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This longitudinal study followed 30 mother-infant pairs in Kashiani, an arsenic-contaminated subdistrict of Bangladesh, to characterize arsenic transfer to breastfeeding infants. Despite high maternal urinary arsenic concentrations (median 134 μg/L at 1 month postpartum), breast milk arsenic concentration remained consistently low (median 0.5 μg/L) across all follow-up timepoints. The authors conclude that breast milk is an inefficient vehicle for arsenic transfer to infants, and arsenic exposure in breastfed infants occurs predominantly through other routes (drinking water, complementary foods, and soil contact rather than through lactation).
Key numbers
| Biomarker | Timepoint | Median | Range |
|---|---|---|---|
| Breast milk arsenic (μg/L) | 1 month | 0.5 | 0.5–1.5 |
| Breast milk arsenic (μg/L) | 6 months | 0.5 | 0.5–2.0 |
| Breast milk arsenic (μg/L) | 9 months | 0.5 | 0.5–1.5 |
| Infant urine arsenic (μg/L) | 1 month | 9.2 | 1.4–61.0 |
| Infant urine arsenic (μg/L) | 6 months | 16.4 | 2.0–98.0 |
| Maternal urine arsenic (μg/L) | 1 month | 134 | 18–632 |
| Maternal urine arsenic (μg/L) | 6 months | 72 | 9–370 |
Arsenic speciation in infant urine at 1 month: dimethyl arsinic acid (DMA) 5.5 μg/L (median), arsenite (AsIII) 1.5 μg/L, arsenate (AsV) 1.0 μg/L, monomethyl arsonic acid (MMA) 0.7 μg/L, arsenobetaine (AsB) 0.2 μg/L.
Methods
Study design: Prospective longitudinal follow-up of mother-infant pairs recruited at delivery and followed at 1, 6, and 9 months postpartum. Location: Kashiani subdistrict, Bangladesh, endemic for high groundwater arsenic. Sample collection: breast milk via manual expression, maternal and infant urine (spot samples). Analytical method: graphite furnace atomic absorption spectrometry (GF-AAS) with limit of detection (LOD) 0.50 μg/L. Arsenic speciation performed using high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Sample size: 30 mother-infant pairs with complete data at all three timepoints.
Implications
Breast milk arsenic concentration is low despite high maternal exposure, indicating that lactation does not concentrate or preferentially transfer inorganic arsenic to infants. The median breast milk concentration of 0.5 μg/L is below WHO provisional permissible limits for drinking water (10 μg/L) even when accounting for the volumes infants consume. High infant urinary arsenic (exceeding maternal concentration) indicates that arsenic exposure in breastfed infants in contaminated areas occurs through routes other than breast milk — likely drinking water, complementary foods initiated before 6 months, and environmental contact. The predominance of DMA in infant urine relative to inorganic arsenic species suggests either preferential renal clearance of metabolites or continued exposure to organically methylated forms.
Wiki pages updated on ingest
metals/arsenic.md— evidence on human milk as low-transfer matrix; arsenic bioaccumulation pathway comparisoningredients/breast-milk.md— contaminant profile update for arsenic in human milk; speciation dataregulations/who-drinking-water-arsenic-guideline.md— contextual reference for breast milk arsenic comparison to 10 μg/L permissible limit
Page history
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