Overview
Bangladeshi mothers with high arsenic exposure from tube-well drinking water excrete very little arsenic in breast milk (median 1.0 µg/kg, range 0.25–19 µg/kg), predominantly in inorganic trivalent form (arsenite). Despite maternal urinary arsenic concentrations averaging 142 µg/L (range 12–810), exclusively breastfed infants had low arsenic concentrations (median 1.1 µg/L, range 0.3–29), while non-exclusively breastfed infants had much higher concentrations (median 1.9 µg/L, range 0.4–1,520). Infants demonstrated efficient methylation capacity, with 87% dimethylarsinic acid (DMA) in urine versus maternal 77% DMA. This is the first evidence that breastfeeding protects infants from postnatal arsenic exposure even in heavily contaminated areas.
Key numbers
| Measurement | Sample | Median | Range | n |
|---|---|---|---|---|
| Arsenic in breast milk | Maternal | 1.0 µg/kg | 0.25–19 | 79 |
| Arsenic in infant urine (EBF) | 3 months | 1.1 µg/L | 0.3–29 | 59 |
| Arsenic in infant urine (NEBF) | 3 months | 1.9 µg/L | 0.4–1,520 | 39 |
| Maternal urinary arsenic (GW 30) | Pregnancy | 67 µg/L | 10–1,130 | 91 |
| Maternal urinary arsenic (GW 8) | Early pregnancy | 49 µg/L | 12–810 | 97 |
| Maternal blood arsenic | 6 months postpartum | 5.7 µg/kg | 1.8–41 | 38 |
| Infant urine DMA (median %) | 3 months | 87% | 15–100 | 98 |
| Maternal urine DMA (median %) | GW 8 | 77% | 56–97 | 97 |
| Breast milk arsenic species | All form | As(III) predominant | — | 79 |
WHO drinking-water guideline: 10 µg/L. Infants exclusively breastfed received ~1% of maternal urinary arsenic concentration via milk despite 90–1,100 µg/L arsenic in drinking water.
Methods
High-performance liquid chromatography coupled to hydride generation and inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS) for arsenic speciation. Total arsenic in breast milk, blood, and saliva measured by ICPMS following acid digestion. Maternal urine measured by hydride generation atomic absorption spectroscopy (HG-AAS) with subsequent speciation by HPLC-HG-ICPMS. Specific gravity adjustment (SG) applied to urine: infant 1.003 g/mL, maternal 1.012 g/mL. Arsenite [As(III)], arsenate [As(V)], methylarsonic acid (MA), and dimethylarsinic acid (DMA) quantified by HPLC-HG-ICPMS. Detection limits: <0.01 µg/L for blood and saliva; 0.1–0.2 µg/L for urine and breast milk metabolites.
Implications
This is the first quantitative evidence that inorganic arsenic is poorly transferred into breast milk despite high maternal exposure, protecting exclusively breastfed infants during a critical developmental window. Infants demonstrated early capacity for efficient arsenic methylation (87% DMA), linked to maternal choline status during lactation. Findings support continued breastfeeding recommendations in arsenic-contaminated areas. Course modules on postnatal exposure reduction in contaminated regions should cite this protective mechanism. Future research gap: arsenic concentrations in infant formula and weaning foods in endemic areas are unknown and should be prioritized given the contrast with breast milk safety.
Wiki pages updated on ingest
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.