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The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water, sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments are within the range reported for Nigeria's river sediments. Based on this study, the human risks for heavy metals in the harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish.

Phthalate ester plasticizers were determined in rivers and dams of the Venda region, South Africa. Liquid-liquid extraction, column chromatographic clean-up and capillary gas chromatography were the methods used for the quantitative analyses. Levels of phthalates in water samples from the rivers and dams ranged from 0.16 mg/ℓ to 10.17 mg/ℓ and varied between 0.02 mg/kg and 0.89 mg/kg in sediments. Generally, the highest concentrations of phthalates were found as DBP and DEHP, which is consistent with their common use in plastic materials and other industrial chemicals. The phthalate levels found in the water samples were much higher than the criterion of 3 µg/ℓ phthalates recommended by the United States Environmental Protection Agency (USEPA) for the protection of fish and other aquatic life, and higher than the Suggested No-Adverse Effect Levels (SNAEL) of 7.5 to 38.5 µg/ℓ for drinking water. The health risk-assessment studies on the phthalates found in the water systems suggested potential carcinogenic and other toxic effects they may pose to communities downstream which might be exposed either through drinking untreated water from the rivers, through dermal absorption or by using the freshwater sources to water their vegetable gardens. DEHP posed the highest risk potential of all the phthalates and the water use or exposure pathway that appeared to pose the highest potential health risk for carcinogenic as well as toxic effects was vegetable watering. The results for phthalates in the water samples give cause for environmental concern as people's health downstream is at stake if rural populations use this water.

The detection and quantification of four phthalate esters-dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and diethylhexyl phthalate (DEHP)-in water, sediment, and some fish species were carried out using flame ionization gas chromatography. The samples were collected from the Ogun river catchments, Ketu, Lagos. The DMP was not detected in the water and fish samples but was detected in sediments collected from four of the six sampling sites. The concentration of DEP, DBP, and DEHP in the fish species ranged from 320.0-810.0, 380.0-1,080.0, and 40.0-150.0 μg/kg in Tilapia sp.; 310.0-860.0, 400.0-1,170.0, and 40.0-110.0 μg/kg in Chrysichthys sp.; and 320.0-810.0, 400.0-3,970.0, and 30.0-300.0 μg/kg (DEHP) in Synodontis sp.,respectively. The differences in fish phthalate levels are not statistically significant at p < 0.05, an indication that phthalate esters accumulation is not fish species dependent. The DEP, DBP, and DEHP values recorded are considerably higher than the maximum allowed concentrations for drinking water prescribed by the US Environmental Protection Agency. The phthalate pollution index and biosediment accumulation factor values were also calculated.

This study reports the level of total petroleum hydrocarbons (TPH) and trace heavy metals (lead, copper, and cadmium) in soil samples collected randomly from Iyana-Iba garage, Lagos State University bus stop, Adeniran Ogunsanya College of Education bus stop, and a control site off Lusada-Atan road, near Crawford University, Igbesa, Ogun state. TPH was estimated gravimetrically after Soxhlet extraction and column clean up, while soil metals were determined by atomic absorption spectrometry using mineral acid digestion. For TPH, the sites have mean values of 19.43+/-1.27, 16.11+/-1.85, and 11.43+/-4.33 mg/g with a control mean value of 0.33+/-0.16 mg/g. For trace heavy metals, cadmium was not detected. However, the mean levels of lead are 4.24+/-3.10, 3.72+/-0.60, and 3.70+/-1.32 microg/g, respectively, whereas mean copper concentrations are 20.63+/-9.02, 19.35+/-3.61, and 16.76+/-3.02 microg/g in all sites, respectively, compared to the control mean of 0.25+/-0.13 and 5.99+/-1.23 microg/g for lead and copper, respectively. Sites studied have higher levels of TPH and metals compared to the control soil samples. This is indicated by a statistically significant difference found between the concentration of analyzed elements in soils collected along Lagos-Badagry expressway and the control site.