Vanisree et al. 2022 — Heavy metal contamination of food crops: transport, toxicity, and management (IntechOpen chapter)
This book chapter, published in an IntechOpen edited volume on Environmental Impact and Remediation of Heavy Metals, covers the transport of heavy metals from soil and irrigation water into food crops, the toxicity mechanisms following human consumption, and management strategies to reduce contamination. The chapter draws on studies from Bangladesh, India, and globally, with a focus on agricultural contamination pathways: industrial effluents, mine tailings, leaded fuels and paints, agricultural chemicals, and wastewater irrigation. It presents a table of Pb, Cr, and Cd concentrations in effluent-contaminated irrigation water from the Dhaka Export Processing Zone (DEPZ), Bangladesh (Pb mean 0.21 mg/L, Cr mean 0.43 mg/L, Cd mean 0.06 mg/L against respective safe limits of 0.5, 0.1, and 0.01 mg/L), providing a concrete example of how industrial discharge exceeds safe limits for Cr and Cd in agricultural water. The chapter does not present primary food concentration data; it reviews the mechanisms by which soil and water contamination translates into crop accumulation.
Key numbers
Effluent-contaminated irrigation water from Bangladesh DEPZ (Table 1 in chapter, from cited source [21]):
- Pb: mean 0.21 mg/L (safe limit 0.5 mg/L) — within limit
- Cr: mean 0.43 mg/L (safe limit 0.1 mg/L) — 4.3× above limit
- Cd: mean 0.06 mg/L (safe limit 0.01 mg/L) — 6× above limit
These are water concentrations, not food concentrations; they illustrate the contamination source pathway, not the endpoint concentration in food.
General patterns cited from reviewed literature:
- Root > leaf > stem > grain metal concentration gradient in most crops
- Bangladesh vegetables from DEPZ had elevated Cr, Zn, Cu, Fe, Pb, Ni, Cd
- Rice and wheat Cd: accumulation linked to flooded paddy conditions
- Medicinal plant species near smelters show bioaccumulation of Cd, As, Cr, Cd, Cu, Pb, Fe
Methods (brief)
Narrative review chapter. No primary data generated. IntechOpen open-access chapter DOI: 10.5772/intechopen.101938. Evidence tier B: book chapter, useful for mechanistic background on soil-to-crop metal transport and for the DEPZ irrigation water data point. The DEPZ irrigation water values trace to a cited primary study [21] which should be consulted for full methodology.
Implications
Certification: Provides mechanistic background for HMT&C supply-chain ingredient origin screening rationale. The Bangladesh wastewater irrigation data supports the principle that geographic origin is a legitimate screening criterion for ingredient sourcing.
Courses: Good supply-chain module reference for the soil-to-plant uptake section. The root > leaf > stem > grain gradient is a useful teaching point for explaining why polishing reduces arsenic in rice but does not eliminate it entirely.
App: Not a source of food concentration values. Qualitative flag: Bangladesh origin + industrial proximity is elevated risk for Cd, Cr, Pb.