Bruno et al. 2024 — Multi-element contamination in mussels and clams from Faro Lake, Sicily
This study measured Na, Ca, Mg, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Pb, Hg, Be, and Co in water, sediments, and two commercially farmed shellfish species from Faro Lake, a coastal lake used for shellfish aquaculture on the northern coast of Messina, Sicily. Analysis by ICP-MS (single quadrupole) with Hg by DMA-80. Cadmium and mercury concentrations were below the EU legal limits in all samples. Pb in M. galloprovincialis was below the LOQ; in T. decussatus concentrations were below the EU Regulation 915/2023 limit. The concentrations of the non-essential elements (As, Cd, Pb, Hg) were below Tolerable Weekly Intake and benchmark dose values in all samples, indicating that these shellfish from Faro Lake do not pose a chemical risk under normal consumption patterns. Highly significant differences (p < 0.001) were found between the two species for most measured elements. Cr was notably elevated: the study reports an RDA contribution of 191% (mussels) and 405% (clams), reflecting high total Cr in these filter-feeding bivalves.
Key numbers
Sample n: 160 total (80 mussels + 80 clams), collected September 2023.
Non-essential element findings (mg/kg wet weight; exact means in published tables):
- As: detected in both species; below TWI at normal consumption
- Cd: below EU max limit (1.0 mg/kg ww for bivalves under EC 2023/915); below TWI
- Pb: below LOQ in mussels; below EU limit (1.5 mg/kg ww) in clams
- Hg (by DMA-80): below EU limit (0.5 mg/kg ww for bivalves); below TWI
Essential elements of note:
- Cr (total): RDA contribution 191% (M. galloprovincialis), 405% (T. decussatus) — high total Cr; study measures total chromium, not speciated Cr-VI
- Fe: RDA contribution 92% (mussels), 169% (clams)
- Na: RDA contribution 36% (mussels), 77% (clams)
LOD/LOQ ranges across elements: 0.001–1.314 mg/kg and 0.003–4.336 mg/kg respectively. Recovery for certified reference material (ERM-CE278k mussel tissue) was within acceptable range.
Note: The study measures total chromium, not hexavalent chromium (Cr-VI). High total Cr values reflect the natural Cr content of these filter-feeding bivalves and should not be conflated with Cr-VI toxicity.
Methods (brief)
Soft tissue (0.5 g) mineralized by closed-vessel microwave (Ethos 1; HNO₃ + H₂O₂) then analyzed by ICP-MS (Thermo Scientific iCAP-Q). Hg by DMA-80 direct mercury analyzer. Samples analyzed in triplicate. ERM-CE278k certified reference material used for accuracy validation. Statistical comparison between species by t-test (SPSS 27). Risk assessment used TWI, TDI, and BMDL₀₁ endpoints per EFSA guidance.
Implications
Certification: Bivalves from this Italian coastal farming site met all EU Regulation 915/2023 limits for Cd, Pb, and Hg. Total Cr is elevated but this reflects the naturally high Cr content of bivalve soft tissue; Cr-VI speciation would be needed to assess toxicological relevance.
Courses: Demonstrates multi-element risk assessment methodology for commercially farmed shellfish; illustrates the distinction between total chromium and Cr-VI in shellfish matrices.
App: Multi-element occurrence data for mussels and clams from Mediterranean aquaculture; confirms below-limit status for Cd/Pb/Hg under EU regulatory framework.