It is radioactive (an average 6 keV beta emmitter) and has a half-life of 12.3 years. The low-energy beta radiatoin from tritium cannot penetrate human skin, so tritium is only dangerous if consumed in large quantities.
Tritium figures prominately in studies of nuclear reactions, especially nuclear fusion due to its favorable reaction cross-section and high energy yield. Please explain further.
Small amounts are used with phosphors for self-illuminating devices such as watches and exit signs.