Frequently Asked Questions - Daily life

Watches can contain radioactive compounds to make them glow in the dark. 
 
In earlier times, radium containing paint was used. Radium is a natural radioactive compound that emits alpha, beta and gamma radiation. The gamma radiation can penetrate through the watch, causing a (usually small) radiation dose to the person wearing it. 
 
Nowadays, other radioactive substances are used in these glowing paints, like tritium. Tritium only emits low energy beta radiation. This radiation is stopped completely by the window of the watch. It can not even penetrate more than a few millimetres of air. These watches will not give a radiation dose.
 

No, your lunch pack is still safe to eat.
The X-rays will penetrate the bag and everything in it. Part of the radiation will be stopped in by the materials in the bag, that is why you can see the contents. This does not cause the bag to become radioactive, only some radiation went through. Compare it to a window: the sun shines its light through the window all day, but this does not make the window sending out light afterwards.