Testing countermeasures to reduce ⁹⁰Sr content in fish products

Activity concentrations of ⁹⁰Sr in fish in lakes located within the Chornobyl Exclusion Zone (ChEZ) reach 100 kBq kg^-1, which is several thousand times higher than the permissible level in Ukraine (35 Bq kg^-1). This study was conducted in the natural conditions of the ChEZ to determine the effectiveness of keeping radioactively contaminated fish in "clean" water to reduce the ⁹⁰Sr content of their muscle tissue, as previously shown in short-term laboratory experiments. It was found that transferring tench (Tinca tinca (Linnaeus, 1758)) from Lake Glubokoye one of the most contaminated lakes in the ChEZ, to a cage in the "clean" Lake Starukha for 45 days did not lead to a significant decrease in ⁹⁰Sr content in both bone and muscle tissues. Establishing permissible levels of ⁹⁰Sr concentration only in fish fillet, and not in the whole fish body (with bone tissue), is appropriate for human radiation protection, since the retention factors of ⁹⁰Sr treatment for boiled bone tissue of crucian carp from the Chornobyl exclusion zone are less than 0.01, and up to 97% of strontium is contained in bone tissue.