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Arsenic, Cadmium, and Lead in Soils and Cereal Grains of the Pannonian Plain (Croatia): Soil-to-Grain Transfer and Dietary Exposure Assessment

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Overview

Brkic and colleagues measured arsenic, cadmium, and lead concentrations in soils and three cereal grain types (wheat, barley, maize) collected from four counties in the Pannonian Plain of Croatia during the 2019 and 2020 harvest seasons. The study assessed soil-to-grain transfer factors (TFs) and estimated dietary exposure for both adults and children, applying deterministic and probabilistic Monte Carlo approaches. Metal concentrations in grains were generally low for all three crops. Both deterministic and probabilistic HQ and HI values remained below 1 for adults and children, indicating low non-carcinogenic risk from cereal consumption alone. However, regional variability in TF values was notable, with elevated TFs for arsenic and lead observed in Medimurje County despite relatively low soil concentrations.

Key numbers

  • Sample set: 196 cereal grain samples (57 wheat, 50 barley, 89 maize) collected from four counties (R1 Medimurje, R2 Slavonski Brod-Posavina, R3 Virovitica-Podravina, R4 Osijek-Baranja). 43 paired soil samples collected from the same general regions.
  • Analytical method: ICP-MS (Agilent 7900 system). Microwave acid digestion of 0.5-1.0 g of homogenised sample with 3 mL 67% HNO3 and 1 mL 30% H2O2 (MLS-1200 Mega microwave system, Milestone). Isotopes analysed: 75As, 111Cd, 208Pb, all with Rh-103 as internal standard in KED (kinetic energy discrimination) collision-reaction mode.
  • LOD (mg/kg dry weight): arsenic 0.010, cadmium 0.004, lead 0.002. LOQ (mg/kg dry weight): arsenic 0.025, cadmium 0.010, lead 0.050 (Table 3).
  • Calibration range: 0.2-200 micrograms/L for arsenic and lead; 0.05-50 micrograms/L for cadmium (p. 8 of source).
  • Accuracy verified by certified reference material NIST SRM 1567b (Wheat Flour). Recoveries for arsenic, cadmium, and lead ranged 93-107%. All RSDs below 10%.
  • Grain concentration medians (dry weight, all counties pooled, mg/kg): results reported by county and crop type; exact pooled medians not tabulated in the first five pages read but all counties showed grain metal concentrations generally below EU ML values (Cd 0.10-0.20 mg/kg wet weight, lead (Pb) 0.20 mg/kg wet weight, Regulation (EU) 2023/915) after conversion from dry to wet weight at 14% moisture.
  • Transfer factor (TF) variability: Medimurje County exhibited elevated TFs for arsenic and lead relative to other counties despite low soil concentrations, suggesting enhanced bioavailability. Slavonski Brod-Posavina County showed high soil metal concentrations but low TFs.
  • Probabilistic risk assessment: Monte Carlo simulation applied to account for body weight and cereal intake variability. Ingestion rates modelled using Polish dietary consumption data (vegetables 200.5-292.5 g/day; fruits 135.17-261.83 g/day; cereals 142.57-299.43 g/day) adjusted to Croatian adult dietary patterns.
  • Conservative arsenic exposure assumption: 50% of total arsenic assumed to be inorganic form for assessment purposes.
  • HQ and HI for adults and children below 1 under both deterministic and probabilistic assessment, indicating low non-carcinogenic risk from cereal grain consumption alone under Croatian dietary conditions.
  • Regulatory reference: EU maximum permitted levels from Commission Regulation (EU) 2023/915 (Cd 0.10-0.20 mg/kg wet weight depending on cereal type, Pb 0.20 mg/kg wet weight, table 4). No uniform total arsenic maximum for cereals at time of study; inorganic arsenic regulated for specific products.

Methods (brief)

Cereal samples collected at harvest from agricultural farms in four Pannonian Plain counties. Composite samples per plot formed from 2-kg composites along W-shaped sampling paths in accordance with Commission Regulation (EC) No 333/2007. Samples dried to constant mass, ground and homogenised (Retsch Cyclone Mill, 2 mm sieve). Microwave digestion with 67% HNO3 / 30% H2O2 in an MLS-1200 Mega microwave system (Milestone). ICP-MS analysis on Agilent 7900 in standard and KED collision-reaction cell mode with helium (4.3 mL/min). Internal standard Rh-103 (10 micrograms/L) corrected for instrumental drift and matrix effects. QC applied grain and soil samples equally; procedural blanks run in parallel. Soil samples collected independently from the same counties; soil and grain samples not strictly paired at the individual field level. All grain concentrations expressed in mg/kg dry weight; converted to wet weight at 14% moisture for regulatory comparison.

Implications

  • Certification (HMTc): Cadmium and lead concentrations in Croatian Pannonian Plain cereals were generally below EU MLs, supporting the feasibility of sourcing EU cereals at or near EU regulatory floors. Arsenic speciation data are lacking (50% inorganic assumed), so arsenic exposure estimates carry uncertainty.
  • Courses: Demonstrates that low soil contamination does not necessarily imply low grain metal content (elevated TF in Medimurje), and that integrated soil-plant-grain monitoring is essential for food safety assessment.
  • App: Grain metal concentrations from Croatian Pannonian Plain can be used as European context data for wheat, barley, and maize contamination profiles, with the note that these are regional values from a relatively low-contamination agricultural zone.
  • Microbiome: No microbiome data.

Update history

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