Health Risk Assessment Levels of Selected Heavy Metals on Solanum Nigrum, Soils and Water Collected Along River Moiben, Uasin-Gishu County, Kenya

Abstract

The study investigated heavy metals’ levels in soil, Solanum nigrum and irrigation water from intense Moiben irrigated farms located in Meibeki Karuna, Uasin Gishu County. Purposive sampling was used to identify farms where there is an intense irrigated agricultural practice. Irrigation water, soil, and Solanum nigrum were randomly sampled, digested, and analyzed for heavy metals with the use of ICP-OES. SPSS Version 21 was used to analyse data statistically and means, Pearson Correlation coefficient, One-Way ANOVA and transfer factor were calculated. The heavy metals were compared from different sites. The soil mean concentration for Zn, Fe, Pb, Mg, Cr, Cu and Cd ranged between 46.90-0.18, 352–181, 10.75-9.91, 1.52-1.34, 10.14 - 9.67, 12.85 - 12.03 and 0.72 - 0.53 mg/kg correspondingly. Irrigation mean water concentration for Zn, Fe, Pb, Mg, Cr, Cu and Cd ranged between 0.071-0.054, 0.81- 0.669, 0.05-0.00, 0.05 – 0.045, 0.055-0.015, 0.27-0.197 and 0.005-0.001 mg/l respectively. Solanum nigrum mean concentration for Zn, Fe, Pb, Mg, Cr, Cu and Cd ranged between 0.001209 - 0.000592, 0.004003 - 0.002627, 0.000329 - 0.000079, 0.000837– 0.000565, 0.000104-0.000089, 0.000292-0.000204 and 0.000329-0.000004 mg/kg, respectively. One-way ANOVA indicated spatial significantly different in soil, water, and Solanum nigrum. The metal levels in soil were below WHO/FAO standards except Fe and Pb in irrigation water. Levels of Fe as well as Pb in Solanum nigrum were within WHO/FAO standards. Solanum nigrum are safe for consumption nevertheless continuous surveillance of heavy metals in soil, vegetables and irrigation water is vital preventive strategy to avoid accrual of heavy metals in the food chain.