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Blood lead concentrations and iron deficiency in Canadian aboriginal infants

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Abstract

Aboriginal Cree infants living in northern Quebec who were 9 months of age were screened for anemia, iron deficiency and elevated blood lead concentrations. Of the 314 infants who were eligible to participate, 274 (87.3%) were screened for anemia, 186 had blood lead concentration measured and 141 of the latter group had iron status determined. The median blood lead concentration was 0.08 μmol/l (range 0.01–1.00 μmol/l). The 25, 50 and 75 percentiles for blood lead concentration were 0.05, 0.08 and 0.12 μmol/l, respectively. The prevalence of elevated blood lead concentrations (>0.48 μmol/l) was 2.7% (95% CI 0.36–5.0). Among infants who had blood lead measured, the prevalence of anemia (hemoglobin <110 g/l) was 25.0% and 7.9% of infants had iron-deficiency anemia (hemoglobin <110 g/l and serum ferritin <10 μg/l). Anemic infants had a higher mean geometric blood lead concentration than did babies without anemia (0.11 μmol/l vs. 0.07 μmol/l, P=0.003). Likewise, infants with iron-deficiency anemia had a significantly higher mean geometric blood lead concentration than infants without iron deficiency anemia (0.16 μmol/l vs. 0.07 μmol/l, P=0.001). There was a significant negative correlation between blood lead and hemoglobin concentrations (r=−0.203, P=0.006) and between blood lead and serum ferritin concentrations (r=−0.245, P=0.003). Infants who were fed traditional food (fish, fowl and game) did not have a significantly different mean geometric blood lead concentration, hemoglobin concentration or serum ferritin concentration than infants who did not eat traditional food. Few infants (5.3%) ate traditional food daily.

Introduction

In urban Canada, most children have low concentrations of blood lead as a result of minimal lead exposure (Levallois et al., 1991; Jin et al., 1995). Aboriginal children living in remote communities have multiple sources of potential lead contact: lead shot used to hunt small game, lead fishing sinkers and wild fowl and game contaminated by lead (Carey, 1977, Tsuji and Nieboer, 1997, Hanning et al., 1997, Belinsky et al., 1996, Dewailly, 1999, Belinsky and Kuhnlein, 2000). There is a well-described biological relationship between iron deficiency and enhanced gastrointestinal lead absorption in animals (Barton et al., 1978, Morrison and Quarterman, 1987), which suggests that iron deficient children are more vulnerable to lead uptake. Iron deficiency is common in Canadian children of aboriginal ethnicity (Moffatt, 1995, Willows et al., 2000a) and these children would be anticipated to be at risk for elevated blood lead concentrations.

High blood lead concentrations are known in Cree adults living in at least one community in northern Quebec. Radiographs of the abdomen of Cree adults sometimes show radioopaque material, assumed to be lead shot. The prevalence of anemia is high in Cree babies in the region (Willows et al., 2000b). In a recent study of anemia in these infants, blood lead concentrations were measured. In this paper, the association between blood lead concentration and anemia and iron-deficiency is reported, as well as the association between traditional food intake and blood lead concentration.

Section snippets

Methods

The James Bay Cree of northern Quebec live in nine communities in the boreal forest region between the 49th and 55th parallels. Traditionally, the James Bay Cree were hunter–gatherers with the diet consisting predominantly of game, fowl and fish (Berkes and Farkas, 1978). Among contemporary Cree, trapping, the goose hunt, fishing and game hunting occur at specific times throughout the year. Despite the incorporation of market food into the diet, traditional food makes an important contribution

Results

Blood was drawn from 274 (87.3%) of the 314 infants who reached 9-months of age during the study period. Maternal age at time of birth and infant birth weight did not differ significantly between infants who were and were not tested. All 274 infants had hemoglobin concentration measured, however, due to reasons of unsuccessful venipuncture or clots forming in blood samples, blood lead concentration could only be measured in 186 infants. As a result of hemolysis of some samples, it was only

Discussion

The majority of Cree infants in this study had blood lead concentrations below the blood lead threshold of health concern (>0.48 μmol/l) for children established by the Centers for Disease Control (1991). In general, blood lead concentrations were low and comparable to aboriginal children in northern Ontario (Smith and Rea, 1995) and non-aboriginal children in Vancouver (Jin et al., 1995) and in southern Quebec (Levallois et al., 1991). Some Cree infants had elevated blood lead concentrations

Conclusion

Based on the results of this study, efforts to minimize contact between Canadian aboriginal infants and environmental lead sources are required. The identification of community lead sources must be addressed in future research. From a broad perspective, vigorous public health policies to improve iron nutrition in aboriginal babies are needed considering the potential for higher blood lead levels in infants with iron-deficiency anemia.

Acknowledgments

Funding was obtained from the Medical Research Council of Canada, the Quebec Public Health Research Grants Program, the Northern Scientific Training Program of the Department of Indian Affairs and Northern Development and the Canada Prenatal Nutrition Program of Health Canada. The Cree Board of Health and Social Services of James Bay supported the study. Community health representatives and health care personnel in James Bay and in hospitals in Chisasibi, Chibougamau and Montreal Children's

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