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Low inorganic arsenic in hydrolysed-rice formula used for cow's milk protein allergy

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Overview

Meyer and colleagues measured inorganic arsenic (As(V)) and dimethylarsinic acid (DMA) in commercially available hydrolysed-rice infant formula (HRF) powders sourced from Italy, France, and Belgium and analysed at the Institute for Global Food Security, Queen’s University Belfast. HRF is used in the management of cow’s milk protein allergy (CMPA) when breastmilk is not available and conventional extensively hydrolysed casein/whey or amino-acid formulas are not used. Across six distinct product variants (ten batch-level measurements presented), As(V) ranged from 9 to 20 µg/kg in dry powder, with calculated daily As(V) exposure for a typical 0–6 month, 8 kg infant of 0.16–0.23 µg/kg body weight/day — roughly an order of magnitude below the WHO 2 µg/kg b.w./day exposure benchmark and below the EFSA-reported childhood dietary inorganic arsenic (iAs) exposure range (0.24–0.43 µg/kg b.w./day for infants). The authors concluded that As(V) levels in HRF powder were within the safe range as stipulated by EFSA and WHO, while noting that actual exposure can be modified by arsenic in the tap water used to reconstitute the formula.

Key numbers

  • Sampling design: 6 distinct HRF product variants from 3 European countries (1 Italian, 1 Belgium/France, 4 French); each brand analysed in 2 batches (separate batch numbers) with 2 samples per batch from separate tins; samples, blanks, and CRM run in triplicate.
  • Table 1 presents 10 batch-level rows (one variant has only batch 2 reported; one variant has only batch 1 reported).
  • As(V) range across the 10 batch-level measurements: 9–20 µg/kg (dry powder, as-sampled).
  • DMA range across the 10 batch-level measurements: 2–19 µg/kg (dry powder).
  • Sum of species [As(V) + DMA] range: 11–35 µg/kg (dry powder).
  • By format subcategory (dry powder, µg/kg As(V), batch range):
    • Hydrolysed rice suitable from 0–6 months: 9–20 µg/kg (n=2 batches of one variant).
    • Hydrolysed rice suitable from 6–12 months: 12–13 µg/kg (n=2 batches of one variant).
    • Hydrolysed rice suitable from 0–6 months thickened with carob and corn starch: 14 µg/kg (n=1 batch of one variant).
    • Hydrolysed rice suitable from 6–12 months thickened with carob and corn starch: 12 µg/kg (n=1 batch of one variant).
    • Extensively hydrolysed rice from 0–12 months: 11 µg/kg (n=2 batches of one variant, both 11).
    • Hydrolysed rice suitable from 0–12 months: 9–10 µg/kg (n=2 batches of one variant).
  • LOD for all arsenic species by IC-ICP-MS (calculated from DMA calibration): 0.0003 mg/kg (= 0.3 µg/kg).
  • CRM variance: 2.1% for As(V) on NIST1568b rice flour reference material.
  • Calculated daily As(V) intake: 1.3–1.8 µg As(V)/day for a 0–6 month infant consuming 600–800 mL/day reconstituted HRF (90–120 g powder, based on 4.5 g average scoop size).
  • Calculated daily As(V) exposure: 0.16–0.23 µg/kg b.w./day for an 8 kg infant (50th centile weight, z-score 0).
  • WHO exposure benchmark cited: 2 µg/kg b.w./day (calculated exposure is ~10-fold below).
  • EFSA-reported background dietary iAs exposure cited: infants 0.24–0.43 µg/kg b.w./day; toddlers 0.32–0.45 µg/kg b.w./day.
  • EU drinking-water limit cited: 10 µg/L (Council Directive 98/83/EC).
  • EFSA tap-water-derived iAs intake cited: 1.1–2.0 µg/kg b.w./day (note: this is the EFSA-reported reconstitution-water contribution at the time of publication).
  • No EU maximum level set for infant formulas at the time of publication.

Methods (brief)

Approximately 100 mg of each dry formula powder sample was microwave-digested in 10 mL of 1% nitric acid at 95 °C using the method of Meharg et al. (2008). Arsenic speciation and quantification were performed by Ion Chromatography–Inductively Coupled Plasma Mass Spectrometry (ThermoScientific iCap Q ICP-MS coupled to a Thermo IC5000 Ion Chromatograph) with a gradient mobile phase separating all arsenic species. Quality control used NIST1568b rice flour certified reference material in each analytical batch (variance 2.1% for As(V)). Samples, blanks, and CRMs were tested in triplicate. LOD calculated from the DMA calibration was 0.0003 mg/kg for all species. Dry powder was analysed (rather than reconstituted formula) to remove the confounding effect of arsenic in household reconstitution water. Authors note as a limitation that HRF samples were not compared in this study to extensively hydrolysed casein/whey or amino-acid formulas, which are the conventional CMPA management alternatives.

Implications

  • Certification (HMTc): Contributes dry-powder As(V) and DMA occurrence data for the hydrolysed-rice subset of dairy-free, non-soy infant formula powder for the European market. Sample size is small (6 product variants, 10 batch-level measurements) but speciation is rigorous and the matrix is dry powder native basis, which is directly comparable to other infant formula powder occurrence data. Useful as one of multiple inputs to dry-powder occurrence pooling for the infant formula powder rows.
  • Courses: Illustrates that not all rice-derived infant formula products carry the iAs burden seen in some rice-based cereals; speciation by IC-ICP-MS is the discriminating measurement. Useful case study for brand QA and supply-chain audiences on the importance of speciated arsenic testing rather than relying on total arsenic alone.
  • App: Adds a low-end As(V) occurrence anchor for the hydrolysed-rice-formula subtype of dairy-free, non-soy infant formula powder in the European market.

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