Background. Polycyclic aromatic hydrocarbons (PAHs) are toxic contaminants and pose health risks to humans and the ecosystem due to their persistence in the environment. Objectives. This study determined the concentrations of PAHs in sediment, two species of fish (Drepane africana and Pomadasys jubelini), crabs (Callinectes amnicola) and shrimps (Penaeus notialis) around the Atlas Cove jetty, Lagos, Nigeria. Methods. Polycyclic aromatic hydrocarbons were extracted from fish, shrimp, and crabs that were purchased from local fishermen. Sediments were collected at five locations impacted by ship movement and cargo offloading around the Atlas Cove jetty during the period of June to August 2016, using standard methods. Potential toxicity of PAHs in the sediments on the surrounding aquatic organisms was assessed. The PAHs were analyzed using gas chromatography-mass spectrometry. Human health risk assessment was calculated from biota using dietary daily intake and carcinogenic potencies of individual PAH concentrations. Results. A total of 17 PAH congeners were detected in sediment samples and ten were detected in biota samples. Concentrations of total PAHs obtained in sediment and fish samples ranged from 2.15 - 36.46 mg/kg and 11.89 - 71.06 mg/kg, respectively. The total PAHs concentration pattern follow the order of P. notialis > C. amnicola > P. jubelini (whole) > D. africana (whole) > D. africana (fillet) > P. jubelini (fillet) > sediment. Concentrations of total PAHs were higher in whole fish than in fillet samples (muscle) in both fish species. High values of PAHs were recorded in the dietary intake (0.10 - 2.33 mg/kg body weight/day) of the organisms. Toxic equivalent quotient values (0.01 to 0.10 mg/kg) were observed to be higher than the screening values (0.0014 to 0.0599 mg/kg). In the muscle of Drepane africana and Pomadasys jubelini, splitting and atrophy of the muscle bundles were observed. Conclusions. The concentrations of PAHs in analyzed sediment and organisms were higher than the maximum permissible limit of the United State Environmental Protection Agency (USEPA). Most of the detected PAHs were of petrogenic origin, which is an indication that anthropogenic activities were influencing PAH concentrations. Competing Interests. The authors declare no competing financial interests.

This study assessed the effect of heavy metals introduced into the soils through human activities which can bio-accumulate in plants and passed to man via the food chain that can pose health risk. Topsoil samples were collected from selected anthropogenic and control sites (dumpsites, mechanical workshops, abattoirs, fuel filling stations and hospital incinerators) in Abeokuta, Nigeria at the depths 0-5cm, 5-10cm and 10-15cm. Physicochemical parameters such as pH, moisture content, bulk density, organic matter, organic carbon, particle size distribution and Mn, Zn, Pb, and Cd were analyzed in soils using standard methods. Soil pH values ranged from 5.17 -8.28, moisture content ranged from 3.50 -28.55 %, bulk density ranged from 0.78 -2.29 gcm -3 , organic matter ranged from 0.09 -16.01 %, organic carbon ranged from 0.02 % -8.48 %. Mean concentrations of heavy metals (mgkg -1 ) ranged from 182.69 ± 61. 95 -697.06 ± 85.62; 122.69 ± 30.04 -632.94 ± 508.79; 19.38 ± 6.72 -158.50 ± 71.41; 0.25 ± 0.00 -1.63 ± 1.38 for Mn, Zn, Pb and Cd respectively. Distribution pattern of heavy metals in petrol stations, abattoirs, mechanic workshops and hospital incinerator sites were Mn > Zn > Pb > Cd, while for dumpsites Zn > Mn > Pb > Cd. Pollution index indicated that soil qualities varied between slightly contaminated to severely polluted status. This showed that the heavy metal contamination of the soils does not call for any alarm; proactive measures must be taken to minimize accumulation of these metals. ©JASEM https://dx.doi.org/10.4314/jasem.v21i5.14

Background. Soil pollution by heavy metals in urban areas is of major concern to city planners and policy makers because of the potential threat to human health. Hence, an investigation of soil pollution is crucial to urban environmental assessment and management. Objective. To determine the spatial distribution and health risk assessment of seven heavy metals (cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn)) around Ijebu-ode, southwest Nigeria. Methods. Surface soil samples were analyzed for Cd, Cr, Cu, Mn, Ni, Pb, and Zn levels using standard procedures. Geographic information system (GIS) data, pollution indices (enrichment factor, geo-accumulation index), and the health risk assessment model, respectively, were used to analyze the spatial distribution, pollution level, and potential health risk of heavy metals. Results. Low pH was observed in the urban soils. The average concentrations of the seven heavy metals investigated were in order of Zn > Pb > Mn > Cu > Cd > Ni > Cr. There was high spatial variation in the distribution patterns of the heavy metals. The cancer risks for Cu, Mn, Pb, and Zn for children (1.50 × 10 −3 – 2.71 × 10 −2 ) and Mn, Pb, and Zn for adults (7.89 × 10 −4 – 2.97 × 10 −3 ) were higher than the acceptable range of 1 × 10 −6 - 1 × 10 −4 . Conclusions. Anthropogenic activities from different urban land uses contribute to the pollution levels and spatial distribution of heavy metals in soils. Increasing pollution of urban soil may contribute to the occurrence of some health risk for residents in the study area. Competing Interests. The authors declare no competing financial interests.

Background.Polycyclic aromatic hydrocarbons (PAHs) are common pollutants in water and have been reported to cause severe health effects in humans as well as the ecosystem.Objectives.This study examined the concentrations of polycyclic aromatic hydrocarbons and estimated the human health risk from water samples around Atlas Cove jetty, Lagos, Nigeria.Methods.Physical and chemical parameters and PAHs were determined in Atlas Cove jetty water using standard methods from June to August 2016 at five different points of activity. Chronic daily intake through ingestion, exposure dose via dermal absorption and carcinogenic risks were calculated for children and adults.Results.Electrical conductivity values ranged from 23,600±57.74 - 30,000±57.74 μS/cm. Dissolved oxygen ranged from 6.27±0.46 - 9.60±0.00 mg/L. Biochemical oxygen demand levels ranged from 2.93±0.61 - 7.33±0.23 mg/L and total dissolved solid ranged from 17,500±57.74 - 20,000±57.74 mg/L for the water samples, which was higher than permissible limits. The values obtained for pH, chemical oxygen demand, nitrate, sulphate and phosphate for the water samples were within World Health Organization (WHO) limits except for pH at point 2 (3.18±0.02). A total of eleven PAH congeners were detected in the water samples. The concentrations of total PAHs observed in water samples ranged from 46 - 507 μg/L. Low molecular weight PAHs were more dominant in all samples. It was observed that 2–3 ring PAHs accounted for 63.64% of PAHs, 4-rings PAHs accounted for 27.27% of PAHs, and 5–6 ring PAHs accounted for 9.09% of PAHs.Conclusions.Carcinogenic risks calculated for both adults and children were higher than the United States Environmental Protection Agency (USEPA) acceptable cancer risk, and much higher for children, which suggests that children could be prone to cancer through ingestion. Fauna and flora around the Atlas Cove jetty may be at risk due to water pollution.Competing Interests.The authors declare no competing financial interests.

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