Human exposure to mercury, lead and cadmium through consumption of canned mackerel, tuna, pilchard and sardine.

Total mercury (Hg), cadmium (Cd) and lead (Pb) concentrations were determined in canned fish on the Ghanaian market. Total mercury was determined using an automatic mercury analyzer while cadmium and lead levels were determined by flame atomic absorption spectrophotometry. The metal contents in the samples, expressed in µg g(-1) (wet weight), varied from <0.01 to 0.20 with an average value of 0.03 for mercury, from <0.01 to 0.45 with an average value of 0.34 for cadmium, and from <0.01 to 1.44 with an average value of 0.72 for lead. The results indicate that canned fish from the Ghanaian market have concentrations well below the permissible FAO/WHO for these toxic metals. Thus considering the Provisional Tolerable Weekly Intake (PTWI) of Hg, Pb and Cd the levels obtained in this study are unlikely to constitute a significant exposure to the public through consumption of moderate amounts.

Levels of total mercury in different fish species and sediments from the Upper Volta Basin at Yeji in Ghana.

In this study, total mercury concentrations were determined in sediments and seven different fish species from the Upper Volta Basin area of Yeji in Ghana. Mercury concentrations found ranged from 44.17 to 85.88 ng/g wet weight for Synodontis gambiesis, from 11.25 to 79.73 ng/g wet weight for Synodontis membranaceus, from 13.11 to 38.64 ng/g wet weight for Synodontis ocellifer, from 16.39 to 25.82 ng/g wet weight for Distishodus rotratus, from 40.80 to 90.30 ng/g wet weight for Bagrus docmac, from 10.48 to 61.90 ng/g wet weight for Chrysichthys nigrodigitatus and from 12.33 to 24.18 ng/g wet weight for Gnathoneus senegalensis. These values are below the 500 ng/g guideline recommended by the WHO/FAO, implying that fish from the Upper Volta Basin area of Yeji are safe for human consumption. Good correlation was observed between mercury concentration and fresh weight (R(2) = 0.6067) and total length (R(2) = 0.8754) for Gnathonemus senegalensis. However, poor correlations were observed between mercury concentration and fresh weight and total length for the other six species. Mercury in sediments ranged from 11.87 to 70.25 ng/g dry weights with a mean of 41.60 ng/g dry weight being below the IAEA threshold of 810 ng/g.. These values show that sections of the Upper Volta River remain relatively clean in spite of substantial loadings of mercury into the river's basin from gold mining activities.

Total mercury in fish, sediments and soil from the River Pra Basin, southwestern Ghana.

Total Mercury (Hg) concentrations were determined in soil, river sediments and six (6) species of fish from the River Pra Basin in southwestern Ghana by Cold Vapour Atomic Absorption Spectrometry. Mercury concentration (microg g(-1)) ranged from 0.042 to 0.145 for soil: from 0.390 to 0.707 for sediments and from <0.001 to 0.370 for fish. All the fish samples had Hg concentration below the World Health Organisation (WHO) permissible limit of 0.5 microg g(-1) whereas all the sediment samples had levels higher than the US-EPA value of 0.2 microg g(-1). The results obtained from this study showed that fish from River Pra Basin are unlikely to constitute any significant mercury exposure to the public through consumption. No apparent trend of increasing mercury concentration along the main river as it flows downward toward the sea was observed.