Mititelu et al. 2025 — Heavy metal contamination in food: review of sources, speciation, and health outcomes
This 2025 narrative review from Romanian pharmacy and medical researchers synthesizes the contamination pathways, speciation chemistry, toxicokinetics, and health consequences of Pb, Cd, Hg (including MeHg), As (inorganic and organic species), and Sn across the food supply, with particular attention to how chemical species rather than elemental form governs toxicity. The review provides a consolidated reference table of maximum allowable limits from FDA, EFSA, EPA, WHO, and Codex across food categories including cereals and grains, vegetables, fruits, meat, fish, dairy, baby foods, and canned products, and compiles observed contamination levels from published occurrence studies across multiple countries. It advocates for precise species-level terminology throughout, distinguishing for instance between inorganic arsenic (AsIII and AsV) and organoarsenic forms, and between methylmercury and mercuric ions. The review does not generate original concentration data; it synthesizes published values.
Key numbers
Regulatory limits compiled (Table 1, from FDA/EFSA/EPA/WHO):
Lead (Pb):
- Cereals and grains: 0.02 mg/kg (FDA, EFSA)
- Vegetables: 0.10 mg/kg (EFSA)
- Fruits: 0.10 mg/kg (EFSA)
- Meat and offal: 0.10 mg/kg (EFSA)
- Fish and seafood: 0.30 mg/kg (EFSA)
- Milk and dairy products: 0.02 mg/kg (EFSA)
- Baby foods (fruits, vegetables, yogurts, dry cereals): 0.10 mg/kg / proposed 0.01 mg/kg (FDA)
- Bottled/drinking water: 0.005 mg/L (FDA), 0.01 mg/L (EPA)
Cadmium (Cd):
- Cereals and grains: 0.10 mg/kg (EFSA)
- Leafy vegetables: 0.20 mg/kg (EFSA)
- Root and tuber vegetables: 0.10 mg/kg (EFSA)
- Legumes, fish, meat (excl. offal): 0.05 mg/kg (EFSA)
- Drinking water: 0.005 mg/L (FDA), 0.003 mg/L (EPA)
- Typical Cd range in staple crops (cereals, vegetables): 0.01–0.20 mg/kg (cited from literature)
Mercury (Hg):
- Fish and seafood (general): 0.5 mg/kg (EU Regulation)
- Large predatory fish (tuna, shark): 1.0 mg/kg (EU Regulation)
- Drinking water: 0.002 mg/L (FDA), 0.001 mg/L (EPA)
- EFSA TWI for MeHg: 1.3 µg/kg bw/week
- EPA/NAS reference dose: 0.1 µg/kg bw/day; blood Hg threshold: 5.0 µg/L; hair Hg: 1.0 µg/g
Arsenic (As):
- Rice and rice-based products: 0.1 mg/kg (EFSA)
- Rice cereals for infants: 0.1 mg/kg / 100 ppb (FDA)
- Drinking water: 0.01 mg/L (FDA, EPA, WHO)
- Baby rice cereals reported up to 150 ppb tAs in some products (cited from Spectroscopy 2021 ref [26])
Nickel (Ni):
- Cereal-based products: 0.20 mg/kg (EFSA)
- Chocolate and cocoa products: 0.80 mg/kg (EFSA)
- Nuts and seeds: 0.50 mg/kg (EFSA)
Tin (Sn) observed levels in food (Italy, Table 6 in review):
- Cereals and cereal products (pasta, rice, bread, salty snacks): 3.6 µg/kg (3.6 ppb)
- Preserved foods in unlacquered cans (tomatoes): 46–156 mg/kg; (pineapples): 44–136 mg/kg; (fruit cocktail): 88–107 mg/kg
- Preserved foods in lacquered cans (tomatoes): 3.2–8.8 mg/kg; (carrots): 0.08 mg/kg
- Canned vegetables (Malaysia): 96–937 mg/kg
- Aged cheese (Italy): 5.05 µg/kg
- Meat and meat products (Italy): 5.73 µg/kg
- Preserved and tinned fish (Italy): 10.41 µg/kg
US NHANES biomonitoring medians (cited):
- Urinary As (total): 8.4 µg/L
- Blood Cd: 0.3 µg/L
- Blood Hg: 0.86 µg/L
- Blood Pb: 0.85 µg/dL (about 2.5% of US children 1–5 years exceed 5 µg/dL reference value)
Methods (brief)
Systematic narrative review. Sources retrieved from PubMed, Scopus, Web of Science, Google Scholar using keywords including “heavy metals,” “food contamination,” “mercury,” “lead,” “cadmium,” “arsenic,” “tin.” Inclusion criteria: articles addressing contamination sources, pathophysiological mechanisms, and health effects. No meta-analytic pooling; qualitative synthesis. Published April 2025 (received February 2025). The review does not present LODs; all cited concentration values are sourced from the referenced primary studies.
Implications
Certification: Primary value is as a regulatory-limit reference compilation. Table 1 consolidates FDA, EFSA, EPA, WHO, and Codex limits across food matrices in one place. The tin-in-canned-food section (Table 6) provides the most useful Sn contamination data encountered in this category batch. The unlacquered-vs-lacquered can distinction (Sn ranges from 46–156 mg/kg down to 3.2–8.8 mg/kg in tomatoes) is directly relevant to ingredient sourcing decisions.
Courses: Useful as a broad-brush explainer of speciation chemistry (iAs vs tAs, MeHg vs tHg). The cardiovascular/metabolic health effects sections are accessible for brand QA education. The Flint water crisis example and Bangladesh arsenic sections provide strong risk-communication examples.
App: Tin concentration data in cereals (3.6 µg/kg = 3.6 ppb) is the only primary cereal-level number from this source suitable for contamination profile use; it is secondary (cited from Italian total diet study). All other numbers here are regulatory thresholds or review-cited values and should not be used as contamination profile inputs without tracing to the original primary studies.
Microbiome: Not addressed in this review.