Metal(loid)s Contamination in the Soil-Rice System: Health Risk Assessment Based on Source Analysis and Monte Carlo...

Metal(loid)s contamination in rice-growing systems poses substantial concerns for food safety and human health, particularly in agro-industrial regions where industrial discharge and agricultural inputs may elevate contamination levels. However, comprehensive investigations integrating source apportionment, probabilistic health risk assessment, and uncertainty analysis in the soil-rice system remain limited in Pakistan. Therefore, this study aimed to determine the concentrations, spatial distribution, pollution status, potential sources, and human health risks associated with metal(loid)s (copper, manganese, chromium, barium, arsenic, mercury, cadmium, and lead) in paired soil-rice samples collected from major rice-growing industrial regions of Punjab, Pakistan. A total of 60 paired soil-rice samples were analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES), whereas pollution indices, positive matrix factorization (PMF), principal component analysis (PCA), hierarchical cluster analysis (HCA), GIS mapping, and Monte Carlo simulation (10,000 iterations) were employed for source identification and probabilistic health risk assessment. Soil contamination assessment indicated elevated contamination by Cu (CF = 17.15; I_geo = 2.88), with an overall high ecological risk (RI = 332.48) and pollution load index (PLI = 2.65). PMF and multivariate analyses identified three major contamination sources, primarily associated with industrial emissions, agricultural inputs, and mixed geogenic-anthropogenic contributions. Despite localized contamination hotspots near industrial drains, estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI < 1), carcinogenic risk (CR), and cumulative cancer risk (CCR < 10^-3) for both adults and children remained within acceptable safety thresholds under Monte Carlo uncertainty analysis. These findings provide an important baseline for source-oriented environmental management and support sustainable agricultural and industrial practices to minimize long-term metal(loid)s exposure risks in rice-growing regions.