Metal uptake in sweet peppers cultivated in soils contaminated by artisanal gold mining: implications for food safety

Soil contamination by metals poses a significant threat to food safety and human health, particularly through the consumption of vegetables cultivated in mining-impacted areas. In Colombia, gold mining and horticultural activities frequently coexist; however, information on the uptake of mining-associated metals by edible crops and the resulting health risks remains limited. This study investigated the accumulation of mercury (Hg), lead (Pb), and arsenic (As) in sweet pepper (Capsicum annuum) cultivated in soils affected by gold mining and evaluated the potential human health risks. A single-factor experimental design was employed using soils collected at three distances from active mining sites (S1: 0.6 km, S2: 3 km, and S3: 20 km). Plants were grown under screen-house conditions for 143 days, during which morphometric, physiological, and chemical analyses were performed. Soil concentrations of metals decreased with increasing distance from mining activity: S1 (Hg: 22.13, Pb: 1997.02, As: 37.52 mg kg^-1), S2 (Hg: 5.38, Pb: 186.03, As: 15.70 mg kg^-1), and S3 (Hg: 2.05, Pb: 57.19, As: 7.90 mg kg^-1), with generally low bioavailability (Hg and As < 1%; Pb: 2-11%). Metal accumulation occurred predominantly in roots, with limited translocation to aerial and edible tissues. Bioconcentration factor (BCF) and translocation factor (TF) were consistently below unity, indicating limited uptake and internal transfer of Hg, Pb, and As. Human health risk assessment based on Codex Alimentarius provisional tolerable weekly intake (PTWI), margin of exposure (MOE), total hazard quotient (THQ), and incremental lifetime cancer risk (ILCR) indicated low non-carcinogenic risk and negligible carcinogenic risk at distances of 3 and 20 km. Although Hg concentrations exceeded the limits established by the Chinese National Food Safety Standard (GB 2762-2022), which sets a threshold of 0.1 mg kg^-1, the overall results suggest no immediate health risk from consumption. Nevertheless, considering the persistence and bioaccumulative nature of these elements, long-term exposure risks cannot be excluded, highlighting the need for continuous monitoring of agricultural systems in mining-influenced regions.