Health Risks for a Rural Community in Bokkos, Plateau State, Nigeria, Exposed to Potentially Toxic Elements from an Abandoned Tin Mine.

The past mining activities in Bokkos Local Government Area (LGA) were performed in an uncontrolled way and gave rise to many abandoned ponds now serving as domestic and irrigation water sources. Past research focused mainly on the environmental impact, and we show for the first time what the human health risk through consumption of contaminated food crops is in these communities. This study was designed to determine the level of Potentially Toxic Elements (PTEs) contamination in pond water, soil, and food crops and assess the health risk of inhabitants in the abandoned tin mining community in Bokkos LGA. Samples of the mining pond water, soil, and selected food crops from farms irrigated with the pond water: bitter leaf (Vernonia amygdalina), pepper (Piper nigrum), okra (Albelmoschus esculentus), maize (Zea mays), sweet potato (Ipomoea batatas), and Irish potato (Solanum tuberosum) were analyzed for each of the eight PTEs (viz. Cu, Cr, Fe, Mn, Ni, Zn, Cd, and Pb) using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained showed that the levels of all the PTEs analyzed in the soil, pond water, and selected food crops except for Fe and Mn in soil and Cd in sweet potato were greater than their corresponding background area values (p < 0.05). Also, the mean concentrations of all the PTEs except for Cu in pond water were significantly (p < 0.05) higher than the WHO maximum permissible limit. With the exception of Fe, Ni, and Zn for pepper and okra, Cu and Fe for maize grains as well as Cu, Ni, and Zn for sweet and Irish potatoes and Fe and Cd for sweet potato, the mean concentrations of PTEs in the food crops were significantly higher than WHO maximum permissible limit. The EF values of Cd (0.39); Cu (3.59) and Ni (2.81); Cr (9.38) and Pb (17.84); and Mn (178.13) and Zn (83.22) classified the soil as minimally, moderately, significantly, and extremely highly enriched, respectively. The PI values of all the PTEs in the soil studied were all greater than 5, indicating that the soils were severely contaminated. There was evidence that food crops significantly bioaccumulated PTEs either as a result of contaminated soil and/or irrigation water. The bioaccumulation was not uniform and was dominated by transfer from the polluted irrigation water. The bitter leaf, okra, and to some extent maize had the highest transfer of PTEs, and Mn, Cu, and Zn had the highest bioaccumulation in the food crops investigated. The hazardous index (HI) for the eight PTEs through the consumption of food crops was 107 for children and 33 for adults which greatly exceeded the recommended limit of 1, thus indicating that possible health risks exist for both local children and adults. For every PTE, the values of HI for children are many-fold higher than those for adults, which is of particular concern due to the high HI values for Pb found for maize consumption, a typical staple food. The cancer risk values for Cr and Ni for all the food crops were within 10-3-10-1 which is several fold higher than the permissible limits (10-6 and < 10-4) indicating the high carcinogenic risk. It can be concluded based on the results and risk assessment provided by this study that human exposure to mining pond water and soil in farms around the mining pond through the food chain suggests the high vulnerability of the local community to PTE toxicity. Long-term preventive measures to safeguard the health of the residents need to be put in place.

Chloroform extract and acetyl-11-keto-beta-boswellic acid from Boswellia dalzielii stem bark induce apoptosis and cell cycle blockage in AW8507 cells.

BACKGROUND: Globally, head and neck cancer is the sixth most common cancer. Despite the advancement in treatment, drug resistance remains a major cause for setback. In an earlier work, the authors reported that Boswellia dalzielii (Hutch) stem bark exhibited dose-dependent cytotoxicity in head and neck cancer cells, AW8507. Therefore, the cell death induction effect of Boswellia dalzielii stem bark chloroform extract in head and neck cancer cell line, AW8507, and its derived constituent on cell cycle and apoptosis proteins was further investigated. METHODS: The cell death induction activity of the Boswellia dalzielii stem bark chloroform fraction (CLBD) in AW8507 was determined using Annexin V-FITC/PI staining in flow cytometry. High-performance liquid chromatography-mass spectrometry was employed for compounds analysis of the CLBD, and reverse virtual screening was used to identify the mechanism of action of the compound, acetyl-11-keto-beta-boswellic acid, that was elucidated in the Boswellia dalzielii chloroform fraction. RESULTS: The data obtained showed that Boswellia dalzielii stem bark Chloroform extract increased the percentage of cells presenting for early apoptosis from 4.14 to 10.10% in AW8507 cells. High-performance liquid chromatography-mass spectrometry analysis of the chloroform fraction identified acetyl-11-keto-beta-boswellic acid. Reverse virtual screening on selected proteins showed that acetyl-11-keto-beta-boswellic acid is a multi-protein target compound. It binds preferably to phosphorylated-cyclin dependent kinase 1 (p-CDK1) (binding score = - 9.2 kcal/mol), blocking the activation of cyclin B-CDK1 needed for cell cycle progression at G2/M phase of the cell cycle. Acetyl-11-keto-beta-boswellic acid also binds more tightly with αß tubulin (binding score = 8.9 kcal/mol) than with the standard drug, docetaxel (binding score = 8.3 kcal/mol). CONCLUSIONS: The results obtained confirmed the culpability of Boswellia dalzielii-derived acetyl-11-keto-beta-boswellic acid in the obstruction of the cell cycle progression in head and neck cancer cell line, AW8507; and the induction of apoptosis earlier reported for Boswellia dalzielii (Hutch) stem bark. Additional in vitro and/or in vivo studies would be required to validate in silico observations.

Benzo[a]pyrene and Benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide induced locomotor and reproductive senescence and altered biochemical parameters of oxidative damage in Canton-S Drosophila melanogaster.

Benzo[a]pyrene (B[a]P) is a polycyclic aromatic hydrocarbon (PAH) commonly found in cigarette smoke, automobile exhaust fumes, grilled meat, and smoked food among others. Exposure to B[a]P is associated with a range of toxic effects including developmental, neurological, oxidative, inflammatory, mutagenic, carcinogenic and mortal. Efficient and more affordable experimental models like Drosophila melanogaster could provide more insight into the mechanism of PAH toxicity and help develop new strategies for prevention, diagnosis and treatment of PAH-related conditions. In this study, we examined the induction of some biochemical changes along with mortality and functional senescence by B[a]P and its metabolite, benzo[a]pyrene- 7,8-dihydrodiol-910-epoxide (BPDE) in the Canton-S strain of Drosophila melanogaster, with the aim to establish an alternative assay medium for B[a]P toxicity in flies. Flies were exposed to 2-200 µM of B[a]P and 1-10 µM of BPDE through diet for a seven-day survival assay followed by a four-day treatment to determine the effects of the compounds on negative geotaxis, fecundity and some biochemical parameters of oxidative damage. BPDE significantly reduced the survival rate of flies along the 7 days of exposure whereas B[a]P did not cause any significant change in the survival rate of flies. B[a]P and BPDE significantly reduced the climbing ability of flies after 4 days of exposure. Rate of emergence of flies significantly reduced at 10-200 µM of B[a]P and 5-10 µM of BPDE. Both compounds caused various levels of alterations in the values of reduced glutathione (GSH), total thiol (T-SH), glutathione-S-transferase (GST), catalase (CAT), hydrogen peroxide (H2O2), nitric oxide (NO) and acetylcholinesterase (AChE) of the flies. The compounds also exhibited high binding affinities and molecular interactions with the active site amino acid residues of Drosophila GST and the inhibitor binding site of Drosophila AChE in an in silico molecular docking analysis, with BPDE forming stable hydrogen bonds with AChE. Hence, the Canton-S strain of Drosophila melanogaster could offer a simple and affordable assay medium to study B[a]P toxicity.