Study design
This cross-sectional analysis examined the metal composition of 159 ready-to-eat baby puree samples purchased from the Spanish retail market. Four product types were analyzed: fruit purees (n=38), chicken purees (n=41), fish purees (n=39), and beef purees (n=41).
Samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to quantify concentrations of 30 elements, including essential trace elements, ATSDR priority list toxic metals, and rare earth elements.
Key findings
Essential elements
Iron, zinc, copper, selenium, manganese, and molybdenum were detected in all samples across all product types, with concentrations consistent with nutritional requirements for infant food fortification.
Toxic elements
Toxic elements from the ATSDR priority list were detected in the following concentrations:
Fish purees (highest contamination across study):
- Mercury (Hg): 28.1 ng/g mean
- Arsenic (As): 346.2 ng/g mean
- Lead (Pb), cadmium (Cd), and nickel (Ni) at lower concentrations
Beef, chicken, and fruit purees:
- Metal concentrations lower than fish purees
- Pb, Cd, and Ni detected at trace levels in most samples
- Mercury levels significantly lower than fish (below 5 ng/g mean for non-fish types)
Rare earth elements
Rare earth elements (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium) were detected across all samples at ppb concentrations. Biological significance of rare earth element exposure from infant food remains undetermined.
Notes on data basis
All concentrations originally reported by the source in the native units of the analysis (ng/g, µg/g, or mg/g on wet weight). Conversion to ppb (µg/kg) on wet weight basis applied during evidence synthesis. No dry-weight conversion factors were needed for this product class (ready-to-eat purees are reported as consumed).
Fish category showed markedly higher arsenic and mercury than other product types, consistent with bioaccumulation of methylmercury in aquatic organisms and arsenic speciation in seafood.
Critical assessment
A-tier source with adequate sample size, multi-element ICP-MS analysis, and retail-market origin reflective of actual infant exposure. Data support risk characterization for fish-based infant purees specifically. Geographic scope limited to Spain; extrapolation to other markets requires caution due to regional differences in ingredient sourcing and water quality.
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## 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](https://github.com/paleofoundation/heavymetalindex). When DOI minting comes online (see [[../docs/schemas/index.md|schema docs]]), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
| --- | --- | --- | --- |
| [bc84bfc](https://github.com/paleofoundation/heavymetalindex/commit/bc84bfc) | 2026-08-02 | major | 8 sections added; narrative text revised |
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