Signes-Pastor et al. 2018 — Infant Arsenic Exposure During Transition to Solid Foods
This 2018 cohort study from the New Hampshire Birth Cohort Study (NHBCS) directly measured the increase in infant arsenic biomarkers when rice cereal was introduced at weaning. HPLC-ICP-MS speciation. The study demonstrates that rice cereal is the primary driver of the post-weaning increase in urinary DMA and iAs.
Key numbers
Urinary arsenic species (µg/L) pre-weaning (4 months) vs post-weaning (6 months), n=15 infants:
| Species | Pre-weaning median | Post-weaning median | Change |
|---|---|---|---|
| iAs (sum AsIII + AsV) | 0.43 | 0.64 | +49% |
| DMA | 1.06 | 6.15 | +480% |
| MMA | 0.14 | 0.77 | +450% |
LOD for speciated arsenic: 0.011 µg/L.
Rice cereal association: Spearman correlation between rice cereal intake and total urinary arsenic species: ρ=0.90, p=0.03. This is the strongest evidence that rice cereal specifically drives post-weaning arsenic exposure.
Formula comparison (literature-sourced in paper): Powdered formula total arsenic up to 12.6 µg/kg; ready-to-feed formula approximately 20-fold higher arsenic than breast milk median (0.31 µg/L).
Methods
HPLC-ICP-MS speciation; first-void morning urine collected at 4 and 6 months. 15 infants from NHBCS. LOD 0.011 µg/L. Food intake assessed by 3-day dietary recall at each visit. Rice cereal consumption specifically tracked.
Implications
Certification: The DMA spike (+480%) at weaning onset with rice cereal documents that rice cereal is the critical exposure route for organic arsenic metabolites in infants. Combined with iAs data from FDA surveys (100 ppb action level), this provides the exposure-route rationale for the FDA CTZ rice cereal standard.
App: Rice cereal introduction is the key dietary transition for As exposure in infants; flag all rice cereal products as high priority for iAs.