The paper deals with the experimental findings regarding the effects of non-radiational factors, such as sodium nitrite and nitrate and increased temperature, on the metabolism kinetics of 14C inorganic and organic compounds (14C-sodium bicarbonate, 14C-glucose) in conditions of long-term internal exposure to the nuclide. The authors determined the time which elapses before the steady state is achieved as well as the maximum concentration, the accumulation factor and the dose strength. At a concentration of 3 g/l, nitrites and nitrates were shown to produce no significant modifying effect on the kinetics of 14C metabolism. In hyperthermic conditions, 14C metabolism proved to be more intensive. The findings reported herein may have practical applications in setting up hygienic norms and evaluating the hazards of 14C accumulation in the environment.