Erol and Ürkek 2025 — Heavy metals in traditional Turkish cheeses (Aho, Golot, Telli)
This study measures 18 elements — including the heavy metals Pb, Hg, As, Cd, Ni, Co, Cr, and Al — in 30 samples of three artisanal cheeses from Turkey’s Black Sea region (Trabzon Province): Aho (a pressed cow’s-milk cheese), Golot (a semi-hard cheese from cow or mixed milk), and Telli (a string-type cheese). Analysis was by ICP-MS (Agilent 7700). The key safety finding is that two outlier samples (6.7% of the 30-sample set) exceeded the hazard index (HI) threshold of 1, driven by a single Golot cheese sample with a Pb concentration of 1788.75 µg/kg and a single Telli cheese sample with a Hg concentration of 468.71 µg/kg. The remaining 28 samples showed HI <1, and mean concentrations for most heavy metals were low relative to European regulatory benchmarks for dairy. The paper demonstrates that artisanal production without standardized sanitation controls can produce occasional extreme outlier values for both Pb and Hg, even in a matrix (cheese) where such values are uncommon.
All concentrations are reported per kilogram (µg/kg, wet weight basis implied; the authors do not state dry vs wet weight explicitly, but cheese metal studies conventionally report on a wet-weight (as-sold) basis unless otherwise specified; this is flagged as a limitation in interpretability).
Key numbers
Heavy metal concentrations (µg/kg) by cheese type (n=10 per type), Table 5:
| Metal | Aho mean | Aho max | Golot mean | Golot max | Telli mean | Telli max |
|---|---|---|---|---|---|---|
| Ni | 154.13 | 276.40 | 1502.47 | 3681.67 | 416.06 | 664.88 |
| As (total) | 3.54 | 8.90 | 2.51 | 3.53 | 4.71 | 6.17 |
| Cd | 2.08 | 7.07 | 3.58 | 10.66 | 3.28 | 9.82 |
| Hg (total) | ND | ND | ND | ND | 154.55 | 468.71 |
| Pb | 56.54 | 108.25 | 241.87 | 1788.75 | 48.08 | 108.00 |
| Cr (total) | 67.90 | 300.76 | 78.03 | 341.95 | 85.43 | 274.79 |
| Al (from Table 2, mg/kg) | 16.57 | 34.63 | 10.01 | 34.55 | 2.53 | 0.70* |
*Note: Telli Al max listed as 0.70 mg/kg in Table 2, with mean 2.53 and min 0.93; this appears to be a data entry discrepancy in the source table where max < mean.
Speciation notes: Hg is reported as total mercury (tHg); no methylmercury speciation. As is reported as total arsenic (tAs). Cr is total chromium, not Cr-VI. Al concentrations are reported in mg/kg (Table 2) while heavy metals are reported in µg/kg (Table 5); the unit shift is as published.
Analytical parameters (Table 1): ICP-MS (Agilent 7700). LOD (µg/L): Hg 0.033, Pb 0.063, Cd 0.037, As 0.489, Ni 0.058, Cr 0.074, Al 0.119. LOQ (µg/L): Hg 0.173, Pb 0.210, Cd 0.125, As 1.629, Ni 0.193, Cr 0.246, Al 0.396. R² all >0.999.
Samples with non-detects:
- Hg: Not detected in any Aho or Golot sample; detected in only 4 of 10 Telli samples (the 154.55 µg/kg mean is driven by those 4 samples, with the other 6 at ND).
- As: Not detected in 1/10 Aho, 4/10 Golot, 5/10 Telli.
- Ni: Not detected in some samples across all types (exact counts not reported in text, but min listed as ND in Table 5 for all three types).
- Cd: Not detected in 1/10 Golot and 1/10 Telli.
THQ and HI results (Table 7):
- Mean HI for all three cheese types was well below 1: Aho 0.160, Golot 0.479, Telli 0.321.
- Two outlier samples exceeded HI=1: one Golot sample (HI 2.875, driven by Pb at 1788.75 µg/kg) and one Telli sample (HI 1.317, driven by Hg at 468.71 µg/kg).
- 93.3% of samples showed HI <1.
- Maximum mean THQ values by cheese: Aho 0.087 (Pb), Golot 0.371 (Pb), Telli 0.395 (Hg).
Exposure parameters: Daily cheese consumption 53.7 g/day (derived from 19.6 kg/year per Turkish Ministry of Agriculture data); BW 70 kg.
Methods (brief)
ICP-MS (Agilent 7700). Wet incineration: 2 g cheese + 8 mL 65% HNO₃ + 2 mL 30% H₂O₂; microwave digestion (Start D, Milestone Inc.) at 200°C for 15 min, held 45 min; diluted to 100 mL with ultrapure water. Health risk assessment uses EPA Regional Screening Levels (RSLs) as RfD source. SPSS 21 for statistics; one-way ANOVA with Duncan’s test; significance level p<0.05.
The paper does not explicitly state wet vs dry weight for the cheese metal concentrations; conventional practice in cheese studies is wet weight (as-sold), and this interpretation is consistent with the order-of-magnitude of the reported values relative to published cheese metal data in the references cited.
Key limitations: n=10 per cheese type; single sampling window (April–May 2025, Trabzon); artisanal cheeses with high production variability; two extreme outliers drive the mean values for Golot Pb and Telli Hg; basis (wet/dry) not explicitly stated.
Implications
Certification: The outlier Pb value (1788.75 µg/kg) in a single Golot cheese sample and the outlier Hg value (468.71 µg/kg) in a Telli cheese sample document that artisanal dairy without standardized process controls can produce episodic extreme contamination, even in matrices (cheese) where regulatory exceedances are uncommon. The EU maximum level for Pb in cheese is 200 µg/kg (Regulation EC 1881/2006); the single Golot outlier exceeds this 9-fold. The EU limit for total Hg in food is 500 µg/kg for most products; the Telli outlier (468.71 µg/kg) is just below this limit, but with only 4 of 10 samples above the detection limit, the contamination event is focal rather than systematic.
Courses: Useful example of artisanal production risk and the value of ICP-MS screening in non-standardized dairy supply chains. The Ni data (mean 1502.47 µg/kg in Golot, max 3681.67 µg/kg) are notable; these exceed EU ML for Ni in many food categories and may reflect equipment or feed-source contamination.
App: Supports flagging artisanal cheeses as potentially elevated in Pb and tHg, particularly for products from regions without standardized dairy safety oversight. The majority (93.3%) of samples in this dataset were within safe ranges, but the tail risk from outlier batches is meaningful.