Characterization and source assessment of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in sediments of the Fosu Lagoon, Ghana.

The first results ever obtained on polycyclic aromatic hydrocarbon (PAHs) concentrations in the Fosu lagoon surface sediments are presented together with corresponding heavy metal (Fe, Mn, Cd, Zn and Ni) concentrations. Samples collected on a monthly basis from November 2003-April 2004 (Heavy metals) and December 2003-January 2004 (PAHs) at 8 locations, representing different anthropogenic sources of contamination to the lagoon, were analyzed. Concentrations of Cd and Ni in the lagoon sediment suggest greater contamination to the lagoon from industrial activities in the vicinity of the lagoon; 50% of the sediment samples exceeded some established sediment Cd guidelines for the protection of aquatic lives. Then, 15 PAHs were detected among the sediments from the different locations and the compositional pattern in decreasing order was 3-ring > 5-ring > 4-ring > 6-ring > 2-ring PAH compounds. Sigma PAH concentrations in the sediment samples ranged from 254 to 558 mg/kg, with a mean of 359.4 mg/kg. Two distinct areas were identified to be a major source of anthropogenic load of both heavy metals and PAH; the mechanical shop in the northeastern sector of the lagoon is the main location for the input of Cd and it's associated PAH compounds (e.g., acenapthylene, acenaphthene, naphthalene and benzo[a]fluoranthene) and to a lesser extent Ni. Both combustion and petroleum sources may account for PAH loads from this area. The residential area in the northern sector is responsible for high loads of Mn and its associated PAH compounds (e.g., phenanthrene, benzo[a]pyrene and anthracene). These chemicals seem to enter the lagoon mainly by the combustion of especially wood or coal.

Cancer and non-cancer health risk from eating cassava grown in some mining communities in Ghana.

Food crops such as cassava, cocoyam and other tuber crops grown in mining communities uptake toxic or hazardous chemicals such as arsenic, and cadmium, from the soil. Cassava is a stable food for Ghanaians. This study evaluated human health risk from eating cassava grown in some mining communities in Ghana such as Bogoso, Prestea, Tarkwa and Tamso, which are important mining towns in the Western Region of Ghana. The study evaluated cancer and non-cancer health effects from eating cassava grown in the study areas in accordance with US Environmental Protection Agency's Risk Assessment guidelines. The results of the study revealed the following: cancer health risk for Tamso, 0.098 (RME--Reasonable Maximum Exposure) and 0.082 (CTE--Central Tendency Exposure). This means that approximately 10 and 8 out of 100 resident adults are likely to suffer from cancer related cases by RME and CTE parameters respectively. For Prestea, we have 0.010 and 0.12, which also means that approximately 1 out of 100 and 10 resident adults out of 100 are also likely to suffer from cancer related diseases by RME and CTE parameters. The results of the study obtained were found to be above the acceptable cancer risk range of 1x 10(-6) to 1x 10(-4), i.e., 1 case of cancer out of 1 million or 100,000 people respectively.

Non-cancer health risk assessment from exposure to cyanide by resident adults from the mining operations of Bogoso Gold Limited in Ghana.

Cyanide is a very toxic chemical that is used to extract gold from its ores. Wastewaters from gold mining companies such as Bogoso Gold Limited (BGL) contain cyanide and other potentially toxic chemicals that have adverse effects on human beings and aquatic organisms. This study was conducted to evaluate the human health risk assessment from exposure to free cyanide via oral and dermal contact of surface/underground water by resident adults within the concession of Bogoso Gold Limited. The chronic non-cancer health risk from exposure to cyanide in River Bogo Upstream is 230 and 43 (by Central Tendency Exposure (CTE) parameters respectively). This means that approximately 230 and 43 resident adults are likely to suffer diseases related to cyanide intoxication via oral and dermal contact respectively. For chronic exposure to River Bogo Downstream by resident adults, the non-cancer health risks are: 0.031 and 0.57 via oral and dermal contact for CTE parameters respectively, which also means that, the non-cancer health risks associated with cyanide intoxication is negligible as the hazard index is less than 1.0 via oral and dermal contacts respectively. The results showed that health risk for acute exposure to cyanide by the resident adults is very high. Hence the residents attribute most of the unexplained deaths in the communities to accidental ingestion and dermal contact of cyanide water.

Quality of "sachet" waters in the Cape Coast municipality of Ghana.

To determine the quality of sachet water samples in the Cape Coast municipality of Ghana, random sampling procedures were used to collect 180 samples from 29 brands produced in the municipality from 1999 to 2004. For any particular year, each tested brand was sampled three times at intervals of not less than 2 weeks (usually monthly) between the months of March to June. Forty-five percent (45%) of the brands subjected to bacteriological examination contained coliform bacteria for one sampling period or another during the period of investigation. The coliform contamination seemed to be more prevalent with some particular brands. Three out of seven brands examined in 2004 also recorded the presence of E. coli. Exceedances were recorded for WHO drinking water quality guidelines for pH (6.25-7.93) in 2002 and for conductivity (67-306 microS cm(-1)) in 2002 and 2004. Total hardness values for all sachet water brands were less than 100 mg/l CaCO(3) and therefore below the WHO limit for potable water. None of the samples seems to pose any health dangers as far as the major cations; sodium (17.4-19.1 mg/l), potassium (5.7-6.2 mg/l), calcium (8.0-24.0 mg/l) and magnesium (19.9-50 mg/l) are concern. Apart from nitrite, for which some exceedances were recorded and phosphate which does not have an established WHO guideline, the measured major anions (i.e., chloride: 1.57-37.7 mg/l, sulfate: 0.33-44.33 mg/l and nitrates: 0.005-0.70 mg/l) were within the WHO drinking water guideline. No exceedances were also recorded for iron and lead. In general, the high quality claimed for sachet waters could not be confirmed based on the measured physico-chemical and bacteriological properties. The variable quality and in some cases, poor water quality observed, likely reflects the fact that the sachets are not always bagged under scrutinized sanitary conditions.