Concerns of increased risk from tritium intake by humans have been claimed in the past. The arguments concerning the radiobiological effectiveness of tritium, its longer retention in the human body and the presence of tritium in the DNA hydration shell are analysed in this paper. A biokinetic model for tritiated water and organically bound tritium retention in the human body is used, based on a common approach for mammals using energy and hydrogen metabolism and tested separately with animal experiments. Extension to this model to humans considers the increased role of the brain, food quality and unique growth patterns of humans. Various ages and genders for Caucasians are considered. For an intake of tritium in organic forms in the diet, the retention for the female is of about a factor 2 compared with ICRP recommendations. Effective dose coefficients are estimated to be about a factor of 2 to 3 higher than those of the ICRP.