Detection of human health risks resulting from contamination of borehole drinking water with harmful volatile organic chemicals and potentially toxic elements around petroleum products dispensing outlets.

Detection of human health risk caused by gasoline volatile organic chemicals and potentially toxic elements using an integrated approach to optimise data interpretation. The area is an urban centre with petroleum dispensing outlet and depending largely on borehole drinking water. Organic and toxic elements were analysed using gas chromatography and atomic absorption spectrophotometer, respectively. The study combined multivariate statistics and human health risk calculations. The water is moderately acidic causing low dispersion of toxic elements. Turbidity mean value of 15.64 NTU exceeded World Health Organization standard of 5NTU for potable water reflecting water pollution. Mean levels of benzene 2.20 mg/L and toluene 1.62 mg/L exceeded world standards for potable water. Benzene possesses higher daily intake levels in children than in adults through both ingestion and dermal contact. In children, benzene obtained hazard quotient ranging from 4.8 to 6.6 through dermal contact and 71.9-102.6 via ingestion pathway. Hazard risk of benzene ranged from 1.05 to 9.6 and 2.5-3.4 and toluene from 1.1-1.7 in children and adults. These values are greater than 1 reflecting non-carcinogenic risk. Cadmium, arsenic and antimony displayed non-carcinogenic risk in locations 2, 3, 4, 7, 9, 12, 14, 15 and 17. Carcinogenic risk of benzene and ethyl benzene in children via ingestion show that 1 in 0.0001 % and 1 in 0.01 % are susceptible to cancer in a lifetime of 70 years. Cadmium and arsenic has carcinogenic risk through ingestion pathway and dermal contact in children and adults. Incremental lifetime cancer risk of benzene, ethylbenzene, arsenic, lead and cadmium were above acceptable standard of 1.0E-06-1.0E-04 in children than adults through ingestion pathway than dermal contact. Buried petroleum storage tanks contributed to pollutants in the borehole water. Dissolution, dispersion and migration of benzene, toluene and ethyl benzene to boreholes adjacent to petroleum products outlets has harmful effects to water consumers. Integrating multivariate analysis, human health risks, odour hazard and risk index factor advances our understanding compared to previous works.