Rubio et al. 2023 — Cd, Pb, Hg in cereals from Madeira and Azores
Rubio and colleagues measured cadmium, lead, and total mercury in cereals and cereal derivatives commercially sold in Madeira and the Azores (Portugal’s Atlantic island archipelagos) and assessed dietary exposure against EU regulatory maxima and tolerable intake values. The study found widespread exceedances of EU maximum levels: in Madeira, all cereals except maize exceeded the EU Cd maximum, and 50% of rye and 25% of corn flour samples exceeded the EU Pb limit. Oats showed the highest Cd (0.307 mg/kg) and rye showed the highest Pb (0.347 mg/kg). The results indicate that consumers relying on locally sold cereals in these island territories face meaningful dietary exposures to Cd and Pb, with Margin of Exposure (MOE) values for Pb from rye and corn flour falling below levels generally considered to indicate low concern for toxicity.
Key numbers
Madeira:
- Oats Cd: 0.307 mg/kg (highest; EU maximum for oats = 0.10 mg/kg)
- Rye Cd: 0.237 mg/kg (EU maximum for rye = 0.05 mg/kg)
- Rye Pb: 0.347 mg/kg (EU maximum for cereals = 0.20 mg/kg)
- 50% of rye samples exceeded EU Pb limit; 25% of corn flour samples exceeded EU Pb limit
- All cereals except maize exceeded EU Cd maximum
- Daily consumption of 100 g oats: 93.2–120% of EFSA TWI for Cd (2.5 µg/kg bw/week)
- Daily consumption of 100 g rye flour: similar high Cd contributions
- MOE for Pb from 100 g rye/day: 1,294 (nephrotoxic endpoint), 3,082 (cardiotoxic endpoint) — both below 10,000, indicating potential public health concern
- Rice total Hg: 0.0013 mg/kg; wheat total Hg: 0.001 mg/kg; both below EU limit of 0.01 mg/kg
Azores:
- Corn flour Pb: 0.72 mg/kg (highest; 85.7% of samples exceeded EU limit of 0.20 mg/kg)
- MOE for Pb from 100 g corn flour: 626 (nephrotoxic), 1,490 (cardiotoxic)
- Cd in corn flour: regular consumption makes <10% contribution to Cd TDI (low concern)
Methods (brief)
ICP-MS (inferred from paper context; standard for multi-element food analysis). Sampling from retail markets in Madeira and Azores. Exposure assessment using standard EFSA/EU body weight assumptions for adults. Risk characterization via MOE for Pb and %TWI for Cd. Total mercury only (no methylmercury speciation performed on cereals).
Implications
Certification: High-evidence exceedance data for EU Pb and Cd limits in commercially sold cereals from EU territory. Demonstrates that regulatory limits are exceeded in real market samples, not just contaminated-site studies. Directly relevant to HMT&C cereal-based product certification limits.
Courses: Excellent case study showing how island/import-dependent food systems can produce concentrated contaminant exposure when monitoring is insufficient.
App: Rye, oats, and corn flour from Atlantic island origins are flagged risk ingredients for Cd and Pb. App should note that EU-sold cereals can still exceed regulatory limits.