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1.  Concentrations of lead in the tissues of children. 
Twenty-four different tissues from 73 children and infants, including stillbirths, were analysed for lead content. In the youngest group of 49 infants aged under 1 year, including 14 stillbirths, the mean concentrations of lead in their soft tissues were all less than 0.3 ppm and nearly all less than the concentrations found in the soft tissues of older children, or of adults. The mean concentrations of lead in the bones in the infant group were greater than in their soft tissues, but still less than 1 ppm, and were 10-40 times less than in adult bones and about three times less than in the bones of older children. Lower concentrations of lead were observed in the tissues of stillbirths than in those of neonatal live births, at a 95% level of significance by analysis of variance. In 24 children aged 1-16 there was no clear evidence of increase of lead concentrations in the bones with increasing age; neither was there evidence of a difference in the concentrations of lead in types of bone. Although the mean concentrations in the bones were greater in the children aged 1-16 than in those of infants aged under 1 year, the data did not suggest that a progressive accumulation of lead occurred in the bones, probably before the end of the second decade of life, by which time the growing phase will be nearing completion. In 18 children aged 1-9 and in six children aged 11-16 the concentrations of lead in the soft tissues were similar, and comparable with those observed in women. The ratio differences between ash-weight and wet-weight measurement in the different types of bone in children did not differ proportionately from the adult ratios, suggesting a similarity in the patterns of deposition of lead in bone, irrespective of age. No differences in tissue lead concentrations by sex were observed in the infant group of children, or when the concentrations in the tissues were related to the years in which the samples were obtained. Individual tissues showed different concentrations and patterns of distribution of lead, which were skewed more towards low values in the infant group than in older children. The results of other studies, of which there have not been many, were found to be in general agreement with those reported here. The exposure of infants to lead appeared to be less than in older children or in adults, probably for reasons associated with lack of availability and parental care.
PMCID: PMC1008800  PMID: 7193476
2.  A comparison of concentrations of lead in human tissues. 
This postmortem study of lead concentrations in the tissues of 129 subjects is an extension to a report by Barry and Mossman (1970). Lead concentrations in bone greatly exceeded the concentrations in soft tissues and were highest in the dense bones. Bone lead concentrations increased with age in both sexes, more especially in male subjects and in dense bone, varying between mean values of 2-16 ppm in the ribs of children to over 50 ppm in the dense petrous temporal bones of elderly male adults. Male adults contained over 30% more lead in their bones than females. Mean concentrations of lead in the soft tissues varied from less than 0-1 ppm in organs such as muscle and heart to over 2 ppm in the aorta. In most tissues with lead values in excess of 0-2 ppm the male concentrations exceeded female values by about 30%. With the exception of the aorta, spleen, lung, and prostate, lead concentrations did not increase with age in the soft tissues of either sex after about the second decade of life. Children showed concentrations of lead in their soft tissues comparable to female adults, but the concentrations in bone were much lower. It is suggested that children do not possess the same capacity as adults to retain lead in bone. In male adults occupationally exposed to lead the concentrations of lead in bone exceeded the concentrations in unexposed male adults within the same age group by two-to three-fold. Soft tissue lead concentrations between the two groups were less divergent. An assessment of the total body burden of lead revealed higher levels in adult male subjects than in females at mean values of 164-8 mg compared to 103-6 mg, respectively. Over 90% of the total body burden of lead in adults was in bone, of which over 70% was in dense bone. Male adults occupationally exposed to lead had mean total body burdens of 566-4 mg Pb, of which 97% was in bone. The release of lead from bone in conjunction with calcium was not considered to be of physiological significance. Lead concentrations of hair and nails were higher than soft tissue lead concentrations and varied widely. Hair lead measurements were not considered to provide a reliable assessment of lead absorption. The concentrations of lead in tissues of a mixed group of subjects with no known occupational exposure to lead have been shown to be comparable to the findings in earlier studies. Present levels of lead in the environment are not considered to be a hazard to the health of the population in general.
PMCID: PMC1008038  PMID: 1131339

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