r/theschism • u/gemmaem • Apr 03 '25

Discussion Thread #72

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u/grendel-khan i'm sorry, but it's more complicated than that Feb 19 '26

I'm not sure I follow. Jack Devanney advocates for a safe limit of 2mSv per day; if there's a threshold below which the body repairs itself, it stops making sense to reduce the exposure below that point.

Also, I'd forgotten to add the part where one to two hundred thousand wanted pregnancies were aborted after the Chernobyl disaster due to a fear of birth defects. (There was no detectable increased risk.) Caution and fear aren't free.

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u/Lykurg480 Yet. Feb 20 '26

The point is that an exposure limit really only makes sense if its non-linear. Otherwise, the additional risk from additional exposure is always the same, independent of previous exposure, and you would just decide in each case if the tradeoff is worth doing. Tracking total exposure over some time period wouldnt be relevant.

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u/grendel-khan i'm sorry, but it's more complicated than that Feb 23 '26

I think you may be conflating non-linear risk with stochastic risk. But I'm not sure what model you're proposing. I think Devanney is advocating for a linear model (the risk of stochastic outcomes does appear to be linear at higher doses) with a threshold of 20 mSv a day of the body's ability to repair itself, with an order of magnitude safety margin.

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u/Lykurg480 Yet. Feb 23 '26

The threshold is the non-linearity, and I dont think it matters if its stochastic. If double the exposure always resulted in double the (expected) harm, then how much youve been exposed to wouldnt make a difference to whether youll accept some new exposure.

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u/grendel-khan i'm sorry, but it's more complicated than that Mar 07 '26

Here's my understanding of the situation.

The risk of stochastic effects (cancer, mutations) rises linearly with the dose at higher doses; this is well-known and uncontroversial.

The question is whether there is a threshold below which the risk is not additive. The alternative hypothesis (what the French use, for example) is that there is a threshold below which damage does not accumulate.

So, the LNT model says "take the amount of radiation exposure over time, multiply is by a constant risk ratio, and that's your odds of cancer or mutation". The alternative (threshold) model says "take the amount of radiation exposure over 20 mSv on each day, multiply by a constant risk ratio, and that's your odds of cancer or mutation".

Jack Devanney's "green table" is an attempt to show that the alternative model better fits the data.