[ISL]

Radium is also present in Brazil Nuts. Some plants aggregate chemical elements more than others.

We use them to linearize the energy scale in lower-background germanium detectors. Grocery-store potassium chloride sets our energy calibration.

The bad thing about radium in tobacco, I am told, is that the alpha-emitting radium (or the daughters) tends to aggregate in the lungs. Alphas do a lot of nearby damage, hence a mechanism for lung cancer.

I still eat Brazil nuts without a second thought, even though I've measured the gammas...

[battery_cowboy]

Alpha is the worst internally (than gamma or beta) because it's a big particle (2 protons, 2 neutrons) and does lots of damage internally but can't pass through skin or clothes, so externally it's less dangerous. Additionally, the alpha particle can cause minerals in the body to become radioactive, thus extending the danger.

[raverbashing]

> Grocery-store potassium chloride sets our energy calibration.

I'm guessing this gives a new meaning for the phrase "banana for scale"

[ISL]

Could be, though the KCl is a better standard. We know how much KCl we have, and the natural abundance of K40 is well-known.

You'd need a dedicated campaign to assess the potassium abundance in the "standard" banana before you could use it at better than ~100+% errorbars.

The salt-substitute shaker is probably a <5% standard, and we've been using the same one for years.... :).

[saagarjha]

Brazil nuts are known for being particularly high in selenium.