Impact on blood Pb levels of maternal and early infant feeding practices of First Nation Cree in the Mushkegowuk Territory of northern Ontario, Canada

Abstract

Exposure to Pb in-utero and in infancy has been associated with cognitive risk, even at low blood Pb levels of 0.48–0.96 µmol L⁻¹. Based on the hypothesis that wild game consumed by First Nation women of Mushkegowuk Territory contains Pb that might be transferred through blood or breast-milk to the fetus or infant, the study's objectives were to describe: (1) Pb in maternal and cord blood at birth and infant blood at 4 months, and (2) dietary influence on Pb status. Cord and maternal Pb were 0.10 ± 0.08 and 0.11 ± 0.06 µmol L⁻¹ (x ± SD), respectively, and were significantly correlated (r = 0.77, p < 0.0001, n = 70), as was infant blood Pb (0.08 ± 0.05 µmol L⁻¹) with matched cord blood (r = 0.65, p < 0.0001, n = 30). Two cord blood samples (3%) were above 0.48 µmol L⁻¹. Pb in breast-milk at 0.010 ± 0.008 µmol L⁻¹ (n = 25), was significantly lower than Pb in commercial formula or evaporated milk-based feedings (range 0.02–0.05 µmol L⁻¹, p < 0.05), and correlated with matched maternal blood Pb (r = 0.55, p < 0.005). However, in a sub-sample of infants (n = 31), blood Pb was similar for breastfed and formula-fed groups, though above the evaporated milk-fed group (p < 0.05). Maternal consumption of wild fowl, mammals and fish, estimated from the previous year, provided, respectively, 128 ± 124, 46 ± 68 and 8 ± 13 MJ annum⁻¹. Traditional animal food intake, especially wild fowl, correlated significantly with cord blood Pb (Spearman rank correlation, p = 0.017). Although blood and milk Pb levels were largely within acceptable ranges, the presence of some elevated levels and association between blood Pb and traditional game consumption may reflect the legacy of using lead-containing ammunition.