Lehel et al. 2024 — Potentially toxic elements in farmed rainbow trout, Italy
Lehel and colleagues measured arsenic, cadmium, mercury, and lead by inductively coupled plasma optical emission spectrometry (ICP-OES) in the flesh of 40 farmed rainbow trout (Oncorhynchus mykiss) purchased at a Hungarian fishery market but originating from an aquaculture farm in Treviso County, Veneto Region, Italy. Mean total arsenic was 1.65 ± 0.49 mg/kg, but the authors note total As cannot be evaluated against a regulatory limit because none exists; estimating inorganic As as 5% of total As gave a mean of 0.08 ± 0.02 mg/kg, with estimated daily intake (EDI) and target hazard quotient (THQ) below reference values. Cadmium exceeded the EU maximum level in 30% of samples, but its EDI and THQ stayed below recommended limits. Mercury was below the limit of detection in all samples. Lead exceeded the EU maximum level in 10% of samples, while its EDI and THQ remained below the reference dose. The hazard index (HI) was below 1 for adults (0.86) but above 1 for children (1.22), so the authors concluded the fish is safe for adult consumption but poses a slight risk to children, particularly during long-term intake.
Key numbers
All concentrations are mg/kg wet weight in fish flesh (muscle) unless noted. Where a metal fell below the limit of detection (LOD), half the LOD value was substituted for statistical evaluation (text §2.2.4). Maximum levels (ML) referenced are EU Commission Regulation 2023/915.
Measured concentrations (Table 3, mg/kg ww):
- Total As: mean 1.65 ± 0.49; min 0.54; max 2.79; 100% above LOD (LOD 0.50); no ML exists
- Inorganic As (estimated as 5% of total As): mean 0.08 ± 0.02; min 0.03; max 0.14
- Cd: mean 0.03 ± 0.02; detectable min 0.05; max 0.07; 30% above LOD and 30% above ML (LOD 0.05; ML 0.05)
- Hg: all <0.50 (below LOD); 0% above LOD; 0% above ML (LOD 0.50; ML applied 0.50)
- Pb: mean 0.16 ± 0.16; detectable min 0.24; max 0.85; 15% above LOD; 10% above ML (LOD 0.20; ML 0.30)
Exceedance detail (text §3.1–3.4):
- Cd: 12 of 40 samples (30%) at or above the 0.05 mg/kg LOD; the same 30% were at or above the 0.05 mg/kg ML; the other 70% were below LOD and entered the calculation at half-ML (0.025)
- Pb: 6 of 40 samples (15%) exceeded the 0.2 mg/kg LOD, highest 0.85 mg/kg; 4 of those 6 (10% of total) exceeded the 0.3 mg/kg ML
- Hg: none of the 40 samples exceeded the 0.50 mg/kg LOD, so all were under the ML
Estimated daily intake (Table 3, µg/kg bw/day):
- Total As: mean 1.55 ± 0.46; min 0.51; max 2.62 (no reference dose exists)
- Inorganic As: mean 0.08 ± 0.02; min 0.03; max 0.13; RfD 0.3; 0% above reference
- Cd: mean 0.03 ± 0.01; min 0.05; max 0.06; RfD 1; 0% above reference
- Hg: <0.47 (below LOD); RfD 0.3; 0% above reference
- Pb: mean 0.15 ± 0.15; min 0.23; max 0.80; RfD 0.16 (adult) / 0.26 (children); 10% above adult reference, 15% above children reference
Target hazard quotient (text §3.1–3.4):
- Inorganic As: 0.26 (mean)
- Cd: 0.03
- Hg: not calculated (all below LOD; deemed not relevant)
- Pb: 0.93 (children), 0.57 (adults)
Hazard index (text §3.5):
- HI = 1.22 (children); HI = 0.86 (adults)
Provisional tolerable intake for Cd (text §3.2):
- PTMI 0.90 ± 0.39 µg/kg bw vs WHO recommended 25 µg/kg bw (≈28× lower)
- PTWI 0.23 ± 0.10 µg/kg bw vs WHO recommended 2.5 µg/kg bw (≈10× lower)
Validation parameters (Table 1, mg/kg):
- As: LOD 0.50, LOQ 1.67, precision 12.7%, trueness 13.6%
- Cd: LOD 0.05, LOQ 0.17, precision 8.4%, trueness −10.9%
- Hg: LOD 0.50, LOQ 1.67, precision 12.3%, trueness 8.1%
- Pb: LOD 0.20, LOQ 0.67, precision 3.5%, trueness −8.4%
QC recovery (Table 2):
- ERM-CE278k mussel tissue: As 102.5%, Cd 106.5%, Pb 91.7%
- ERM-CE464 tuna fish: Hg 98.1%
Exposure parameters: average EU fish consumption 23.97 kg/year → 65.7 g/day/person; average adult body weight 70 kg.
Methods (brief)
Flesh samples (10 g) from 40 rainbow trout (Oncorhynchus mykiss) were ground, homogenized, bagged, and frozen at −70 °C. A 0.5 g aliquot was microwave-digested (CEM MARS 6) in 5 mL nitric acid (69 m/m%) and hydrogen peroxide (30 m/m%), made up to 25 mL with deionized water and analysed after twofold dilution. Arsenic, cadmium, mercury, and lead were determined by inductively coupled plasma optical emission spectrometry (ICP-OES; Perkin Elmer Optima 8300 DV). Yttrium (1 mg/L) and gold (0.25 mg/L, to stabilize mercury) served as internal standards; argon purity 4.6. Certified reference materials mussel tissue ERM-CE278k and tuna fish ERM-CE464 (EC Joint Research Centre, Geel) were used for quality control (the source prints the mussel material as ERM-CE278k in its Methods text but as ERM-CE287k in its Table 2 header; the Methods form is used here). LOD and LOQ were three and ten times the SD of blank samples. Statistical analysis used Microsoft Excel and R 3.3.2; half the LOD was substituted for below-LOD samples. Arsenic was measured as total As — ICP-OES does not speciate — so inorganic As was estimated as 5% of total As rather than measured; mercury was measured as total Hg without methylmercury speciation. Note: the EU maximum level for mercury in Oncorhynchus muscle is 0.3 mg/kg ww (Reg. 2023/915), but the authors compared against 0.50 mg/kg (the fishery-product limit, equal to their Hg LOD); since all samples were below the LOD this does not affect the reported outcome.
Implications
Certification: provides total-As, Cd, total-Hg, and Pb occurrence data (wet weight, muscle) for farmed freshwater rainbow trout from an Italian aquaculture region. Cadmium exceeded the EU maximum level in 30% of samples and lead in 10%, while estimated daily intakes for all four metals stayed below reference doses; relevant occurrence and provenance data for farmed freshwater fish product categories.
Courses: useful for illustrating the distinction between exceeding a per-sample regulatory maximum level and exceeding an exposure-based reference dose, the total-vs-inorganic arsenic estimation problem in fish, and the adult-vs-children hazard-index divergence (HI 0.86 vs 1.22).
App: total-As, Cd, total-Hg, and Pb data for farmed freshwater rainbow trout contribute to species- and product-level contamination profiles; values are wet-weight muscle from a single Italian aquaculture source.
Wiki pages updated on ingest
Verification notes
Fresh-context audit subagent (2026-05-30) verdict PROMOTE; all five checks clean against the source PDF. Two ⚠️/optional items resolved as follows:
- Audit noted the bottom heading is “Wiki pages updated on ingest” rather than the audit-prompt’s expected “Wiki pages this source may touch”; verified — “Wiki pages updated on ingest” is the current template heading (docs/page-templates.md) used across the corpus. False positive; no change.
- Audit noted the source prints its mussel reference material inconsistently (ERM-CE278k in the Methods text, ERM-CE287k in the Table 2 header); verified against PDF p6 vs p7 — correct, this is a typo in the source itself. Added a clarifying parenthetical to the Methods section so future readers do not flag the page’s “278k” as an error. The wiki follows the Methods-prose form.
- Numerical fidelity (Tables 1–3, text §3.1–3.5), speciation (tAs total with iAs estimated at 5%; tHg with no MeHg speciation), Methods, Part 12 brand firewall, and Part 2 wiki/HMTc firewall all confirmed clean.
Page history
The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Description |
|---|---|---|
| ddfd414 | 2026-05-30 | ingest: yildirim2021-humic-fulvic-cd-garden-cress fresh from manual-fetch/seasonal-geographic-variance/auto-fetched |