eli5 How come if highly radioactive radium was on watches that the wearers didn’t succumb to radiation poisoning at the wrist?

Question

eli5 How come if highly radioactive radium was on watches that the wearers didn’t succumb to radiation poisoning at the wrist?

In: 186

Answer 1

A lot of radioactive material doesn’t penetrate very far through through even air let alone metal/glass.

The way you get issues is typically from ingesting/inhaling radioactive material, or worst case scenario the stuff you’re ingesting is not only radioactive but also bioaccumulates (your body mistakes it for something it needs and uses it, making it remain in your body to cause damage for a long period of time).