Overview
This comparative biomonitoring study measured total arsenic levels in multiple biological matrices from pregnant women and neonates in Comarca Lagunera (CL), a region with chronic drinking-water arsenic contamination in northern Mexico, versus a non-exposed comparison population in Saltillo. The authors demonstrated that arsenic crosses the placenta and is excreted in breast milk, establishing both as routes of early-life exposure. High urinary arsenic persisted in neonates four days after birth despite the theoretical elimination half-life, suggesting continued exposure through breast milk.
Key numbers
| Matrix | Population | N | Mean (µg/L or µg/kg) | Range | p-value |
|---|---|---|---|---|---|
| Drinking water | Exposed | — | 47.7 µg/L | 20.6–709.3 µg/L | — |
| Drinking water | Non-exposed | — | 0.05 µg/L | — | — |
| Placenta | Exposed mothers | 83 | 7.80 µg/kg | 0.3–33 µg/kg | <0.05 |
| Placenta | Non-exposed mothers | 13 | 2.17 µg/kg | 0.1–8.8 µg/kg | — |
| Maternal blood | Exposed | 80 | 4.96 µg/L | ND–12.4 µg/L | ns |
| Maternal blood | Non-exposed | 14 | 3.85 µg/L | ND–9.7 µg/L | — |
| Maternal urine | Exposed | 79 | 54.92 µg/L | 4.1–190 µg/L | <0.001 |
| Maternal urine (creatinine-adjusted) | Exposed | 80 | 77.04 µg/g-Cr | 15.3–306.5 µg/g-Cr | <0.001 |
| Maternal urine | Non-exposed | 13 | 4.60 µg/L | 0.8–9.4 µg/L | — |
| Maternal urine (creatinine-adjusted) | Non-exposed | 13 | 6.71 µg/g-Cr | 0.7–18.4 µg/g-Cr | — |
| Maternal breast milk | Exposed | 75 | 4.30 µg/L | ND–24.7 µg/L | <0.05 |
| Maternal breast milk | Non-exposed | 13 | 0.87 µg/L | ND–7.4 µg/L | — |
| Neonatal urine (day 3, creatinine-adjusted) | Exposed | — | 107.92 µg/g-Cr | 15.8–671.8 µg/g-Cr | <0.05 |
| Neonatal urine (day 3, creatinine-adjusted) | Non-exposed | — | 14.78 µg/g-Cr | 14.08–33.18 µg/g-Cr | — |
| Neonatal urine (day 4, creatinine-adjusted) | Exposed | — | 17.57 µg/g-Cr | 12.47–22.67 µg/g-Cr | — |
| Neonatal urine (day 4, creatinine-adjusted) | Non-exposed | — | ND | — | — |
Initial study (breast milk only): 33% of exposed maternal samples (25/75) had detectable arsenic (mean 8.5 µg/L, range ND–26.0 µg/L); 13% of non-exposed samples (5/39) detectable (mean 5.3 µg/L, range ND–7.3 µg/L); p = 0.02.
Methods
Total arsenic determined by atomic absorption spectrophotometry with hydride generation (PerkinElmer AnalystTM 200 Waltham MA USA) following wet digestion via modified Cox method. Limit of detection 2.7 µg/L. Recovery rates 90–110%. Quality assurance used US NIST Standard Reference Materials. Urinary creatinine analyzed by Jaffe method.
Implications
This study provides biomonitoring evidence for placental transfer and breast-milk excretion of arsenic in a population chronically exposed through drinking water at 47.7 µg/L (nearly fivefold the WHO standard of 10 µg/L). The persistence of elevated urinary arsenic in neonates 4 days after birth despite theoretical elimination kinetics supports breast milk as a continuing exposure source. The paper notes that, despite high maternal drinking-water exposure, arsenic levels in breast milk were relatively low (approximately 10-fold lower than water levels), attributed to efficient maternal methylation and excretion during lactation. This finding supports a protective effect of exclusive breastfeeding compared to formula reconstituted with arsenic-contaminated water in high-exposure areas. The study identifies a vulnerable exposure window in utero and early postnatal period and notes that neonates in the exposed region may experience more severe health outcomes than reported in lower-exposure US cohorts, underscoring the importance of follow-up for comorbidity associations in later life.
Related evidence
Update history
No substantive edit history is available in this build. The full commit record is available in git.