Peculiarities of internal radiation doses due to ¹³⁷Cs and ⁹⁰Sr intake in population from Zhytomyr oblast in a late period after the Chornobyl NPP accident.

Study Objective: To reveal the peculiarities of internal radiation doses in the inhabitants of Zhytomyr oblast and to provide a scientific ground for arrangements on internal irradiation dose reducing in population from contaminated regions in long-term period after the ChNPP accident.

Materials And Methods: Comprehensive radiation monitoring was carried out in 4 settlements in Narodychi region of Zhytomyr oblast. The radiochemical, dosimetric methods (instrumental and numerical) were used in the study.

Results And Conclusions: Significant (2-3.5 times) seasonal increase of incorporated ¹³⁷Cs level was revealed through a WBC-monitoring in residents (both for adults and children) of the supervised settlements of Narodytsky region, Zhytomyr oblast. The exceeding of 1.0 mSv x year⁻¹ dose was revealed in up to 5 % of inspected persons. The maximal registered in those settlements ¹³⁷Cs content of 350 kBq is the source of 10 mSv x year⁻¹ annual dose. ¹³⁷Cs content in milk samples from those settlements didn't change much during a year. Elevation of ¹³⁷Cs content exceeding the permissible level of 100 Bq x litre⁻¹ was found in ~30-50 % of milk samples from Narodychi and Selets villages, whereas in Motiyky and Khrystynivka villages the ¹³⁷Cs content didn't exceed permissible levels. 90Sr content both in potatoes and milk samples was much under the permissible level of 20 Bq x litre⁻¹. ¹³⁷Cs content in potato samples was under the permissible levels. It was found out that main part of internal irradiation doses in the settlements of concern is due to consumption of locally produced victuals i.e. milk and natural/forest-originated products like berries and mushrooms.