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Metabolic data for polonium
96
REPORT OF COMIMTTEE 2
METABOLIC DATA FOR POLONIUM 1. Metabolism Data from Reference Man (ICRP, 1975). Daily intake of polonium 0.1 Bq No data on the polonium content of the body are given in Reference Man (ICRP, 1975). However, Blanchard (1967) and Holtzman (1963) have reported measurements of the ‘i”Po content of various tissues. Their results indicate that the total 2 “PO content of the body is typically 40 Bq with about 60% of this activity in the mineral bone. This distribution arises because of the production of ‘r ‘PO from “‘Pb in situ and has little bearing on the distribution of inhaled or ingested polonium. 2. Metabolic Model (a) Uptake to blood Fink (1950) has reported an absorption of about 20% following oral administration of polonium chloride to a male patient suffering from chronic myeloid leukaemia; 36% absorption by rats has also been reported (Anthony et al., 1956), but no details of the experiments were given. A value forf, of 0.1 has been assumed in the absence of more experimental data. (b) Inhalation classes The ICRP Task Group on Lung Dynamics (1966) assigned oxides, hydroxides and nitrates of polonium to inhalation class W and all other compounds of the element to inhalation class D. Animal experiments with polonium chloride (Fink, 1950; Smith ef al., 1961) are in agreement with this classification and it has been adopted here.
Inhalation class
f1
ti
0.1 0.1
Y
-
(c) Distribution and retention
Polonium is deposited in the liver, kidneys and spleen and is associated with the blood, probably on the red cells (Smith et al., 1961). Excretion data on humans have been summarized by Jackson and Dolphin (1966). These data indicate that the whole-body biological retention of polonium is well described by a function of the form R(t) = e -0.493r130
This retention function has been assumed to apply to individual tissues. Thus, of polonium entering the transfer compartment, fractions 0.1, 0.1, 0.1 and 0.7 are assumed to go to liver, kidney, spleen and all other tissues respectively. Having entered these tissues the polonium is assumed to be retained there with a biological half-life of 50 days.
97
LIMITS FOR INTAKES OF RADIONUCLIDES BY WORKERS
3. Classification of Isotopes for Bone Dosimetry Polonium is assumed to be uniformly distributed throughout all organs and tissues of the body other than the liver, kidney and spleen. Therefore a classification of isotopes of the element for the purposes of bone dosimetry is not required. References Anthony, D. S., Davis, R. K., Cowden, R. N. and Jolley, W. P. Experimental data useful in establishing maximum permissible single and multiple exposures to polonium. In: Proceedings of the International Confirence on the Peaceful Uses of Atomic Energy. Vol. 13, pp. 215-218. United Nations, New York, 1956. Blanchard, R. L. (1967). Concentrations of 2*oPb and z‘“Po in human soft tissues. He&h Phys. 13, 625-632. Fink, R. M. Biological Studies with Polonium, Radium and Plutonium. McGraw-Hill, London, 1950. Holtzman, R. B. (1963). Measurement of the natural contents of RaD (Pb”O) and RaF (Po’*O) in human bone-estimates of whole-body burdens. Health Phys. 9, 385-400. ZCRP Publication 23. Report of the Task Group on Reference Man. Pergamon Press, Oxford, 1975. JCRP Task Group on Lung Dynamics (1966). Deposition and retention models for internal dosimetry of the human respiratory tract. Health Phys. 12, 173-207. Jackson, S. and Dolphin, G. W. (1966). The estimation of internal radiation dose from metabolic and urinary excretion data in a number of important radionuclides. Health Phys. 12,481-500. Smith, F. A., Morrow. P. E., Gibb, F. R., Della Rosa, R. J., Casarett, L. J., Scott, J. K., Morken, D. A. and Stannard, J. N. (1961). Distribution and excretion studies in dogs exposed to an aerosol containing polonium210. Am. Znd. Hyg. Ass. J.22,201-208. Annual limits on intake, ALI
and derived air concentrations, of polonium
DAC(Bq/m3) (40 h/wk) for isotopes
Inhalation
Radionuclide 20’Po 2osPo 2O’Po 2’OPo
ALI DAC ALI DAC AL1 DAC AL1 DAC
Oral
Class D
Class W
f, = 1 x 10-l
fi = 1 x 10-l
j-1 = 1 x 10-l
9 x 8 x 3 x 1 x -
10’ 10“ 10’ 105
2 1 1 6 9 4 2 1
x x x x x x x x
IO9 106 109 IO’ IO’ 105 IO4 10’
3 1 3 1 1 4 2 1
x x x x x x x x
lo9 106 109 lo6 lo9 10% lo* 10’
REPORT OF COMIMTTEE 2
METABOLIC DATA FOR POLONIUM 1. Metabolism Data from Reference Man (ICRP, 1975). Daily intake of polonium 0.1 Bq No data on the polonium content of the body are given in Reference Man (ICRP, 1975). However, Blanchard (1967) and Holtzman (1963) have reported measurements of the ‘i”Po content of various tissues. Their results indicate that the total 2 “PO content of the body is typically 40 Bq with about 60% of this activity in the mineral bone. This distribution arises because of the production of ‘r ‘PO from “‘Pb in situ and has little bearing on the distribution of inhaled or ingested polonium. 2. Metabolic Model (a) Uptake to blood Fink (1950) has reported an absorption of about 20% following oral administration of polonium chloride to a male patient suffering from chronic myeloid leukaemia; 36% absorption by rats has also been reported (Anthony et al., 1956), but no details of the experiments were given. A value forf, of 0.1 has been assumed in the absence of more experimental data. (b) Inhalation classes The ICRP Task Group on Lung Dynamics (1966) assigned oxides, hydroxides and nitrates of polonium to inhalation class W and all other compounds of the element to inhalation class D. Animal experiments with polonium chloride (Fink, 1950; Smith ef al., 1961) are in agreement with this classification and it has been adopted here.
Inhalation class
f1
ti
0.1 0.1
Y
-
(c) Distribution and retention
Polonium is deposited in the liver, kidneys and spleen and is associated with the blood, probably on the red cells (Smith et al., 1961). Excretion data on humans have been summarized by Jackson and Dolphin (1966). These data indicate that the whole-body biological retention of polonium is well described by a function of the form R(t) = e -0.493r130
This retention function has been assumed to apply to individual tissues. Thus, of polonium entering the transfer compartment, fractions 0.1, 0.1, 0.1 and 0.7 are assumed to go to liver, kidney, spleen and all other tissues respectively. Having entered these tissues the polonium is assumed to be retained there with a biological half-life of 50 days.
97
LIMITS FOR INTAKES OF RADIONUCLIDES BY WORKERS
3. Classification of Isotopes for Bone Dosimetry Polonium is assumed to be uniformly distributed throughout all organs and tissues of the body other than the liver, kidney and spleen. Therefore a classification of isotopes of the element for the purposes of bone dosimetry is not required. References Anthony, D. S., Davis, R. K., Cowden, R. N. and Jolley, W. P. Experimental data useful in establishing maximum permissible single and multiple exposures to polonium. In: Proceedings of the International Confirence on the Peaceful Uses of Atomic Energy. Vol. 13, pp. 215-218. United Nations, New York, 1956. Blanchard, R. L. (1967). Concentrations of 2*oPb and z‘“Po in human soft tissues. He&h Phys. 13, 625-632. Fink, R. M. Biological Studies with Polonium, Radium and Plutonium. McGraw-Hill, London, 1950. Holtzman, R. B. (1963). Measurement of the natural contents of RaD (Pb”O) and RaF (Po’*O) in human bone-estimates of whole-body burdens. Health Phys. 9, 385-400. ZCRP Publication 23. Report of the Task Group on Reference Man. Pergamon Press, Oxford, 1975. JCRP Task Group on Lung Dynamics (1966). Deposition and retention models for internal dosimetry of the human respiratory tract. Health Phys. 12, 173-207. Jackson, S. and Dolphin, G. W. (1966). The estimation of internal radiation dose from metabolic and urinary excretion data in a number of important radionuclides. Health Phys. 12,481-500. Smith, F. A., Morrow. P. E., Gibb, F. R., Della Rosa, R. J., Casarett, L. J., Scott, J. K., Morken, D. A. and Stannard, J. N. (1961). Distribution and excretion studies in dogs exposed to an aerosol containing polonium210. Am. Znd. Hyg. Ass. J.22,201-208. Annual limits on intake, ALI
and derived air concentrations, of polonium
DAC(Bq/m3) (40 h/wk) for isotopes
Inhalation
Radionuclide 20’Po 2osPo 2O’Po 2’OPo
ALI DAC ALI DAC AL1 DAC AL1 DAC
Oral
Class D
Class W
f, = 1 x 10-l
fi = 1 x 10-l
j-1 = 1 x 10-l
9 x 8 x 3 x 1 x -
10’ 10“ 10’ 105
2 1 1 6 9 4 2 1
x x x x x x x x
IO9 106 109 IO’ IO’ 105 IO4 10’
3 1 3 1 1 4 2 1
x x x x x x x x
lo9 106 109 lo6 lo9 10% lo* 10’