Potential ecological and human health risks associated with heavy metals in agricultural soils and edible crops of Nagarkanda Bangladesh
Abstract
Heavy metal contamination in agricultural soils and edible crops raises concerns about environmental quality and food safety in Bangladesh. This study investigated arsenic (As), lead (Pb), chromium (Cr), and cadmium (Cd) in 15 paired soil and edible crop samples from Nagarkanda Upazila, Faridpur. Metal concentrations were measured using atomic absorption spectrometry and evaluated through soil contamination indices, ecological risk assessment, soil-to-plant transfer factors, multivariate statistical analysis, dietary health risk assessment and exploratory spatial mapping. Mean concentrations of As, Pb, Cr, and Cd were 36.756, 11.850, 64.933 and 0.373 mg kg⁻¹ in soil, respectively, compared with 0.140, 0.524, 3.675, and 0.0646 mg kg⁻¹ in edible crops. Soil As concentrations exceeded the adopted reference limit while the remaining metals were below their respective limits. The Pollution Load Index (PLI) ranged from 0.857 to 2.020 (mean 1.353 ± 0.291), indicating moderate pollution at 13 sites, heavy pollution at one site and no pollution at one site. The Potential Ecological Risk Index (PERI) ranged from 101.60 to 168.77 (mean 133.05), with 12 sites showing low ecological risk and three showing moderate risk. Cd contributed most to ecological risk and exhibited the highest mean soil-to-plant transfer factor (0.179), followed by Pb (0.061), Cr (0.060), and As (0.004). Principal component analysis showed that the first two components explained 96.8% of the total variance, reflecting differences in metal concentrations across the sampled locations. Dietary risk screening suggested potential health concerns associated with As exposure. Chromium-related estimates, however, represent conservative Cr(VI)-equivalent scenarios because the analysis measured total Cr without distinguishing its chemical forms. Differences between the dry-weight measurements and fresh-weight food standards also limit direct interpretation of dietary exposure. The findings highlight As enrichment and Cd-related ecological risk as important concerns in the sampled agricultural soils. The study provides baseline evidence to guide targeted monitoring and further assessment of soil quality and food safety in Nagarkanda, although broader conclusions require more extensive sampling.