This study evaluated the occurrence of heavy metals, pharmaceutical residues, and endocrine-disrupting compounds in
Ikot Abasi Estuary, Akwa Ibom State, Nigeria and assessed their ecological and public health implications. Water,
sediment, and fish samples were collected from upstream, midstream, and downstream sections of the estuary. Heavy
metals were determined using atomic absorption spectrophotometry, while pharmaceutical residues and endocrine
disrupting compounds were analysed using high-performance liquid chromatography. The fish samples were examined
for endocrine and histopathological alterations, and parasitological responses, and human health risk was assessed to
determine contaminant levels in the edible fish. The results showed that the concentration of Cd, Cr, Ni, Hg, estradiol,
and ethinylestradiol increased significantly from upstream to downstream. The downstream water contained Pb and Hg
concentrations of 0.056 and 0.006 mg/L, respectively, while sediment concentrations reached 48.9 mg/kg for Pb and 1.04
mg/kg for Hg. Estradiol and ethinylestradiol concentrations downstream were 0.041 and 0.026 µg/L, respectively,
exceeding the recommended. Male fish exposed to the downstream showed marked endocrine disruption at 31%.
Histopathological examination showed severe lesions in the gills, liver, and gonads. Parasite prevalence and diversity
increased significantly with higher contaminant levels. There were strong positive correlations between estradiol and male
vitellogenin (r = 0.91), heavy metals and parasite intensity (r = 0.87), and mercury and hepatic necrosis (r = 0.84). The
assessment of human health risks indicated that the target hazard quotient for lead and mercury was above 1. The total
hazard index was 4.46. Carcinogenic risk values for lead and cadmium exceeded acceptable limits. The study concludes
that Ikot Abasi Estuary is under severe ecological stress due to combined contamination by heavy metals and endocrine
disrupting compounds, with potential consequences for aquatic life and human health.

Keywords: Ikot Abasi Estuary; heavy metals; pharmaceuticals; endocrine disruption; fish pathology; parasites; human
health risk.