Environmental metal exposure and growth to 10 years of age in a longitudinal mother–child cohort in rural Bangladesh

Abstract

• Life-long Cd exposure was associated to lower WAZ at 10y, especially in boys. • Maternal Cd exposure was linked to diminished growth during childhood. • Concurrent Pb exposure was associated with lower WAZ and HAZ at 10y in boys. • Effect estimates were small, but of relevance in vulnerable populations. Early-life exposure to arsenic (As), cadmium (Cd), and lead (Pb) has been linked to smaller birth and early childhood anthropometry, but little is known beyond the first years in life. To evaluate the impact of gestational and childhood exposures to As, Cd, and Pb on growth up to 10 years of age. We studied 1530 mother–child dyads from a nested sub-cohort of the MINIMat trial in rural Matlab, Bangladesh. Metal concentrations in maternal erythrocytes during pregnancy and in children’s urine at 10y were measured by inductively coupled plasma mass spectroscopy. Child height and weight were measured at 19 occasions from birth until 10y and converted to height-for-age Z-scores (HAZ) and weight-for-age Z-scores (WAZ). Associations between log 2 -transformed metal concentrations and growth parameters were assessed with multivariable-adjusted regression models. Children’s concurrent urinary Cd (median 0.24 µg/L), reflecting long-term exposure, was inversely associated with WAZ (B: −0.072; 95% confidence interval (CI): −0.12, −0.020; p = 0.007), and possibly HAZ (B: −0.046; 95% CI: −0.096, 0.0014; p = 0.057), at 10y. The association with WAZ was stronger in boys than in girls. Maternal erythrocyte Cd (median 0.90 µg/kg) during pregnancy was inversely associated with WAZ during childhood only in boys (B: −0.071, 95% CI: −0.14, −0.0047, p = 0.036). Concurrent urinary Pb (median 1.6 µg/L) was inversely associated with WAZ (B: −0.084; 95% CI: −0.16, −0.0085; p = 0.029) and HAZ (B: −0.087; 95% CI: −0.15, −0.021; p = 0.010) in boys, but not in girls. Neither gestational nor childhood As exposure (median maternal erythrocyte As 4.3 µg/kg and children’s urinary As 57 µg/L) was associated with growth up to 10y. While all effect estimates were small, environmental exposure to Cd and Pb is common and impaired growth is of public health concern, especially for children already at risk of reduced growth due to malnutrition. Gender differences in susceptibility need further investigation.