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Fish and shellfish are regularly consumed and sold in Ghana, yet studies on arsenic pollution in Ghana are limited largely to ground water. This study evaluated arsenic concentrations in seven species of shellfish and 10 species of fish inhabiting the mouth of Ankobra, Densu and Volta basins in Ghana and assessed the public health implications. Arsenic levels varied from 0.2 to 2.2 mg L -1 in the three rivers and were higher than WHO recommended values of 10 μg L -1 for drinking water. Except for Periophthalmus sp. and Tympanotonus fuscatus from the Ankobra in which arsenic was not detected, concentrations in the organisms ranged from 0.2 to 2.8 mg kg -1 . The maximum quantities of the organisms considered safe for consumption ranged from 375 to 5250 g per week. Caution however needs to be exercised as PTWI for arsenic needs revision, and some heavy metals such as mercury are more toxic than arsenic.

Crustaceans, mollusks, and fish are wetland resources that constitute an important source of protein and foreign exchange for the Ghanaian population, and many species of these are sold in the open market and restaurants, yet studies on their heavy metal contents are generally scarce. This paper evaluates the levels of mercury in five species of crustaceans, two species of mollusks, and ten species of fish inhabiting three river basins with different catchment activities in Ghana. These include the Ankobra Basin, characterized with mining and agriculture, Densu Basin, associated with urban waste discharges and agriculture, and Lower Volta River Basin, associated with agricultural activities. Mercury concentration was highest in Ankobra (2.5 ± 2.59 μg g -1 ) followed by Densu (1.75 ± 1.35 μg g -1 ) and Volta (0.74 ± 1.46 μg g -1 ). The mercury load of the organisms range from <0.1 to 4 μg g -1 with the highest load in Cynoglossus senegalensis at Ankobra. Except for Panaeus notialis from Densu and Ankobra, and three other species from Ankobra (Tympanotonus fuscatus, Cardisoma armatum, Callinectes amnicola) in which mercury was not detected, mercury loads of all the organisms were above the permissible limit of 0.5 mg kg -1 established by Commission Regulation-EC (2006) for fishery products and muscle meat of fish. Weekly quantities of crustaceans and mollusks considered safe for consumption by adults ranged from 88 and 1000 g while that of the fishes were between 70 and 700 g (on a dry weight basis) depending on the species. It was clear that some caution needs to be exercised in the consumption of Ghana's fresh and brackish water fisheries.