all the (I would hope the standard) 95% error bars. For the later version, the fourth error bar barely creeps above zero. That's the one that looks like it falsifies LNT and comes close to suggesting a fairly high probability of a protective effect (>90% of the error bar is in negative territory, and it's relatively narrow compared to the higher-dose bars.
But I don't understand something about the error bars. The third (50-99) bar has nearly 10 times the person-years of the 4th, yet its error bar isn't that much narrower. I'm still of the mind the best conclusion from the data is no effect.
Could you explain this a bit simpler for those of us who are technically less gifted, including the null hypothesis bit? Thank you.
Great Work! I am not a statistician, but the data you present seems true.
From concluding remarks of the Karunagappally study.\cite{amma-2021}:
"... the confidence interval obtained from the present study is much narrower than that in the previous study, suggesting a possibility that the solid cancer risk associated with the continuous exposure to low-dose rate radiation is significantly lower than that associated with acute exposure. However, such a comparison requires matching of age at exposure since the magnitude of radiation associated RRs are known to be dependent on age at exposure."
It seems as though these researchers are seeking a job for life befitting xkcd's 882 scenario. ;)
This is much like the Neel &/or Schull studies on mutational effects (next generation effects) of Hiroshima/Nagasaki survivors. The results were always expressed in terms of LNT, even though no increase was shown. Instead of saying there was no effect, they said there is no evidence of an effect larger than ??? at doses to the parents of ???. The first of these studies came out in 1956. Luckily John Boice has come out strongly saying that we should not worry about next generational effects.
The error bar at 237 mSv spans a little less than 0.2 RR. The error bar at 617 spans about 0.5 RR. I think that is close to what I would expect.
LNT isn’t science, it is religion. Unfortunately the tarot card readers are in charge and they aren’t going anywhere. Trying to convince an LNTer with data is like trying to get a cow to eat a chicken- they just aren’t interested.
Jack, I would like to include your Figure 2 in our article on Fear of Radiation https://citizendium.org/wiki/Fear_of_radiation
We publish the clearest, most concise summary of facts on each issue, with reliable sources.
Is this figure your creation, under CC-BY-SA license, or do we need go to the original source.
I searched for amma-2021 and found the earlier study behind a paywall. I also found this article, which you might be interested in: https://journals.lww.com/health-physics/abstract/2023/06000/the_relationship_between_cancer_and_radiation__a.5.aspx
From the abstract:
"One fundamental shortcoming of the LNT model is that it does not account for natural processes that repair DNA damage. However, there is no contiguous mathematical model that estimates cancer risk for both high- and low-dose rates that incorporates what we have learned about DNA repair mechanisms and is sufficiently simple and conservative to address regulatory concerns. The author proposes a mathematical model that dramatically reduces the estimated cancer risks for low-dose rates while recognizing the linear relationship between cancer and dose at high-dose rates."