Overview
This study measured Cd, Co, Cu, Hg, Pb, and Zn in the kidney, liver, and muscle (m. semimembranosus) of 40 wild boars hunter-collected in 2009–2010 in the Nitra and Topolcianky region of western Slovakia. Sex was not a significant factor; tissue type was significant for Cd, Cu, Pb, Hg, and Zn (all p < 0.001) but not for Co. Median Cd, Cu, and Hg were highest in kidney and lowest in muscle; Zn was highest in liver; Pb was highest in muscle (interpreted by the authors as a partial signature of ammunition contamination). Compared against the EU Regulation 1881/2006 maximum levels for pig meat and edible offal — the only EU thresholds available for comparison, since no game-specific thresholds exist — none of the 40 animals was fully fit for human consumption: muscle Cd exceedance affected >75% of specimens, kidney Cd exceedance 98%, muscle Pb exceedance 90%. EFSA margin-of-exposure (MOE) and JECFA provisional tolerable weekly intake (PTWI) calculations are reported for Cd and Pb at multiple consumption intensities.
Key numbers
Table 2 — Metal concentrations by tissue (µg/g wet weight; n=40 animals per tissue):
| Tissue | Metal | Median | Min | Max | Q1 | Q3 |
|---|---|---|---|---|---|---|
| Muscle | Cd | 0.155 | 0.043 | 0.373 | 0.089 | 0.220 |
| Muscle | Cu | 1.62 | 0.935 | 2.51 | 1.38 | 1.79 |
| Muscle | Hg | 0.011 | 0.000 | 0.251 | 0.006 | 0.026 |
| Muscle | Pb | 0.441 | 0.039 | 61.3 | 0.274 | 0.645 |
| Muscle | Zn | 12.1 | 8.46 | 23.1 | 10.3 | 16.0 |
| Liver | Cd | 0.474 | 0.190 | 1.92 | 0.365 | 0.635 |
| Liver | Cu | 3.31 | 2.10 | 5.86 | 3.03 | 3.52 |
| Liver | Hg | 0.032 | 0.003 | 0.113 | 0.026 | 0.055 |
| Liver | Pb | 0.188 | 0.040 | 1.29 | 0.116 | 0.305 |
| Liver | Zn | 26.0 | 19.9 | 52.7 | 23.6 | 29.4 |
| Kidney | Cd | 2.73 | 0.36 | 8.82 | 2.14 | 4.06 |
| Kidney | Cu | 3.78 | 2.09 | 7.19 | 3.20 | 4.15 |
| Kidney | Hg | 0.061 | 0.001 | 0.739 | 0.026 | 0.114 |
| Kidney | Pb | 0.345 | 0.049 | 1.10 | 0.169 | 0.526 |
| Kidney | Zn | 19.9 | 15.8 | 31.9 | 18.2 | 23.2 |
| All tissues pooled | Co | 0.438 | 0.131 | 1.14 | 0.330 | 0.558 |
Cobalt concentrations did not differ between tissues (p = 0.272), so the paper presents Co pooled across all 120 tissue samples. Hg liver median is reported as 0.032 µg/g in Table 2 and approximated as 0.031 µg/g in the abstract; the table value is used here.
Muscle Pb maximum of 61.3 µg/g (an extreme outlier roughly 139× the muscle median) is consistent with the authors’ discussion of bullet-fragment contamination near the wound channel (text page 263; bullet fragments may be present in tissue 25–30 cm from the wound).
Ascending order of median concentrations across tissues: Hg < Pb < Co < Cd < Cu < Zn (text, page 259).
Age-related variation (significant only for Co and Cu):
- Co (p = 0.008): 2-year-olds median 0.495 µg/g w.w.; 4-year-olds 0.379; 5-year-olds 0.390 (significant pairwise differences 2-yr vs 4-yr and 2-yr vs 5-yr).
- Cu (p < 0.001): 2-year-olds median 3.50 µg/g w.w.; 4-year-olds 2.74; 5-year-olds 2.95 (additional significant differences for 3-year-olds vs older animals). Authors interpret lowest concentrations in oldest animals as inverse age relationship for these two essential elements.
- Cd, Pb, Zn, Hg: no significant age relationship despite a literature expectation of age-related Cd accumulation; highest Cd values were nonetheless observed in the oldest animals (text, page 262).
Inter-tissue correlations (R Spearman, only |R| > 0.5 reported; Table 3):
- Muscle Cu–Zn: R = 0.618
- Kidney Cd–Pb: R = −0.564
- Kidney Cu–Zn: R = 0.514
- Pb in muscle vs liver: R = 0.448 (the only significant inter-tissue relationship for a given metal across tissue types)
- Cd liver vs kidney: R = 0.110 (the classical Cd liver–kidney correlation was not observed)
- No correlations between metals were observed in liver tissue.
EU Regulation 1881/2006 exceedance proportions (thresholds for pig meat and edible offal applied; no game-specific EU thresholds exist):
| Tissue | Cd threshold (µg/g w.w.) | Cd exceedance | Pb threshold (µg/g w.w.) | Pb exceedance |
|---|---|---|---|---|
| Muscle | 0.05 | >75% (Q1 = 0.089 already exceeds threshold) | 0.10 | 90% of specimens |
| Liver | 0.50 | ~50% (almost half of specimens) | 0.50 | 10% of specimens |
| Kidney | 1.00 | 98% (only 1 of 40 specimens below threshold) | 0.50 | 28% of specimens |
Authors’ overall conclusion: combining Cd and Pb exceedance counts across tissues, the single specimen with safe Cd in kidney tissue exceeded Pb in muscle, so none of the 40 animals was fully fit for human consumption on the joint Cd+Pb criterion (text, page 264).
Table 4 — EFSA (2010) margin-of-exposure (MOE) for muscle Pb at three game-consumption intensities, 70 kg adult; reference intake from BfR (2014):
| Endpoint | Concentration | MOE — normal (2 meals/yr) | MOE — high (10 meals/yr) | MOE — extreme (90 meals/yr) |
|---|---|---|---|---|
| Cardiovascular (SBP) | Muscle Pb Q2 = 0.155 µg/g | 1.2–4.1 | 1.2–3.7 | 0.9–2.1 |
| Cardiovascular (SBP) | Muscle Pb max = 0.373 µg/g | 0.6–1.0 | 0.2 | 0.03 |
| Nephrotoxicity (CKD) | Muscle Pb Q2 = 0.155 µg/g | 0.5–1.7 | 0.5–1.6 | 0.4–0.9 |
| Nephrotoxicity (CKD) | Muscle Pb max = 0.373 µg/g | 0.3–0.4 | 0.1 | 0.01 |
(Reference: EFSA Scientific Opinion on lead in food; MOE ≥ 10 indicates no appreciable risk for SBP/CKD per EFSA. The source labels the “Concentration used” column with values 0.1550 µg/g and 0.3732 µg/g, which match the muscle Cd column of Table 2 rather than the muscle Pb column; the surrounding text frames Table 4 as a Pb MOE calculation. See Verification notes below.)
Table 5 — Cd PTWI exposure simulation (JECFA-derived PTWI 2.5 µg/kg bw/week; 70 kg adult ⇒ 175 µg/week; 200 g portions; four meals per week of wild boar tissue assumed for the “total weekly intake” column; background non-game intake 48–140% PTWI from Nasreddine & Parent-Massin 2002):
| Tissue (concentration µg/g w.w.) | Weight of single portion at 100% PTWI (g) | No. of 200 g portions to PTWI | Contribution of 4 game meals to PTWI (%) | Total weekly intake (% PTWI, incl. background) |
|---|---|---|---|---|
| Muscle (Q2 0.155) | 1,129 | 5.6 | 70.9 | 119–211 |
| Muscle (max 0.373) | 469 | 2.3 | 171 | 219–311 |
| Liver (Q2 0.474) | 369 | 1.8 | 217 | 265–357 |
| Liver (max 1.92) | 91.1 | 0.5 | 878 | 926–1018 |
| Kidney (Q2 2.73) | 64.1 | 0.3 | 1,249 | 1,297–1,389 |
| Kidney (max 8.82) | 19.9 | 0.1 | 4,030 | 4,078–4,170 |
Authors’ summary: only muscle tissue at average (median) Cd concentration is safe under PTWI when added to background dietary Cd; liver and kidney tissue exceed PTWI on a single-meal basis at the median concentration.
Methods (brief)
Sampling: 40 wild boars (20 females, 20 males; four specimens per age group 1, 2, 3, 4, 5 years) collected by hunters in November and December 2009 and 2010 in the Nitra and Topolcianky region of western Slovakia (Fig. 1 shows the sampling area in the south-west of the country, between the Czech Republic, Poland, and Hungary borders). The abstract erroneously states “eastern Slovakia” — the title, Materials and Methods, and Fig. 1 all clearly identify the sampling region as western Slovakia. Samples of kidney, liver, and skeletal muscle (m. semimembranosus) were collected, bagged, and stored at −18 °C.
Digestion: 1–2 g w.w. of each sample weighed (Mettler AE 200, accuracy 0.0001 g) and microwave-mineralised in 65% SupraPUR HNO3 (Merck, Darmstadt) using a Mars X system at 180 °C for 15 min and 70 °C for an additional 20 min. Digests were filtered (Munktell & Filtrak no. 389, Barenstein) and diluted to 50 mL with deionised water (Simplicity 185 Millipore SAS, Molsheim, France).
Instrumentation: Cd and Pb by electrothermal AAS (Varian SpectrAA 240Z); Co, Cu, Zn by flame AAS (Varian SpectrAA 240 FS). Hg by cold-vapour AAS using an AMA-254 mercury analyser (Altec, Prague), measured directly on fresh tissue without prior digestion.
LODs (fresh-sample basis): Cd 0.5 ng/g; Co 0.25 µg/g; Cu 0.1 µg/g; Hg 0.075 ng/g; Pb 0.5 ng/g; Zn 0.03 µg/g (Table 1). All measured values were above LOD.
Quality control: Multi-standard CertiPUR solution (Merck) for calibration and spiking; recoveries 90–110%. Certified reference materials: BCR-185R bovine liver for Cd, Cu, Pb, Zn (n = 11 replicates) and BCR-463 tuna fish for Hg. CRM trueness with RSD: Cd +8.1% (7.7%); Cu −1.6% (4.1%); Hg −4.7% (3.9%); Pb +4.3% (8.1%); Zn −0.2% (6.1%). No appropriate CRM was found for Co.
Statistical analysis: Robust ANOVA on ranks (Quinn & Keough 2002) with age, sex, and tissue type as categorical factors; Spearman correlation. α = 0.050. Software: Excel 2016 for Mac (Microsoft) and Statistica 12 (StatSoft).
Speciation: total mercury (CV-AAS, no separation of organic/inorganic Hg); the page uses tHg rather than MeHg. The paper does not measure arsenic; the metals list omits As entirely. The paper does not measure hexavalent chromium; Cr was not assayed.
Implications
Certification: Game meat is excluded from the EU Regulation 1881/2006 maximum-level table for Cd and Pb (the table covers pig meat and edible offal explicitly), so the authors’ comparison applies a livestock threshold to a game matrix. Under that comparison, 98% of the wild boar kidney tissue sampled in this study exceeds the 1.0 µg/g w.w. Cd threshold for pig kidney; 90% of muscle tissue exceeds the 0.1 µg/g w.w. Pb threshold for pig muscle. The combined Cd-plus-Pb fitness criterion failed for all 40 animals. Any game-meat certification framework will need an explicit threshold for kidney Cd in wild boar (the most concentrated tissue × metal combination in this dataset), an explicit threshold for muscle Pb (where ammunition contamination drives the right tail, with a maximum of 61.3 µg/g w.w. ≈ 139× the muscle Pb median), and a route for handling the substantial fraction of carcasses whose offal exceeds Cd thresholds while muscle does not.
Courses: Useful as a case study in (1) game meat as a contamination matrix distinct from farmed meat — the ammunition pathway for Pb and the bioaccumulation pathway for Cd in kidney produce contamination distributions that livestock-derived limits were not designed for; (2) the use of margin-of-exposure (MOE) methodology for non-threshold toxicants where PTWI is no longer considered protective (Pb); (3) why median values can pass a fitness check while the same dataset’s max values fail it by orders of magnitude — the muscle Pb max of 61.3 µg/g w.w. is the kind of outlier that makes single-point summaries misleading.
App: Provides Slovak wild-boar occurrence data for inclusion in the game-meats product page and the meat-and-poultry / organ-meats ingredient pages. Per-tissue concentration distributions (median, range, Q1, Q3) are reported for Cd, Pb, tHg, Cu, Zn at n = 40, and Co at n = 120 (all tissues pooled). Sampling year range 2009–2010 anchors this dataset on the older end of the wild-boar literature.
Related evidence
- Meat and Poultry
- Organ Meats (Kidney and Liver)
- Game meats (venison, bison, rabbit)
- Cadmium
- Lead
- Mercury
- Copper
- Zinc
- Cobalt
- Commission Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs
- EFSA — Lead in Food (2010), No-Threshold Position
- EFSA — Tolerable Weekly Intake for Cadmium, 2.5 µg/kg b.w./week
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