Ecological and human health risk due to heavy metals and trace elements contamination in produced water from basins oil fields in Chad

Abstract This study assesses the presence and possible ecological and human health concerns associated with possibly toxic heavy metals and trace elements in produced water collected from the Badila and Benoye oil fields (Doba Basin) and the Ronier oil field (Bongor Basin), in southern Chad. The water samples were analyzed using inductively coupled plasma mass spectrometry. The measured concentrations (µg L − 1 ) ranged as follows: Cd (0.01–0.11), Co (0.07–9.6), Ni (0.4–3.0), Pb (0.01–27), Cu (3.2–33), As (0.2–86), Zn (0.9–147), Cr (10–823), Ba (12.4–577), Mn (5.8–901), Al (2.1-59710), and Fe (37–875900). The contamination levels were assessed by comparing them to WHO international drinking-water guidelines, rather than by implying direct consumption. The guideline values were exceeded by a substantial number of samples, with Fe (58%), As (42%), Al and Mn (28%), and Pb (28%) exceeding them. The risk quotient approach was employed to conduct an ecological risk assessment, which revealed that the majority of elements were at a low risk. However, Fe was found to have a high potential for ecological concern. Hazard index values of 15 (children) and 10 (adults) were obtained from a hypothetical worst-case exposure scenario (ingestion and dermal contact) in the context of human health risk assessment. These values indicate that there may be potential non-carcinogenic risks under extreme exposure conditions. The cancer risk (CR) values exceeded the permissible threshold, ranging from 4 × 10 − 3 to 5 × 10 − 3 . These results offer baseline data on the quality of produced water in southern Chad; however, they should be interpreted with prudence due to the absence of speciation and dilution considerations and the assumptions regarding exposure pathways. The study underscores the necessity of enhanced monitoring and administration of produced water in oil-producing regions. These findings establish baseline data for produced water quality in southern Chad; nevertheless, the results must be interpreted cautiously due to assumptions about exposure pathways and the absence of speciation and dilution considerations. The study highlights the need for improved monitoring and management of produced water in oil-producing regions.