Galal et al. 2021 — Heavy metals in garden peas from contaminated soils, Egypt
This study measured 12 heavy metals in the roots, shoots, and fruits of garden peas (Pisum sativum) grown at polluted and non-polluted sites in South Cairo and Giza, Egypt. Polluted farms received industrial waste and municipal discharge from the National Cement Company, Egyptian Iron and Steel, brick factories, and Helwan Fertilizer Company. Fruit concentrations in polluted-site peas were dramatically elevated for all metals, particularly Cd (1,025 ± 1.00 mg/kg vs. 2.6 ± 0.14 mg/kg at non-polluted sites) and Pb (121.0 ± 1.32 mg/kg vs. 8.9 ± 1.76 mg/kg). The health risk index (HRI) for Pb, Cd, Fe, and Mn in polluted-site peas exceeded 1, indicating significant consumer health risk.
Key numbers
Heavy metal concentrations in pea fruits (mg/kg dry weight, mean ± SD, Table 3 from source):
- Pb: non-polluted 8.9 ± 1.76; polluted 121.0 ± 1.32 (difference 92.6%)
- Cd: non-polluted 2.6 ± 0.14; polluted 1,025.0 ± 1.00 (difference 99.7%)
- As: non-polluted 0.03 ± 0.00; polluted 0.1 ± 0.01 (difference 50.0%)
- Cr: non-polluted 0.9 ± 0.33; polluted 19.8 ± 0.76 (difference 95.6%)
- Cu: non-polluted 0.4 ± 0.14; polluted 12.6 ± 0.40 (difference 96.7%)
- Ni: non-polluted 0.9 ± 0.38; polluted 24.7 ± 0.76 (difference 96.3%)
- Fe: non-polluted 583.5 ± 45.27; polluted 2,098.0 ± 24.02 (difference 72.2%)
- Mn: non-polluted 10.9 ± 1.94; polluted 61.6 ± 0.79 (difference 82.3%)
- Zn: non-polluted 3.0 ± 4.35; polluted 25.8 ± 1.53 (difference 88.5%)
- Ag: non-polluted 1.5 ± 0.00; polluted 2.2 ± 0.13 (difference 30.2%)
- Co: non-polluted 1.5 ± 0.00; polluted 2.3 ± 0.85 (difference 35.6%)
- V: non-polluted 0.03 ± 0.00; polluted 0.1 ± 0.00 (difference 50.0%)
Polluted soil concentrations (mg/kg): Pb 50.7, Cd 20.4, As 0.6, Cr 0.4, Cu 16.3, Ni 0.6, Fe 171.0, Mn 60.0, Zn 73.0 (Table 1 from source).
HRI >1 in polluted plants for: Pb, Cd, Fe, Mn (for both children and adults); Pb also exceeded HRI of 1 in non-polluted plants for children.
Detection limits (µg/L): Ag 3.0, Fe 5.0, As/Cu/Mn/Zn 1.5, Pb/Cd 15.0, Co 9.0, Cr 3.0, V 2.0, Ni 6.0. Recovery rates 95–104% for SRM 1573a (tomato leaves). Values are dry weight.
Methods (brief)
Plant and soil samples collected winter 2017 from 2 non-polluted and 2 polluted farms (South Cairo and Giza). Plants separated into roots, shoots, and fruits; oven-dried at 105°C; ground to powder; digested by tri-acid mixture (HNO3:H2SO4:HClO4, 5:1:1). 12 heavy metals and K measured by atomic absorption spectrometry (Shimadzu AA-6300). Total N by CHN Elemental Analyzer (Yanako MT-5). Certified reference material SRM 1573a verified accuracy. Paired-samples t-test; ANOVA-2 with DMRT; pollution load index (PLI), bioaccumulation factor (BF), translocation factor (TF), daily intake of metals (DIM), and health risk index (HRI) calculated. Total metals (not speciated for As). Values are dry weight.
Implications
Certification: Directly relevant to the peas ingredient page. These are extreme contamination values from a heavily polluted industrial site; useful as a ceiling/worst-case data point but not representative of commercial pea supply chains. The non-polluted site values (Pb 8.9, Cd 2.6 mg/kg dry weight in fruit) are themselves elevated compared to many supply-chain surveys, likely reflecting regional soil background.
Courses: Useful case study for soil-to-crop transfer of heavy metals and the role of industrial pollution in food contamination.
App: The non-polluted site concentrations could inform a baseline contamination profile for peas, but the study’s purpose is contrasting industrial contamination; commercial supply-chain data would need to be weighed against this.