Armand et al. 2026 — Heavy metals in lettuce and cabbage from Behbahan, Iran
This study measured lead (Pb), chromium (Cr), cadmium (Cd), and nickel (Ni) in lettuce and cabbage purchased from retail outlets in Behbahan, a city in Khuzestan Province, southern Iran, an area characterized by oil and petrochemical industrial development. Mean wet-weight concentrations in cabbage were Pb 0.312, Cr 0.699, Cd 0.0756, and Ni 0.633 mg/kg; concentrations in lettuce were Pb 0.134, Cr 0.306, Cd 0.0601, and Ni 0.320 mg/kg. Cabbage concentrations of Pb and Cr exceeded the health guideline values (0.3 and 0.5 mg/kg, respectively), while all metals in lettuce fell below guidelines. Monte Carlo simulation showed that non-carcinogenic risk (hazard index) was below 1 for both vegetables, but excess lifetime carcinogenic risk (ELCR) was 4.14 × 10^-3 for lettuce and 1.40 × 10^-3 for cabbage, both exceeding the 10^-4 threshold of unacceptable carcinogenic risk.
Key numbers
- Sample: 20 samples each of lettuce and cabbage from 10 retail stores in Behbahan (2 sampling rounds 4 weeks apart); n = 40 total
- Method: ICP after HNO3 digestion at 80°C; reported as wet weight (moisture-corrected from dry-weight measurements at 105°C for 24 h)
- Mean concentrations — cabbage (mg/kg wet weight): Pb 0.312, Cr 0.699, Cd 0.0756, Ni 0.633
- Mean concentrations — lettuce (mg/kg wet weight): Pb 0.134, Cr 0.306, Cd 0.0601, Ni 0.320
- Concentration order in both vegetables: Cr > Ni > Pb > Cd
- Hazard Index (non-carcinogenic): cabbage 1.52 × 10^-1, lettuce 4.58 × 10^-1 (both < 1, no significant non-carcinogenic risk)
- ELCR (total of all four metals): cabbage 1.40 × 10^-3, lettuce 4.14 × 10^-3 (both > 10^-4; unacceptable carcinogenic risk per US EPA criteria)
- Margin of Exposure (MOE) for Pb cardiovascular effects: cabbage 6.22, lettuce 2.79 (both < 10; interpreted as “of concern”)
- Sensitivity analysis: metal concentration in vegetables and body weight were the dominant parameters driving calculated risk
- Health guideline references used: Pb 0.3 mg/kg, Cr 0.5 mg/kg, Cd 0.2 mg/kg, Ni 2 mg/kg (per Alimohammadi et al. 2020)
Methods (brief)
Samples collected from 10 retail vegetable stores (uniform geographic distribution) in Behbahan on two occasions separated by 4 weeks. Samples washed with distilled water, air-dried 24 h at room temperature, then 200 g subsamples were dried at 105°C for 24 h, ground, homogenized, and 500 mg digested with 10 ml HNO3 at 80°C. Digest filtered and adjusted to 25 ml with deionized water; analyzed by ICP. Dry-weight concentrations converted to wet weight using measured moisture content. Risk assessment used standard US EPA equations for EDI, HQ/HI, and ELCR with Monte Carlo simulation (exposure frequency 365 days/year, exposure duration 70 years, BW 70 ± 15 kg). Note: the Cr measured here is total chromium, not Cr-VI; the paper does not speciate chromium, yet applies a carcinogenic slope factor associated with hexavalent Cr (0.5 (mg/kg/day)^-1), which may overestimate risk if Cr in vegetables is predominantly Cr-III.
Implications
Certification: Pb in cabbage (0.312 mg/kg) exceeds the 0.3 mg/kg guideline. Cr values appear high; however, speciation is absent — total Cr cannot be equated with Cr-VI for threshold comparison. These values are from a specific industrial-impact region and should not be treated as representative of global cabbage or lettuce baselines.
Courses: Useful case study on Monte Carlo risk assessment methodology for vegetables from industrialized regions. Demonstrates that non-carcinogenic HI can be below 1 while ELCR is elevated — the two metrics can diverge substantially.
App: Concentration values from this source are region-specific (Khuzestan industrial zone, IR) and should not be used as generic lettuce or cabbage contamination profile values. Flag as high-industrial-impact regional data.
Microbiome: Not applicable directly; no microbiome data.