Human health risk assessment from potentially toxic elements in the soils of Sudan: A meta-analysis

Potentially toxic elements (PTEs) in soils threaten human health through several exposure pathways. However, health risks posed by PTEs in soils in developing countries have not yet been comprehensively investigated. Thus, such countries lack important information that is needed to implement sustainable solutions. In this study, we assessed the human health risks for 10 PTEs, including arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn), in Sudan focusing on soils affected by anthropogenic activities, such as industrial processes, gold mining, tannery, waste dumping, traffic (affecting roadsides), urban/rural agriculture, river, and coastal sediment land uses (LUs). For this purpose, we did a meta-analysis using 3430 PTE concentrations reported from 981 anthropogenically-affected soils in 76 publications between 1996 and 2024. Ingestion was the most common exposure pathway for both carcinogenic and non-carcinogenic PTEs. Hg and Mn were the main non-carcinogenic PTEs leading to adverse health effects in children in industrially-affected soils and coastal sediments, with average hazard quotient (HQ) and hazard index (HI) values >1. Cr and Ni caused the highest carcinogenic risk to children in all anthropogenically-affected soils as indicated by average incremental lifetime cancer risk values (ILCR >1 × 10^-4). Further major cancer risks for children were caused by As in urban agricultural and industrial LUs, Cd in >70 % of all LUs, and Pb at industrial and waste dump sites. Adults were under high cancer risks due to Cd in waste dump (ILCR = 9.09 × 10^-4) and Cr and Ni (ILCR >1 × 10^-4) in >75 % of all LUs. Cd contributed >50 % and >70 % to ILCR for children and adults along roadsides, respectively. Our findings can guide future research on the links between soil PTEs and human health risks in developing countries. We recommend establishing effective management strategies to reduce risks to human health based on the presence of PTEs in Sudanese soils.