[en] Estimation of Pu isotopes concentration in critical organs of adult people is based on the following data and admittances: results of radiochemical analysis of isotopes Pu concentration in the skeleton, lungs, liver and lymph nodes - 346 samples; data on the density of Pu contamination in the settlements (data of the Belarus Glavgydromet); the main source of Pu human intake is inhalation at the time when radioactive cloud was moving and secondary instep of dust during spring-summer period 1986 (considered as single-time intake); average values of Pu resorted from lungs to blood is distributed in human bodies as following : liver-33%, skeleton-51%, remainder-6%, while 10% of Pu is extracted (Research Institute of Radiation Medicine, Gomel branch data); average values of Pu resorption from lungs into blood is equal to the rate of nuclides release from fuel particles with the constant of 0.77 years; plutonium is transferred from blood into critical organs within 4-12 hours; the constants of Pu removal from organs are equal to: for liver - 0,0173 1/year; for the skeleton- 0,00693 1/year; initial Pu concentration in lungs was assume to be equal to its concentration in human bodies in 1993-1997 accounting its removal; transfer rates of Pu as a part of practically dissoluble aerosol particles from lungs into gastro-intestinal tract and its removal rates are relatively high and that is why it does not influence Pu accumulation in the critical organs significantly; Pu isotopes absorption from gastro-intestine into blood is absorption small and it does not influence the quantity of Pu concentration in blood. During statistical development of the data we obtained correlation values between density of Pu surface contamination in the settlements and its concentration in human adults. The correlation coefficient is equal to 0.9. Proposed mathematical model enables to estimate the levels of Pu isotopes concentration in human critical organs (adults, who permanently have been residing the areas with different levels of contamination since 1986 year at the any period of time). (authors)