Groundwater contamination and human health risks from leachate at a decade-closed dumpsite: A case study in Rio de...

Inadequate municipal solid waste disposal can harm environmental and human health due to soil, surface water, and groundwater leachate contamination. This study aimed to assess the effects of leachate from a municipal solid waste dumpsite operational for 24 years (1985-2009) on the quality of surface water and groundwater in the surrounding area. Eight water sampling campaigns were performed over two years (2021-2023) in the dumpsite area, while three groundwater and surface water sampling campaigns were carried out in a downstream residential area. Physicochemical and microbiological quality parameters were evaluated, and human health risks from dermal and oral exposure to carcinogenic and non-carcinogenic metals assessed. Surface water COD and EC values, as well as Cl, Na and Mn concentrations were found to exceed the maximum limits established by legislation. Groundwater samples showed Cl, Na, Fe, Mn and Cr concentrations above guideline values. The spatial distribution of Ca, Cl, Na and Mg concentrations suggests that residential areas closest to the dumpsite continue to be impacted by municipal solid waste contaminants even a decade after the dumpsite's closure. Escherichia coli was detected in 32.5 % of dumpsite and in 40.9 % of residential area groundwater samples. A risk assessment concerning water ingestion in the dumpsite area indicated HQ > 1 for Fe, Na, and Mn, and HQ > 0.0001 for Cr, based on a stringent reference value due to its carcinogenic potential. In the residential area, HQ > 1 was observed for Na and Mn. These findings confirm that the closed dumpsite remains a source of contamination, posing human health and environmental risks and reinforcing the need for appropriate closure and remediation of such sites.