Study of 239Pu Microdistribution in Liver of Mayak Workers Using Neutron-Activated Measurement Method

Purpose: Conducted research was aimed at studying of microdistribution of 239Pu particles in liver tissues of former MAYAK PA workers. Current research is a continuation of studies of microdistribution of 239Pu particles in lung tissues of former MAYAK PA workers that were conducted earlier and published. Material and methods: Neutron-induced track method was utilized for studying the distribution of sizes of 239Pu nanoparticles. At Southern Urals Biophysics Institute this method was improved, optimized and adapted for studying of plutonium microdistribution in biological tissues. Liver samples studying started in 2020. Samples were chosen from Radiobiology Human Tissue Repository SUBI. Liver samples from Voronezh regional pathology and anatomical bureau and Tobolsk regional hospital #3 were obtained within the search of contemporary liver tissues. Application of liver samples on track detectors and their assembling into plastic box for following irradiation in nuclear reactor at Joint stock company “Institute of Nuclear Materials” was provided similarly to lung samples. Standart pathohistological techniqes were applied. The thickness of liver slides was 5 micrometers. Basic track count was conducted on the results of 36-minute etching. Single tracks and stars were counted. Stars with high density of tracks that exceeded counting abilities were counted on the results of 9-minute etching either directly (if all tracks were distinct) or in accordance with patent for invention RU 2733491 C2 that enables to calculate the number of tracks in a star by distinct peripheral tracks. Results: This study quantitatively compares 239Pu microdistribution in liver of three deceased former Mayak PA workers who were exposed to 239Pu by inhalation and three deceased subjects who had been never employed at Mayak PA (from Ozyorsk, Voronezh, Tobolsk). The comparison is made utilizing neutron-activation method of measurement. The results are compared to the results of less-sensitive autoradiographic method. The study demonstrated that the most of 239Pu activity in liver is concentrated in liver lobules. 239PuO2 nanoparticles found didn’t exceed the size of 20 nm. Track density for three liver samples of subjects who had been never employed at Mayak PA differed for less than two times.