Samma et al. 2024 — Heavy metals in soil and vegetables across Bogura district, Bangladesh
Copper (Cu), chromium (Cr), and lead (Pb) were quantified by atomic absorption spectrophotometry in five vegetable types (potato, tomato, chili pepper, cabbage, cauliflower) and paired surface soils from six upazilas in the Bogura district, Bangladesh’s most industrialized northern city. While Cu concentrations in all matrices remained within BFSA and FAO/WHO safe limits, Cr and Pb in vegetables substantially exceeded permissible levels, with Pb exhibiting a contamination factor greater than 6 (severe contamination category) across most sites. Carcinogenic (CHR > 10⁻⁴) and non-carcinogenic (HI > 1) health risk indices indicated significant risk to consumers across all six upazilas.
Key numbers
Analytical method: AAS (Analytik Jena NovAA 400P); dry weight basis; acid digestion with HNO₃:HClO₄ (2:1) at 180–220 °C. Accuracy recovery 94.7–102.3%; %RSD < 2.9%.
- Cu in vegetables: 3.86–18.55 mg/kg dry weight; all within BFSA limits. Highest in tomato (18.55 mg/kg), lowest in cauliflower (3.86 mg/kg).
- Cr in vegetables: below detection limit to 5.44 mg/kg dry weight; highest in tomato (5.44 mg/kg). Exceeded FSSAI safe limits for multiple vegetables and upazilas.
- Pb in vegetables: potato 5.97–25.77 mg/kg; tomato 3.12–21.69 mg/kg; pepper 4.61–20.58 mg/kg; cauliflower 4.76–22.84 mg/kg; cabbage 6.93–23.28 mg/kg. Pb exceeds Bangladesh Food Safety Authority (BFSA) maximum allowable limit across all vegetable types.
- Pb soil concentrations: 10.42–35.64 mg/kg across vegetable field soils; highest in cabbage fields (35.64 mg/kg).
- Pollution Load Index: Kahaloo and Bogura Sadar upazilas most polluted; Nandigram and Dupchanchia least polluted.
- Bioaccumulation factors (BF) for all metals: < 1, indicating net exclusion from edible plant parts relative to soil; however, absolute concentrations in the edible fractions nonetheless exceed regulatory limits for Pb and Cr.
Methods (brief)
AAS with flame atomization; no speciation (total metals only); dry weight basis. The Pb values are total Pb, not speciated. Quality control via spiked samples. Cr reported as total chromium; no hexavalent chromium speciation performed.
Implications
Certification: Vegetables grown in industrialized agricultural regions of Bangladesh show Pb and Cr contamination substantially above regulatory limits, relevant to ingredient sourcing audit guidance for brands importing Bangladeshi produce.
Courses: Demonstrates urban industrial contamination pathways in vegetable production and the importance of geographic sourcing verification.
App: Potato, tomato, pepper, cabbage, and cauliflower sourced from industrialized agricultural districts in Bangladesh warrant elevated Pb flags.