Analysis of the Body Distribution of AbsorbedDose in the Organs of Three Species of Fish fromSepetiba Bay

摘要

The body distribution of Polonium-210 in three fishes from the Sepetiba Bay(Macrodon ancylodon, Micropogonias furnieri and Mugil curema) has been studied under theapproach of the Department of Energy of the United States of America (DOE) that set the limit ofabsorbed dose rate in biota equal to 3.5 x 10~3μGy/y, and that also established the relation betweendose rate (D) and radionuclide concentration (C) on a fish muscle fresh weight basis, as follows: D= 5.05 E x N x C, assuming that the radionuclide distribution is homogenous among organs. Twohypotheses were tested here, using statistical tools: 1) is the body distribution of absorbed dosehomogenous among organs? and 2) is the body distribution of absorbed dose identical amongstudied fishes? It was concluded, as expected, that the distribution among organs is heterogeneous;but, unexpectedly, that the three fishes display identical body distribution pattern, although theybelong to different trophic levels. Hence, concerning absorbed dose calculation, the statement thatdata distribution is homogenous must be understood merely as an approximation, at least in thecase of Polonium-210.