The human body contains small amounts of radioactive substances. The majority of these radioactive substances are of natural origin. Since last century, mankind has produced radioactivity artificially, to be used e.g. in research, industry and health care.  Tritium (super-heavy hydrogen) is such a substance, which is also produced naturally. As tritium is bound into water molecules, it is spread to the human body  through the hydrological cycle. The effective dose to humans from natural tritium is only about 0.001% of the natural radiation from space, ground and ourselves. 

The human production of tritium mainly stems from atmospheric testing of nuclear weapons in the 1950ies and 1960ies, but also from nuclear power reactors, research reactors and research laboratories.Tritium is e.g. used as a tracer in research. Tritium is also used as an ingredient in certain luminescent paint, which can be found in some wrist watches and in telescopic sights. Some tritium may escape from these sources and be transferred to humans in very low, but varying, concentrations. 

Tritium will also be produced in the neutron research facility called the European Spallation Source (ESS), which is currently under construction in Lund. To be able to ensure that ESS in the future complies with the strict demands set by the Swedish Radiation Safety Authority (SSM), measurements of tritium and other radioactive substances are performed to map the current radiation environment around ESS. In one study we have assessed the levels of tritium in humans in the Lund area. The results of these measurements will be used in future assessments of the radiological impact of ESS.

The results of the study are published here:

https://www.sciencedirect.com/science/article/pii/S0265931X19306551