“…as an isotope of hydrogen (the cell’s most ubiquitous element), tritium can be incorporated into essentially all portions of the living machinery; and it is not innocuous." R. Lowry Dobson MD, PhD quoted from The toxicity of tritium 1979.
Beyond Nuclear presents a new fact sheet on tritium discussing where it comes from, how it acts in the environment and humans and what the health hazards of exposure are. References are included.