Linear threshold effects of g-irradiation of the terrestrial mollusk F. fruticum M. of the third age group

The ecocentric strategy of radiation protection involves the expansion of experimental bases of radiation-induced effects in representatives of biota. In this article we studied the change in the relevant indicator (mortality) of the terrestrial mollusk F. fruticum M. after g-irradiation with doses from 10 to 300 Gy. The terrestrial mollusk is not yet included in the list of reference species, but it meets the requirements of the ICRP for reference organisms. The aim of the work is to establish dose-effect relationships in the study of mortality of the terrestrial mollusk F. fruticum M. The third age group after acute g-irradiation is used to expand databases on radio-induced effects of biota. The results of a study for mollusks of only the third age group are presented. This research is part of an experiment to identify age-related features of radiosensitivity of a representative of terrestrial malacofauna. The age of the mollusks was determined by the number of revolutions of the shell. The conditions for keeping animals in laboratory were selected in such a way that mortality in the control group remained at zero during the entire experiment. The duration of the experiment is 210 days. The LD50/60 index for the mollusk was estimated by the calculated probit analysis method using the least squares method. The LD50/60 is 141.4±26.3 Gy. The change in the indicator was estimated every 30 days after irradiation. A linear threshold dependence was established for each time range, starting from 60 days after irradiation. It contains two threshold transitions to a new level of mortality and, accordingly, three dose ranges: a dose-independent range at low doses of radiation, a dose-dependent range with an increase in the dose of radiation and a dose-independent plateau when switching to the level of absolute lethality. Four dose ranges of mortality of terrestrial mollusks were established for 210 days after irradiation: 10-130 Gy (100% survival rate), 140-160 Gy (absolute mortality after 180 days), 170-190 Gy (absolute mortality after 150 days), 200-300 Gy (100% mortality after 90 days). At the same time, the greatest dynamics of the increase in mortality is observed in the first 60 days after irradiation.