Assessing risks of methylmercury contamination in the Ankobra estuary, Western Region, Ghana

Heavy metal contamination in coastal waters is a global concern, with mercury being among the most persistent pollutants. Methylmercury (MeHg), the most toxic form of mercury, poses serious neurological, cardiovascular, and other health risks to humans. This study assessed MeHg levels in the lower Ankobra River and estuary and evaluated the ecological and health risks (Er and THQ) for the Sanwoma community in the Western Region of Ghana. Sediment samples (n=10) and fish tissues (n=8) were analysed using Cold Vapour Atomic Absorption Spectrometry (CVAAS). A survey of 100 residents assessed the frequency of fish consumption. MeHg concentrations in sediments ranged from 22.00 ± 4.20 to 61.00 ± 0.14 μg/kg, below the World Health Organization (WHO) limit of 200 μg/kg. MeHg in fish ranged from non-detectable to 352.30 ± 2.40 μg/kg, below the WHO limit of 500 μg/kg. However, Channa striata (176.90 ± 2.60 μg/kg) and Mugil bananensis (352.30 ± 2.40 μg/kg) exceeded the United States Food and Drug Administration (US FDA) safety limits for frequent consumption. Although the Er and THQ indicated low risk, frequent consumption of these species may pose health risks, particularly to vulnerable groups such as children and pregnant women. Continuous monitoring and intervention are recommended to reduce MeHg exposure and protect ecosystem and public health.