It's a novelty item, the point is it makes it easy to find in the dark:

http://unitednuclear.com/index.php?main_page=product_info...

Seems benign to me, since beta radiation won't penetrate the glass.

See also http://en.wikipedia.org/wiki/Tritium_illumination

Oh! There we go, of course- it's encased in glass. I forgot about that when I was thinking about skin vs beta. Thank you for clearing that up.

From memory Tritium or H-3 is relatively safe unless ingested and is not classed as a radiation risk. [0]

[0] "Nuclide Safety Data Sheet Hydrogen-3" Beta radiation won't penetrate dead skin and has approximately 6mm penetration capacity. http://hpschapters.org/northcarolina/NSDS/3HPDF.pdf

The problem is that Tritium is a lightweight gas which makes it very easy to ingest by inhalation.