The silent risks of urban lead and its impactful consequences in Boquira, Brazil

Lead (Pb) contamination of urban soils is a global concern due to its toxicity. An example is the municipality of Boquira, Brazil, which between the 1950s and 1990s was the center of intense Pb mining activity and now faces serious soil pollution problems. 3 decades after the closure of mining activities, waste remains close to the urban area. Unfortunately, the local population, unaware of the risks involved, uses this area to waste disposal, resulting in geochemical changes to already dangerous Pb levels. Therefore, the objective of this study is to investigate Pb reactivity, bioaccessibility and potential risks to human health. For chemical fractionation, five composite samples were collected at 6 depths in each of the following areas: Residue (W), Residue under the influence of urban refuse (TW), and Residue under the influence of leachate (LW). For bioaccessibility testing, 10 composite samples were collected at a depth of 0-10 cm around the waste area. Total Pb levels ranged from 15,690 to 30,730 mg kg^- 1, with higher concentrations in leachate influenced tailings and lower concentrations in non-leachate influenced tailings. Total bioaccessible contents reached 11,182 mg kg^- 1, representing 50.83% of total Pb. The main source of Pb from soils is hydrocerussite. The data indicated a high possibility of Pb-induced non-carcinogenic risk for children, and low risk for adults. Carcinogenic risk values of Pb in adults and children exceeded the safety level in almost all samples. Pb exposure can pose significant risks to human health, especially in children.