Karatasli 2018 — Radionuclides and heavy metals in Turkish Mediterranean table olives
This study determined concentrations of natural and anthropogenic radionuclides (226Ra, 232Th, 40K, 137Cs) and heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Pb) in 26 table olive samples from the Mediterranean region of Turkey, and assessed associated health risks via estimated annual effective radiation dose and daily intake of heavy metals. The conclusion is that neither radionuclide nor heavy metal levels in these samples pose health hazards: annual effective radiation doses (average 11 µSv/year) were far below the 1,000 mSv safe level, and daily heavy metal intakes were below WHO maximum daily intake recommendations. Notably, cadmium and arsenic — the two analytes most regulated in food safety contexts — were not measured in this study; the heavy metal panel was limited to Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, and Pb.
Key numbers
Heavy metal concentrations in the edible parts (dry weight, µg/g = mg/kg), n = 26 samples (Table 3):
| Metal | Range (µg/g dw) | Average (µg/g dw) |
|---|---|---|
| Cr | 1.64–2.43 | 2.04 ± 0.05 |
| Mn | 9.97–12.19 | 11.08 ± 0.36 |
| Fe | 138.80–194.40 | 166.60 ± 4.08 |
| Co | 0.13–0.26 | 0.20 ± 0.01 |
| Ni | 2.92–17.67 | 10.29 ± 0.26 |
| Cu | 9.84–17.78 | 13.81 ± 0.71 |
| Zn | 12.82–15.86 | 14.34 ± 0.26 |
| Sr | 3.14–5.86 | 4.50 ± 0.30 |
| Pb | 3.88–5.22 | 4.55 ± 0.04 |
Note on units: values are expressed as µg/g dry weight (= mg/kg dw). The edible parts are converted from fresh weight using a dry-to-fresh mass ratio of 0.2 (i.e., approximately 80% moisture in fresh table olives), so values in mg/kg fresh weight would be approximately one-fifth of these dry-weight values. For example, average Pb of 4.55 mg/kg dw corresponds to approximately 0.91 mg/kg fresh weight.
In comparison with other Turkish olive studies: Fe, Zn, Cu, Mn, and Pb concentrations measured here are higher than those reported by Sahan et al. (2007, ICP-MS, Bursa), Nergiz et al. (2008, ICP-AES), and Tuna (2011). The authors note that geographic and cultivar differences, as well as different analytical methods, may account for the variation.
Concentrations in kernels were generally lower for Ni, Cr, Co, Cu, and Zn but higher for Mn, Fe, and Sr relative to the edible parts.
Radionuclides in edible parts: 226Ra average 37.9 ± 4.1 Bq/kg dw (range 7.6–87.8), 232Th average 7.1 ± 0.5 Bq/kg dw (range 2.7–12.0), 40K average 274.6 ± 14.7 Bq/kg dw (range 158.2–488.3), 137Cs average 7.2 ± 0.7 Bq/kg dw (range 2.0–12.6). 137Cs is below the permitted value of 1,000 Bq/kg.
Daily intake estimates (edible parts, based on 11 g/day consumption and 70 kg adult, Table 5): Pb 0.14 µg/kg body weight/day, Ni 0.32 µg/kg bw/day, Cr 0.06 µg/kg bw/day — all below WHO maximum daily intake recommendations.
Methods
Sample collection: 26 olive samples from 26 distinct districts in Adana, Osmaniye, and Hatay provinces (Mediterranean Turkey). Edible parts separated from kernels. Sample preparation for heavy metals: EPA Method 3052 microwave digestion (HNO3 + HF + HCl + H2O2, CEM MARS 5). Heavy metal analysis: ICP-OES (PerkinElmer Optima, Cekmece Nuclear Research and Training Center). Radionuclide analysis: gamma ray spectrometry (Canberra GX3018 coaxial p-type HPGe detector, resolution 1.8 keV at 1332.5 keV for 60Co, 30% relative efficiency). Counting time adjusted per sample for good statistics. Standard calibration sources used for absolute efficiency calibration (Eckert & Ziegler, 1 L Marinelli beaker, 122–1836 keV).
Key limitation: cadmium and arsenic were not measured. The heavy metal panel reflects the study’s focus on general nutritional and radiological safety of table olives rather than food contaminant surveillance. The Fe, Cu, and Mn values are in the range typical of essential mineral surveys rather than contaminant monitoring.
Basis: dry weight throughout. Fresh-weight conversions require the 0.2 dw/fw ratio stated in the paper (80% moisture).
Implications
Certification: No cadmium or arsenic data — the two analytes most relevant to HMT&C standards for table olives. The Pb average of 4.55 mg/kg dw (approximately 0.91 mg/kg fw) is comparable to or higher than values in prior Turkish studies and warrants comparison with EU Regulation 2023/915 limits for table olives (EU limit for Pb in table olives is 0.10 mg/kg fw per Commission Regulation 2023/915). At approximately 0.91 mg/kg fw, the average here would exceed that limit significantly — though the discrepancy may reflect different processing states, geographic provenance, or dry-weight conversion assumptions. Flag for cross-check against EU 2023/915 table-olive Pb limit.
Courses: Good example of a study that provides geographical breadth (26 districts in three provinces) while missing the most toxicologically critical analytes for food safety purposes. Also illustrates radionuclide monitoring as a parallel food safety assessment not typically covered in HMT&C programs.
App: Use Ni (2.92–17.67 mg/kg dw, average 10.29) and Pb (3.88–5.22 mg/kg dw, average 4.55) as contextual dry-weight reference ranges for Turkish Mediterranean table olives, with fresh-weight conversion applied.