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Background.Among soil contaminants, potentially toxic elements (PTE) are of major significance because they are ubiquitous, toxic and persistent. Chronic exposure of humans to these elements has been linked with developmental delay, cancer, atherosclerosis and kidney damage, stomach ailments, respiratory problems, heart disease and cancer.Objectives.The present study aims to investigate current PTE concentrations in urban soils of Lagos, an example of a rapidly urbanizing megacity in a developing country. The variation in PTE (chromium (Cr), copper (Cu), iron (Fe), magnesium (Mn), nickel (Ni), lead (Pb) and zinc (Zn)) levels across different land use types was examined. Information from this study will be useful in the ranking of contaminated sites, environmental quality management, guidance for remediation, redevelopment of contaminated sites and will provide crucial information for general urban planning decisions.Methods.Five areas spread across four local government areas were selected, representing different socio-economic areas of Lagos (Victoria Island, Lagos mainland, Ikeja, Ifako-Ijaiye and Makoko). Sampling locations within the study areas were comprised of school playgrounds, roadsides, ornamental gardens, open spaces, train stations, industrial estates and dump sites. A total of 126 samples were collected.Results.The overall mean levels of PTE concentrations in this study were comparable to those found in large European cities where main pollution sources include traffic and current or former heavy manufacturing industries.Conclusions.Regulation and legislation on environmental issues, including effective solid waste management strategies and enforcement of emission standards should be emphasized in order to reduce the impact of PTE pollution on the inhabitants of urban areas in developing countries.Competing Interests.The authors declare no competing financial interests

The ability of domestic cooking gas to induce hepatotoxicity and clastogenicity in mice was studied. The mice were exposed to domestic gas for twenty-one days at doses of 100 mg/kg, 200 mg/kg and 300 mg/kg respectively. The positive control group of mice were given sodium arsenite intraperitoneously at a dose of 2.5mg/kg body weight. While the negative control group had only distilled water, sodium arsenite significantly (p < 0.05) induced the formation of micronucleated polychromatic erythrocytes (mPCEs), serum and liver gamma glutamyl transferase (γGT) and alkaline phosphatase (AP) activities respectively as compared with the observations made in the negative control group. Similarly, the domestic gas significantly (p<0.05) induced mPCEs formation, serum and liver, γGT and AP activities. The degree of induction was in the order of 100 mg/kg < 200 mg/kg < 300 mg/kg. However, when compared with the positive control group, the domestic cooking gas at the tested doses was not as potent as sodium arsenite in its ability to induce enzyme activity and mPCEs formation. Limited histopathological analysis of liver samples from treated and untreated mice showed distended blood vessels, necrosis and hepatocellular degeneration in the groups treated with high doses of domestic gas or sodium arsenite as compared with the untreated group. Our findings suggest that the domestic cooking gas has some degree of clastogenic and hepatotoxic activities in mice. Health risks may therefore be associated with long-term occupational and / or domestic exposure in humans.

Exposure to hexavalent chromate compounds such as other human carcinogens is unavoidable in the developing countries of the world. Research efforts are being directed toward minimizing exposure to them, intercepting their activity in vivo, and/or prophylaxis. The present study therefore evaluates the effect of methanol extract of the leafy vegetable, Corchorus olitorius (MECO), against potassium dichromate (K2Cr2O7)-induced toxicities. Negative control animals were fed distilled water, while the positive control rats received 12 mg/kg body weight K2Cr2O7 once a week for 6 weeks. Test rats were exposed daily to 25, 50, and 100 mg/kg body weight MECO alone for 6 weeks and 12 mg/kg body weight of K2Cr2O7 once a week for 6 weeks before sacrifice. The frequency of micronucleated polychromatic erythrocytes (mPCEs) was monitored in bone marrow cells, while induction of aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine levels, and hematological parameters were assessed in the plasma. The phytochemical analysis of MECO was also carried out. K2Cr2O7 significantly (P < .05) increased the levels of mPCEs, AST, ALT, creatinine, total white blood cells, and lymphocytes compared with the control. The percentage pack cell volume and neutrophils were, however, reduced. In contrast, MECO at different doses restored the markers toward the levels of the negative control. MECO is rich in flavonoids, saponins, anthraquinones, terpenoids, and phenols, and they might be responsible for the protective effect observed in this study. Our results suggest that MECO has a promising potential in the treatment/management of chromate-induced toxicities.

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