Good Job, Cecil - you hit about every major point in the discussion.
Two addenda:
Cesium-137 has a long halflife, and so is still around in small quantities from the old atmospheric tests. As noted, it is a calcium mimic, and is taken up by certain foods on that basis. Potatoes are an example. Luckily, the isotopes with the longer half-lives are less radioactive (which is a tautology, but many folks don’t realize it), so this is not a problem.
There is an additional factor in radiosensitivity of children: the most sensitive cells are the ones which are actively dividing. This is why the cells of the hair follicles and digestive system are affected most by exposure, such as radiation treatments; they are actively dividing. Since children are still growing, they have more actively dividing cells in their bodies than adults.
Some people aren’t effected by radiation as much as others. Everything you have stated seems to be true MacLir, I like that. I wish I could blame my baldness on radioactivity but I have to blame it on heredity.
Seven or eight years ago, there was a news item about radioactivity in milk. During the time in the 50s and 60s when the US and USSR were doing above ground nuclear weapons testing, fallout rode the winds, and Strontium 90 fell on farm grass.
As Cecil said, cows ate the hot grass and produced hot milk. Strontium 90, the news story said, has a fairly brief half-life, so milk in the grocery stores was more-or-less safe. Farm kids, though, drank milk fresh from the cows. Grown-up farm kids told me they’d often drink it still warm from the udders. That milk was still radioactive. The CDC now says those grown-up farm kids should now be more vigilant for cancer than city boys like me.