Tritium is H3 one of the three isotopes of Hydrogen the others are protium and duterium. only tritium is radioactive.
Tritium is a beta particle emitter. Beta particles are essentially electrons which come from the nucleus of an atom as opposed to the electrons which form the 'shell' of the atom. The isotopes we use in fishing work as the result of the interaction of the beta particles with a phosphor coating on the inside of the encapsulating glass tube. Different phosphors emit different coloured light (photons). It is true that the beta particles produced by tritium cannot pass through the glass capsule. This is because the particles emitted by the tritium as it decays are insufficiently energetic to enable them to penetrate the glass. However and contrary to the learned opinions of some contributors that is not the end of the story. As the beta particles strike the glass they are slowed to a stop. The energy of the particles is absorbed by the molecules of the glass as it slows and it emits another photon. This photon is called Bremsstrahlung radiation. Bremsstrahlung radiation is an x-ray and an x-ray is gamma radiation. The Bremsstrahlung x-rays do penetrate the glass and the acryllic surrounding the glass. They are also easily detectable with an appropriate radiation detector. Not a geiger counter though. A low energy gamma Scintilator is needed. Incidentally the beta particles emitted, should you break the glass tube will pass through clothing and skin quite easily. Though a 3 mm aluminium sheet will stop them.
The recommended cure for the inhalation of tritium is to drink liquids. A six pack of beer or lager should do the job. The amount of tritium in a beta light is unlikely to harm you even if you snorted it all directly, and you would have to be quick to manage even that. Tritium is after all hydrogen and a lot lighter than air. But it is a good excuse (if one is needed) for a few tinnies.
