Early-Life Cadmium Exposure and Bone-Related Biomarkers: A Longitudinal Study in Children

BACKGROUND: Chronic cadmium exposure has been associated with osteotoxicity in adults, but little is known concerning its effects on early growth, which has been shown to be impaired by cadmium. OBJECTIVES: Our objective was to assess the impact of early-life cadmium exposure on bone-related biomarkers and anthropometry at 9 y of age. METHODS: For 504 children in a mother-child cohort in Bangladesh, cadmium exposure was assessed by concentrations in urine (U-Cd, long-term exposure) and erythrocytes (Ery-Cd, ongoing exposure) at 9 and 4.5 y of age. and in their mothers during pregnancy. Biomarkers of bone remodeling [urinary deoxypyridinoline (DPD), urinary calcium, plasma parathyroid hormone, osteocalcin, vitamin D3, insulin-like growth factor (IGF) 1. IGF binding protein 3, thyroid stimulating hormone] were measured at 9 y of age. RESULTS: In multivariable-adjusted linear models, a doubling of concurrent ti-Cd was associated with a mean increase in osteocalcin of 2.7 ng/mL (95% CI: 0.042, 5.9) and in urinary DPD of 22 nmol/L. (95% CI: 12, 32). In a combined exposure model, a doubling of maternal Ery-Cd was associated with a mean increase in urinary DPD of 15 nmol /L. (95% CI: -0.047, 30). Stratifying the osteocalcin model by gender (P-interaction( )= 0.001), a doubling of concurrent U-Cd was associated with a mean decrease in osteocalcin of -4.3 ng/mL (95% CI: -8.5, -0.080) in boys and a mean increase of 9.4 ng/mL (95% CI: 5.4, 13) in girls. The same pattern was seen with U-Cd at 4.5 y of age (P-interaction( ) = 0.016). Children's U-Cd and Ery-Cd, concurrent and at 4.5 y of age, were inversely associated with vitamin D3. CONCLUSIONS: Childhood cadmium exposure was associated with several bone-related biomarkers and some of the associations differed by gender.