Tritium — effects on aquatic living organisms, dose-forming effects

Tritium is one of the most important biologically significant radionuclides. Being a part of the water molecule, ³H is an ideal label for studying the exchange processes between the stratosphere and the troposphere when studying air-mass transport and the water cycle in nature. It is a part of many organic compounds, including biologically important ones. Tritium is a by-product of many radiochemical reactions in the nuclear industry, and its effects on water organisms, particularly low-dose effects, are worthy of special attention. The low-dose effects of tritium on aquatic microbiota have been intensively studied, using luminous marine bacteria as a model microorganism. Low-dose activation has been demonstrated and has been explained by the signalling role of reactive oxygen species, through the "bystander effect" in bacterial suspension. The activation of microbial functions in natural reservoirs by the low content of tritium might result in unpredictable changes in food chains and a misbalance of the natural equilibrium. The transformation of tritium from free tritium water into organically bound compounds occurs mainly in the dark and at a temperature of 25 °C. When tritium enters the fish body with food, up to 56 % of tritium accumulates in the muscle tissue and up to 36 % in the liver. About 50 % of tritium in the liver is bound in non-exchangeable forms. The use of fish fillets containing tritium as food products and the use of drinking water with a tritium content at background levels (2-4 Bq·L^-1) does not significantly contribute to the total dose load on the human body. Acknowledgments: This review was prepared with the partial financial support of the Program of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing (Russian Federation).