Comparison of observed body retention of uranium in natural condition in an average Indian adult with the values predicted by the ICRP biokinetic model.

The daily intake of natural uranium and its contents in the lungs, skeleton, liver and kidney of an Indian adult population group was estimated using radiochemical neutron activation analysis (RNAA). These data on daily intake (through inhalation and ingestion) were used to compute the uranium contents in the lungs and other systemic organs such as the skeleton, liver and kidney, using the new human respiratory tract model (HRTM) and the new biokinetic model of uranium. The theoretically computed uranium contents in the lungs, skeleton, liver and kidney of an average Indian adult are 1.16, 1.96, 0.07 and 0.04 microg, respectively, and the corresponding experimentally measured values are 1.23 (1.76), 2.92 (2.5), 0.07 (1.76) and 0.19 (1.47) microg in an urban population group living in Mumbai. The values given in parentheses are geometric standard deviation (GSD). It is seen that the measured uranium contents in the lungs, skeleton and liver agree very well with the corresponding computed values, but the measured value for the kidney is observed to be on the higher side of the computed value. However, in view of many uncertainties, the overall agreement between the measured and the computed values can be considered to be good. Therefore, the result from this study can be taken as a validation of the new biokinetic model of uranium in Indian conditions.

Comparison of observed skeleton retention of strontium in average indian adult with the value predicted by the ICRP biokinetic model.

The daily dietary intake of strontium and its content in skeleton, for an Indian adult population group were estimated by experimentally measuring its concentration in total cooked diet and autopsy skeleton samples using radiochemical neutron activation analysis. The data on daily dietary intake of strontium were used to compute its contents in skeleton using ICRP Publication 67 biokinetic model for strontium. The theoretically computed value of strontium (213.8 mg) compared favourably with the measured values (GM 181.2 mg) in an urban population group living in Mumbai representing an average Indian adult (Reference Indian Man).

Distribution of arsenic in human tissues and milk.

Using neutron activation followed by radiochemical separations, the arsenic contents of various human tissues and milk were determined. The reliability of analysis was established by analysing a number of standard reference materials. The concentrations in different human tissues range from 1.6 ng As/g (fresh weight) in kidneys to 2140 ng As/g in hair. The mean arsenic levels are compared with those reported from other countries.

Daily intake of thorium by an Indian urban population.

Thorium intake by an urban group (Bombay) has been estimated using neutron activation followed by simple chemical separation. Daily intake of thorium via all the three sources: food, water and air, is reported in this paper. The major contribution of thorium to intake is through food (2.0 micrograms), followed by water (0.02 microgram) and air (0.02 microgram). The individual food ingredients such as cereals, pulses, vegetables, milk, etc. were also analysed for their thorium content. The cereals were found to contribute most to the daily intake.

Trace element changes in hair during pregnancy: preliminary study.

Using neutrons activation analysis, the changes in concentrations of Cu, Zn and Mn in hair during pregnancy are studied. Scalp and pubic hair samples from both non-pregnant and pregnant female subjects were analysed. The results of this preliminary study are presented. Cu, Zn and Mn levels in scalp hair obtained from pregnant subjects were not significantly different from those of non-pregnant subjects. However, pubic hair samples obtained from subjects in the ninth month of pregnancy showed significantly lower Zn levels whereas Cu and Mn levels remained normal. Studies on two subjects in the last trimester showed a steady fall in Cu and Zn levels in pubic hair with advancement of pregnancy; Mn level did not, however, show any change. The reliability of analysis was checked using standard reference materials, such as Bovine Liver and Orchard Leaves (U.S. NBS).

Concentrations of four essential trace elements in breast milk of mothers from two socio-economic groups: preliminary observations.

Concentrations are reported for Cu, Mn, Mo and Zn in human milk samples obtained from mothers belonging to low and middle per capita family income groups. The trace element levels in milk of both groups are compared for samples obtained at two stages, viz. 3-5 days and 4-6 weeks post partum. Although the Mn level during the first stage appears to be lower in samples from the low income group, the difference is not statistically significantly (p less than or equal to 0.01). However, at 4-6 weeks post partum, Zn is significantly lower (p less than or equal to 0.01) in milk of mothers belonging to this group.

Breast feeding: Mo, As, Mn, Zn and Cu concentrations in milk of economically poor Indian tribal and urban women.

The breast milk of 86 economically poor Indian women was analysed by neutron activation analyses for Mo, As, Mn, Zn, and Cu concentrations. The colostrum of 10 tribal women contained 0.27 microgram Cu/g, 2.1 micrograms Zn/g, 19.9 ng Mn/g, 0.73 ng As/g and 5.4 ng Mo/g, whereas 19 urban women had corresponding concentrations of 0.91 microgram Cu/g, 7.3 micrograms Zn/g, 15.3 ng Mn/g, 0.5 ng As/g and 15.3 ng Mo/g. A survey of mature milk between 1 and 6 months, 6 and 12 months and 1 and 2.5 years indicated decreasing concentrations of Zn and Mo, but increasing Mn concentrations as the post-partum period progressed. Malnourished infants received breast milk containing less Cu, Zn and Mn than those who were better nourished and of the same age group. The results, therefore, imply the necessity of supplementing breast feeds in the economically poorer groups.

Infants with a congenital anomaly and the concentration of Mo, As, Mn, Zn and Cu in the mother's milk.

Thirty-one samples of mothers' milk were analysed by neutron activation analysis for the concentrations of Mo, As, Mn, Zn, Cu 1.5 to 3 months post-partum. Group I consisted of 6 mothers having infants with neonatal obstructive jaundice and exhibited lower mean values of Cu and Mn at 0.18 microgram/g and 11.7 micrograms/g as compared with 16 control subjects with 0.34 microgram/g Cu and 23.0 micrograms/g Mn;Mo levels were approximately twice as high (12.2 micrograms/g) as the control values (6.4 micrograms/g); Zn and As were grossly comparable. Group II consisted of 9 mothers who had delivered infants with either a congenital hydrocephalus (n = 7) or meningomyelocoele (n = 2), exhibited a mean Cu level of 0.27 microgram/g, Zn 1.7 micrograms/g, Mn 25.3 micrograms/g and As 0.45 microgram/g. These findings are discussed in the light of the patho-physiology of the congenital anomaly of the infant.

Studies on the biological half-lives of three important radionuclides released in nuclear power reactor operations.

The four important parameters involved in the calculation of internal radiation dose to the human body, per unit intake of a radionuclide are 1) weight and size of the body organs; 2) the biological (retention) half-life of the radionuclide; 3) radiation weighting factors for the type of radiations emanating from the radionuclide; and 4) the organ weighting factors for the organs being irradiated (target organs). Whereas, for a particular radionuclide, the radiation weighting factor and the organ weighting factors may remain constant for all humans, the other two parameters, namely, the organ weights and biological half-life, are population specific and may differ from one population group to another. For a realistic dose estimation, the population specific data on organ weights and biological half-lives for various radionuclides therefore, are needed.

A sensitive method for the determination of Th in body fluids.

A method involving neutron activation followed by simple radiochemical separation was developed and applied to determine the concentrations of Th in blood serum and urine. The method is sufficiently sensitive to detect 0.025 ng of 232Th. The average concentration of Th found in the blood serum and urine of subjects from normal environments is 7.9 ng L-1 and 2.7 ng L-1, respectively.

Validation of biokinetic models of Cs and I using their daily dietary intakes and organ contents in an adult Indian population.

The daily dietary intakes and total contents of Cs and I in skeletal muscle and thyroid, respectively, for an average Indian adult were estimated by determining their concentrations in the total cooked diet and tissue samples using instrumental neutron activation analysis. These data were then used to predict the biological half-lives of Cs and I and their radioactive counterparts for the Reference Indian Man. The predicted biological half-lives of Cs and I for Reference Indian Man were found to be comparable with the reported values for the ICRP Reference Man.

Comparison of observed lung retention and urinary excretion of thorium workers and members of the public in India with the values predicted by the ICRP biokinetic model.

The daily intake of natural Th and its contents in lungs, skeleton and liver of an Indian adult population group were estimated using radiochemical neutron activation analysis (RNAA) technique. These data on daily intake (through inhalation and ingestion) were used to compute Th contents in lungs and other systemic organs such as skeleton and liver using the new human respiratory tract model (HRTM) and the new biokinetic model of Th. The theoretically computed Th contents in lungs, skeleton and liver of an average Indian adult are 2.56, 4.00 and 0.17 microg, respectively which are comparable with the corresponding experimentally measured values of 4.31, 3.45 and 0.14 microg in an urban population group living in Mumbai. The measured lung contents of Th in a group of five occupational workers were used to compute their total body Th contents and the corresponding daily urinary excretions. The computed total body contents and daily urinary excretions of Th in the five subjects compared favourably with their measured values. These studies, thus, validate the new biokinetic model of Th in natural as well as in occupational exposures in Indian conditions.