Экспериментальное обоснование метода оценки полулетальной дозы облучения для наземного моллюска Fruticicola fruticum M.

Abstract

There are currently no recommendations in international guidelines (in particular, in ICRP publications) regarding the determination of the medial lethal radiation dose for representatives of “non-human biota”. The use of different methods (algorithms) for calculating an indicator with the same input parameters gives results that differ from each other, sometimes by orders of magnitude. Based on this, the purpose of the study is to calculate the median lethal dose of gamma irradiation of the terrestrial mollusk Fruticicola fruticum M. of two age groups using different tools to justify the most adequate method of assessing LD50. Three algorithms were used for the calculation: the computational method of probit analysis, the capabilities of the R computing environment and the ICARDA online calculator. The input parameters for the calculation were the results of an experiment on acute gamma irradiation of a mollusk with doses of 10-300 Gy. The mortality rate of sexually mature mollusks of two age groups after gamma irradiation was quantified. The duration of the experiment was 210 days, the indicator was recorded every 30 days. The highest LD50 values were obtained when evaluating the indicator by the least squares method using the R software environment, the lowest by the probit analysis method. The calculation of LD50/30 is possible only with errors of the order of 100% or more, since the mortality rate reaches 50% 60 days after irradiation. LD50 for terrestrial mollusks decreases every 30 days after irradiation in increments of 1.3-1.7 times (second group) and 1.2-1.4 times (third group). In the time immediately after irradiation of mollusks, all three calculation algorithms used give identical values of the studied indicator, which is why they can be equally used to estimate LD50. The LD50 for longer periods after irradiation differs depending on the calculation method used: about 50 Gy and 25-30 Gy for the second and third age groups, respectively. At the same time, the results of calculating LD50 using the R and ICARDA programs are almost identical and can be recommended for use, unlike the probit analysis, which leads to underestimated values.