Human health risk assessment of heavy metal concentration in surface water of Sosian river, Eldoret town, Uasin-Gishu County Kenya.

Heavy metal pollution in surface waters has become a major worldwide issue as people tend to settle where there is readily available source of water like a river. This research evaluates the causes, concentration and associated health risks of heavy metals in River Sosiani as it passes through the town of Eldoret. Seven water samples were collected and analysed for zinc (Zn), copper (Cu) and lead (Pb. The results disclosed that Pb concentrations were estimated to be in the range of 0.06 mg/l to 0.23 mg/l, higher than the permitted limit by WHO of 0.01 mg/l. Cu and Zn concentration levels were below the permissible limits. The chronic daily intake (CDI) indicated that total hazard quotient of non-cancer risk of Pb was above one and the total HI values for children were greatly elevated compared to those of adults in the studied area. This showed a high risk in exposure to Pb. Health human risk was assessed and the incremental life cancer risk (ILCR) values of Pb for children and adults in all sites were found to be negligible with values below 10. However, there is higher cancer and non-cancer risk for children than adults as far as lead metal is concerned. Therefore, measures should be taken in accordance with the standards to prevent potential risk of the river pollution.•Human activities make a significant contribution to heavy metal pollution to surface waters which is a threat to humans.•Water from Sosiani River is not safe for use domestically as far as lead metal levels are concerned.•The results of this study can be used by decision makers to develop measures which can improve the quality of water in the river catchment.