DIETARY LEAD INTAKES FOR MOTHER CHILD PAIRS AND RELEVANCE TO PHARMACOKINETIC MODELS/

Blood and environmental samples, including a quarterly G-day duplicate diet, for nine mother/child pairs from Eastern Europe have been monit ored for 12 to > 24 months with high precision stable lead isotope ana lysis to evaluate the changes that occur when the subjects moved from one environment. (Eastern Europe) to another with different stable lea d isotopes (Australia). The children were between 6 and 11 years of ag e and the mothers were between 29 and 37 pars of age. These data were compared with an Australian control mother/child pair, aged 31 and 6 y ears, respectively. A rationale for undertaking this study of mother/c hild pairs was to evaluate if there were differences in the patterns a nd clearance rates of lead from blood in children compared with their mothers. Blood lead concentrations ranged from 2.1 to 3.9 mu g/dl in t he children and between 1.8 and 4.5 mu g/dl in the mothers, but the me an of differences between each mother and her child did not differ sig nificantly from zero, Duplicate diets contained from 2.4 to 31.8 mu g Pb/kg diet; the mean +/- standard deviation was 5.5 +/- 2.1 mu g Pb/kg and total daily dietary intakes ranged from 1.6 to 21.3 mu g/day. Mea n daily dietary intakes relative to body weight showed that the intake fur children was approximately double that for the mothers (0.218 vs, 0.113 mu g Pb/kg body weight/day), The correlations between blood lea d concentration and mean daily dietary intake either relative to body weight or total dietary intake did not reach statistical significance (p>0.05), Estimation of the lead coming from skeletal (endogenous) sou rces relative to the contribution from environmental (exogenous) sourc es ranges from 8 to 70% for the mothers and 12 to 66% for the children . The difference between mothers and children is not statistically sig nificant (p = 0.28). The children do not appear to achieve the Austral ian lead isotopic profile at a faster rate than their mothers, These d ata provide evidence that the absorption or uptake of lead from dietar y sources is similar in adult females and children of the age in this study. In spire of lower bone lead and faster bone remodeling and recy cling in children compared with adult females, we see no differences b etween the mothers and their children in overall contribution of tissu e lead to blood lead, Results from this study suggest that fractional absorption of ingested lead by children 6-11 years of age is comparabl e with absorption patterns observed among adult females in the 29-37-y ear-old age range. Because pharmacokinetic models apply a 40-50% absor ption even for a 7-year-old children, further investigations on fracti onal absorption of ingested lead Ly young children are warranted. Furt her investigations are especially needed in younger children than thos e who were subjects in the current study, particularly children in the 1-3-year-old age range. In addition, the effect of nutritional status and patterns of food intake on children's lead absorption require inv estigation, particularly given the increased prevalence of marginal nu tritional status among low-income populations that are at increased ri sk of elevated elevated blood lead levels.