Seasonal Occurrences and Risk Assessment of Phthalate Esters in Sediment, Water and Biota of Two Sub-Saharan Rivers.

The global environmental occurrence of phthalates is inevitable due to their substantial annual production and consumption rate of approximately 5 million tonnes. This study aimed to evaluate the seasonal occurrence of selected phthalate esters congeners in sediment, water, and biota in two freshwater bodies (River Owena and River Ogbese) in Nigeria, and to calculate their ecological risks they pose to aquatic organisms. Dibutyl-phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and dimethyl-phthalate had an all-year presence in various environmental matrices. DBP was the most prevalent phthalate congener in all environmental matrices with a considerable potential to bioaccumulate in fish tissues. The estimated risk quotient calculated revealed that DBP and DEHP showed a high risk to algae, invertebrates, and fish populations in both freshwater bodies. It is recommended that more comprehensive monitoring campaigns in freshwater bodies be implemented, especially in areas with high anthropogenic activities, to prevent deterioration of aquatic life.

Bioaccumulation of Polychlorinated Biphenyls (PCBs) in Fish Host-Parasite Bentho-Pelagic Food Chain in Epe Lagoon, Lagos, Nigeria.

This paper investigates the concentrations of PCBs in the water and sediment media and its bio-concentration in the fish host-parasite bentho-pelagic food chain in Epe lagoon. Samples of water, sediment, plankton, mollusks, fish and intestinal helminth parasites were collected from three stations (Oriba, Imode and Ikosi) in Epe Lagoon. Concentration of total PCBs in the surface water and sediment across the stations ranges from 3.20 to 6.00 ppb and 405.50-860.70 ppb respectively. Imode had the highest concentrations. The plankton bio-concentrates most PCBs in Ikosi (286.70 ppb) followed by Imode concentration (165.40 ppb), then Oribo (92.60 ppb) with total bio-concentration of 544.60 ppb. Surface water temperature negatively and strongly correlates with PCBs in the plankton. The planktons bio-concentrates total PCBs 44 times than that in the surface water. Chrysichthys nigrodigitatus bio-concentrates total PCBs 48 times than that in the surface water. Bioaccumulation of PCBs in human food chain could pose health risk.

A computational analysis of the molecular mechanisms underlying the effects of ibuprofen and dibutyl phthalate on gene expression in fish.

The impact of emerging pollutants such as ibuprofen and dibutyl phthalate on aquatic species is a growing concern and the need for proper assessment and evaluation of these toxicants is imperative. The objective of this study was to examine the toxicogenomic impacts of ibuprofen and dibutyl phthalate on Clarias gariepinus, a widely distributed African catfish species. Results showed that exposure to the test compounds caused significant changes in gene expression, including upregulation of growth hormone, interleukin, melatonin receptors, 17ß-Hydroxysteroid Dehydrogenase, heat shock protein, doublesex, and mab-3 related transcription factor. On the other hand, expression of forkhead Box Protein L2 and cytochrome P450 was downregulated, revealing a potential to induce female to male sex reversal. The binding affinities and hydrophobic interactions of the test compounds with the reference genes were also studied, showing that ibuprofen had the lowest binding energy and the highest affinity for the docked genes. Both compounds revealed a mutual molecular interaction with amino acids residues within the catalytic cavity of the docked genes. These results provide new insights into the toxic effects of ibuprofen and dibutyl phthalate on Clarias gariepinus, contributing to a better understanding of the environmental impact of these pollutants.

Chronic levels of ibuprofen induces haematoxic and histopathology damage in the gills, liver, and kidney of the African sharptooth catfish (Clarias gariepinus).

Numerous active pharmaceutical ingredients (APIs) have been detected in various environmental matrices. Thus, their potential to elicit their toxic effect on non-target organisms is a growing concern, especially in the aquatic environment. This study aimed to investigate the potential toxicity of ibuprofen (IBU) at environmentally relevant concentration on the haematology and histology of the gill, liver, and kidney over 30 days. The 96-h acute toxicity data showed that IBU was moderately toxic to C. gariepinus with an LC50 value of 3.78 mg/L. After 15 and 30 days of exposure, there was a significant alteration in haematological indices in the treated fishes when compared to the control group. Throughout the experimental duration, the level of the mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) were consistently lower significantly, in contrast to the control group. IBU induced histopathological deformities in the gills, liver, and kidney of the exposed fishes, with alterations such as showing severe secondary lamella necrosis (SLN), epithelial lifting (EL), mild deformity of the secondary lamella (DSL), mild secondary lamella necrosis (MLN), and mild vascular congestion in the liver and kidney, respectively. This study has demonstrated that IBU at environmentally relevant concentrations can significantly impact the haematology, gills, liver, and kidney of C. gariepinus. This study's results can provide baseline info for regulatory agencies to set safe limits for NSAIDs as a safeguard for the aquatic environment.

Biochemical Effects of the Toxic Interaction of Copper, Lead and Cadmium on Clarias gariepinus.

BACKGROUND: The presence of heavy metals in the aquatic environment is a concern because of potential toxicity and threats to plant and animal life. OBJECTIVE: The present study evaluated the joint action toxicity and biochemical effects of sublethal concentrations of copper (Cu), lead (Pb) and cadmium (Cd) against Clarias gariepinus over a period of 28 days. METHODS: We procured fingerlings (weight: 5-8 g; length: 4.5-6.0 cm) and juveniles (weight: 20-25 g; length: 14.5-17.5 cm) from a commercial fish farm in Bariga, Lagos state, Nigeria. Test toxicants were selected from the analyzed heavy metals in the field based on their deviation from World Health Organization, Federal Environmental Protection Agency and United States Environmental Protection Agency standards. Fish were randomly loaded into a 4-L glass aquaria for the bioassay per toxicant concentration of two replicates and untreated control (dechlorinated tap water). RESULTS: The derived 96 hour lethal concentration 50 (LC50) value of Cu (2.11 mg/L) was the most toxic followed by Cd (24.18 mg/L) and Pb (34.48 mg/L), which was the least toxic of the singly tested pollutants. The analysis of dose-response data of the joint action toxicity of Cu and Cd, and Cu and Pb determined 96 hour LC50 values of 1.804 mg/L and 2.15 mg/L, respectively. The interactions between the mixture of Cu:Cd conformed with the model of synergism (synergistic ratio (SR)>1 and relative toxic units (RTU)>1), while the interaction between Cu:Pb was found to be antagonistic (SR<1), with an SR value of 0.98. The biochemical effects study revealed that malondialdehyde (MDA) levels decreased significantly (P<0.05) in the exposed fish, reduced glutathione was not significant at (P<0.05), and levels of superoxide dismutase (SOD), catalase, glucose and cholesterol were significantly different (P<0.05). DISCUSSION: The observed increased in the glutathione level in the Cu:Cd mixture and a corresponding decrease in MDA concentration in the liver of test animals revealed the ability of fish to overcome the effects of lipid peroxidation in this group because the Cu ion is displaced by Cd, and the fish were able to catalyze the breakdown of hydrogen peroxide via the Fenton reaction. CONCLUSIONS: Further studies on the joint action toxicity of heavy metals are needed in order to further determine their concentration in the local environment. ETHICS APPROVAL: Study protocols were approved by the Health Research Ethics Committee of the University of Lagos.