Scutarasu and Trincă 2023 — Heavy metals in foods and beverages: global review including edible oils
This narrative review in the MDPI journal Foods covers the global situation of heavy metal contamination across major food groups (fruits and vegetables, dairy, meat, edible oils, alcoholic beverages), with a dedicated section (Section 4.4 and Table 4) on edible oils aggregating concentration data from published studies across multiple countries. The review is broad-scope and should be treated as evidence tier B (secondary synthesis, not original data), but its Table 4 provides a useful cross-oil cross-country heavy metal inventory drawing on A-tier primary studies. The review also provides a useful regulatory summary of Codex Alimentarius limits for As, Cd, Pb, and Hg across food matrices.
Key numbers
Edible oil heavy metal concentrations compiled from literature (Table 4; mg/kg unless noted):
Olive oil:
- Cyprus: Cd 0.05 mg/kg (2019, ref 87)
- Turkey: Cd 0.9922 mg/kg (2021, ref 88)
- Iran: Cd 0.0955 mg/kg (2020, ref 89)
- London: Cd 0.143; Pb 0.158 mg/kg (2022, ref 94)
- Pakistan: Cd 4.285; Pb 4.005 mg/kg (2022, ref 95)
- Ukraine: Cd 0.355 mg/kg (2015, ref 96)
- Greece: Cd 0.086 mg/kg (2022, ref 97)
Rice bran oil: Cd and Pb values cross-referenced but specific numbers not tabulated in this section (see Mohajer 2020)
Rapeseed oil:
- Iran: Cd 0.098 mg/kg (2020, ref 89)
- China: Pb 1.96 mg/kg (2016, ref 90)
- Poland: Pb 0.056 mg/kg (2017, ref 91)
- Brazil: Cu 0.81 mg/kg (2015, ref 85)
Sesame oil:
- Iran: Cd 0.0935 mg/kg (2020, ref 89)
- London: Pb 0.158 mg/kg (2022, ref 94)
- Pakistan: Pb 4.005 mg/kg (2022, ref 95)
- Korea: Pb 36.01 µg/kg; tAs 15.18 µg/kg; Al 15.97 mg/kg (2019, ref 41)
Flaxseed oil:
- Korea: Pb 25.65 µg/kg; Cd 70.03 µg/kg; tAs 3.1 µg/kg; Al 29,814 µg/kg = 29.81 mg/kg (2019, ref 41)
Canola oil (Turkey/unspecified):
- tAs 0.062–0.118; Cd 0.097–0.123; Cu 0.027–0.041 mg/kg (2022, ref 92)
Corn oil (Turkey/unspecified):
- tAs 0.095–0.106; Cd 0.018–0.045; Cu 0.027–0.041; Ni 0.024–0.076; Zn 0.613–1.090 mg/kg (2022, ref 92)
Cottonseed oil:
- tAs 0.104–0.116; Cd 0.001–0.008; Cu 0.010–0.062; Ni 0.016–0.078; Pb -0.004–0.016; Zn -0.060–2.148 mg/kg (2022, ref 92)
Soybean oil:
- tAs -0.037–0.125; Cd 0.058–0.129; Cu 0.247–0.283; Ni 0.579–0.677; Pb 0.033–0.070; Zn 0.357–0.588 mg/kg (2022, ref 92)
Sunflower oil:
- tAs -0.019–0.147; Cd 0.024–0.038; Cu -0.026–0.233; Ni 0.153–0.221; Pb 0.022–0.025; Zn 0.411–0.456 mg/kg (2022, ref 92)
- London: Pb 0.274 mg/kg (2022, ref 94)
- Iran: Pb 0.099 mg/kg (2020, ref 89)
- Brazil: Cu 0.81 mg/kg (2015, ref 85)
Regulatory limits summarized (Codex Alimentarius, from text):
- tAs in edible fats and oils: 0.1 mg/kg
- Pb in oils and edible fats: 0.1 mg/kg
- Cd: no Codex limit stated for oils specifically
- Hg: not separately addressed for oils
Methods
Narrative literature review (not systematic, no PRISMA or explicit inclusion criteria). Data in Table 4 is compiled from cited primary studies; the table does not provide the analytical methods used in each primary study. Concentrations reported as published; no conversion or harmonization of units is performed by the reviewers beyond what appears in the original papers. Several negative values appear in Table 4 (e.g., cottonseed Pb -0.004 mg/kg) indicating values below LOQ in the primary source; these should be interpreted as “not detected at LOQ.”
Implications
Certification: The Pakistan and Turkey entries for olive oil Cd (4.285 and 0.9922 mg/kg) are extreme outliers relative to European and Cypriot samples (0.05–0.143 mg/kg). These values, if correct, indicate that geographic origin is the dominant driver of olive oil Cd contamination, not the oil type itself. HMT&C sourcing specifications for olive oil should reference origin region.
Courses: The review’s toxicology section (Section 2) provides well-organized one-page summaries of the health mechanisms of Pb, Cd, As, Hg, Cr, Co, Ni, and Zn that can inform course module intros.
App: Al in flaxseed and sesame oils (Korea study: 15,970 and 29,810 µg/kg respectively) is an unexpected finding worth tracking. These oils are used in specialty health-food contexts. However, treat with caution: negative Pb and As values in some rows of Table 4 indicate methodological issues in at least one of the underlying studies.
Speciation caution: All arsenic values in this review should be treated as total arsenic; speciation into iAs vs. organic forms is not addressed.