Hernández-Montoya et al. 2026 — Heavy metal contamination in foods: review of detection, regulation, and health risk
This scoping review (PRISMA-ScR framework, 121 studies from 255 initial records) synthesizes peer-reviewed literature on the occurrence of five priority toxic metals (As, Cd, Pb, Hg, Ni) in food matrices, emphasizing contamination pathways, analytical detection strategies, and documented health effects. Key findings include: widespread accumulation in staple foods (cereals, vegetables, seafood, processed products) with concentrations frequently approaching or exceeding international regulatory limits in regions with high anthropogenic pressure; and a growing role for emerging detection technologies (portable XRF, Raman/SERS, electrochemical biosensors, environmental magnetism) as complements to conventional ICP-MS and AAS reference methods. The review provides a useful synthesis of maximum permissible limits from Codex Alimentarius (CXS 193-1995, Rev. 2024), EU Regulation 1881/2006, and EU Regulation 2023/915 across food matrices.
Key numbers
Regulatory limits table (Table 1 in paper — key entries for HMI purposes):
Arsenic:
- Edible fats and oils: 0.10 mg/kg (Codex 193-1995 Rev. 2024)
- Salt/food-grade salt: 0.50 mg/kg (Codex 193-1995 Rev. 2024)
- Natural mineral water: 0.01 mg/L (Codex)
Cadmium:
- Husked rice: 0.35 mg/kg (EU 1881/2006)
- Polished rice: 0.20 mg/kg (EU 1881/2006)
- Rice: 0.40 mg/kg (EU 1881/2006 — note: review lists both; inconsistency may reflect different rice types)
- Leafy vegetables: 0.20 mg/kg (EU 1881/2006)
- Legumes and tubers: 0.10 mg/kg (EU 1881/2006)
- Chocolate >50% cocoa: 0.80 mg/kg (EU 1881/2006)
- Chocolate >70% cocoa: 0.90 mg/kg (EU 1881/2006)
- Grains (wheat, maize, legumes): 0.20 mg/kg (Codex/EU 2023/915)
Lead:
- Seafood (mollusks, bivalves, cephalopods): 2.00 mg/kg (Codex 193-1995 Rev. 2024)
- Food-grade salt: 0.50 mg/kg (Codex 193-1995 Rev. 2024)
- Infant foods: 0.01 mg/kg (Codex/EU 1881/2006)
- Milk and dairy products: 0.02 mg/kg (Codex/EU 1881/2006)
- Fruits and vegetables: 0.10 mg/kg (Codex 193-1995 Rev. 2024)
- Cereals and grains: 0.20 mg/kg (Codex 193-1995 Rev. 2024)
- Meat (beef, pork, poultry): 0.10 mg/kg (Codex 193-1995 Rev. 2024)
- Fish: 0.30 mg/kg (Codex 193-1995 Rev. 2024)
Mercury:
- Fish (general): 0.50 mg/kg (Codex 193-1995 Rev. 2024)
- MeHg in large predatory fish (shark, marlin, tuna): 1.0–1.7 mg/kg (Codex 193-1995 Rev. 2024)
Contamination burden: Approximately 14–17% of agricultural soils globally contain toxic metal concentrations exceeding permissible limits; Cd highest exceedance rate, followed by Ni and Cr. A “metal-enriched corridor” across southern Europe, Middle East, South Asia, and China exposes 0.9–1.4 billion people.
Rice highlighted as repeatedly identified with high capacity to accumulate Pb and Cd, with concentrations exceeding regulatory thresholds in some contexts (variety, irrigation, soil pH, fertilizer use).
Methods (brief)
Scoping review, PRISMA-ScR. Database search: Scopus, Web of Science, ScienceDirect, SpringerLink, Wiley Online Library, Google Scholar. 255 initial records, 60 duplicates removed, 195 screened, 74 excluded, 121 included. No quantitative meta-analysis (methodological heterogeneity prevented it). No formal risk-of-bias assessment. Literature included through 2026. Primary focus: As, Cd, Pb, Hg, Ni; studies on Cr and Sn excluded by design.
Implications
Certification: Useful as a high-level synthesis of regulatory limit landscape across Codex and EU frameworks, updated through 2026 (including Codex Rev. 2024 and EU 2023/915). The regulatory limits table provides a convenient cross-reference, but should be verified against primary regulatory sources before citing specific values. Evidence tier B (review) — do not use as primary evidence for concentration values.
Courses: Provides strong framing for the “why detection matters” and “regulatory complexity” sections of courses. The emerging detection technologies section (XRF, SERS, biosensors, environmental magnetism) is a useful update on the non-reference-lab options.
App: No new commodity-level concentration data. Use as regulatory context source only; the concentration data cited here comes from the 121 primary studies, not from new measurements.