Al Zabadi et al. 2018 — Cd, Pb, Cu, and Zn in Palestinian canned foods
This study assessed Cd, Pb, Cu, and Zn in 16 canned food samples (beans, chickpeas, corn, mushroom) sold in the Palestinian market using flame atomic absorption spectrometry (FAAS). The key finding is that cadmium and copper concentrations exceeded WHO-derived maximum permissible limits in several samples, with canned beans showing the highest Cd (0.322 mg/L) and canned mushrooms having the highest Cu. Lead was generally within permissible limits, except for one canned corn sample. The results raise concern about canning-process contamination and insufficient supply-chain controls in the Palestinian market context.
Key numbers
Concentrations in mg/L (as detected in homogenized sample solution):
Cadmium (Cd) — range 0.019–0.322 mg/L across all 16 samples:
- Highest: canned beans (“Kaseeh” brand) = 0.322 mg/L; other bean brands: 0.23 mg/L
- Canned chickpeas: Americana 0.208 mg/L, Kaseeh brand elevated
- Canned corn and mushroom: low or not detected
- Maximum permissible limit used by authors: 0.006 mg/L — exceeded in beans and chickpeas
- Note: the 0.006 mg/L limit cited by authors is unusually low and may reflect Palestinian Authority or WHO water-quality standards rather than food standards; EU ML for Cd in canned legumes is 0.1 mg/kg (wet weight); unit reconciliation required before direct comparison with regulatory standards
Lead (Pb) — range 0.089–1.17 mg/L:
- Canned corn: highest average Pb concentration; one “marina corn” sample exceeded the permissible limit
- Beans: lowest Pb average
- Chickpeas and mushrooms: similar intermediate levels
- Maximum permissible limit used by authors: 1 mg/L — generally met except marina corn
Zinc (Zn) — range 2.05–10.6 mg/L; within limits Copper (Cu) — range 0.79–3.97 mg/L; exceeded author’s 0.9 mg/L reference for several samples
Sample size note: n=16 is small; 4 brands per product type. Results are indicative rather than representative of the market distribution.
Unit note: Concentrations reported in mg/L from solution analysis, not mg/kg wet weight. Direct comparison with food-matrix regulatory limits (mg/kg wet weight) requires conversion based on sample preparation dilution factor (5 g in 50 mL, = 0.1 g/mL), implying multiply by approximately 10 to convert mg/L to mg/kg. On this basis, Cd in highest bean sample ≈ 3.22 mg/kg — substantially above EU ML of 0.1 mg/kg and raising concern about analytical methodology or contamination in that specific sample.
Methods (brief)
FAAS (IcE-3000 Series, Thermo Fisher). Samples (5 g) digested with concentrated HNO3 + H2SO4, diluted to 50 mL. Standard curves for Cd, Pb, Zn, Cu. The paper does not report LOD/LOQ values explicitly. No speciation performed. The concentration unit (mg/L) is from the digestion solution, not mg/kg food; see unit note above.
Implications
Certification: The extremely high Cd values in canned beans, if confirmed on a mg/kg basis, would indicate severe contamination that far exceeds any known regulatory limit. The unit ambiguity and lack of LOD reporting limit confidence in these specific findings. This source should be used with caution as a secondary reference; heavier reliance on sources with explicit mg/kg reporting and validated LODs is recommended for the beans/chickpeas contamination profile. The signal that canning-process contamination is a variable (from solder, can coating) is relevant to product-category risk assessment.
Courses: Demonstrates the importance of unit clarity and proper LOD/LOQ reporting in food safety publications; useful cautionary methodological example.
App: Use with caution given unit ambiguity. Not recommended as a primary source for quantitative app-facing exposure estimates without unit reconciliation.