"Breeze block"

There can be more than enough to do yourself damage.

Perhaps sunstroke some years back accounts for your problem.

Complete and utter bollocks. Do you seriously believe an animal (as in us) would have evolved to not cope with it's natural surroundings?

Sunstroke doesn't cause anything like what you're thinking of. Don't give up the day job, your humour isn't good enough for standup.

Skin doesn't go red straight away.

"Radiation! Yes, indeed. You hear the most outrageous lies about it. Half-baked goggle-box do-gooders telling everybody it's bad for you. Pernicious nonsense!"

Do any plants concentrate specifically the radioactive isotopes of elements that have those and non-radioactive isotopes, or do they just concentrate certain elements? (I can see how the second happens; the first seems a bit odd to me.)

I think you are probably correct. The point is that all isotopes of uranium and thorium are radioactive.

Just, in the case of U238 and thorium, not very....

Good to know you've investigated what did cause it. Care to share your conclusions? So others can take steps to avoid it.

The answer appears to be "Yes".

Well having ploughed through a lot of bollocks, teh answer appers to be for heavier elements 'no one actually knows'

Only by accident. Different isotopes of the same element have differing numbers of neutrons in the nucleus of each atom (same number of protons). Thus, the density and possibly other physical properties will differ slightly and maybe enough to affect transport through the plant.

Yes it does. If I get out of the sun as soon as my skin gets a little red, I have no sunburn by the next day. It's the best way to do it, either that or wait for a little redness then put on high factor sunblock for the rest of the day to give your skin a rest. Maximum tan, maximum getting your skin used to the sun.

No it doesn't, as I discovered in Greece one summer. Shirt off for 15 mins, shirt back on, no change to skin colour until later in the evening when sun-burn started.

Then you must have weird skin. Everyone I know goes red well before they've had too much. Some quickly, some not, but there's always a warning.

In fact if you managed to get burnt in 15 minutes, you have some seriously f***ed up skin. Doesn't it ever see the sun?

You need to watch the area affected for skin cancer.

Or just stop being an alarmist.

Interesting, thanks.

That's what I expected...

but that makes sense too; Huge's link specifically mentions water with different hydrogen isotopes.