Human Health Risk Assessment Associated with Consumption of Vegetables Grown on Land Irrigated with Polluted Urban River Water in Jimma Town, South West Ethiopia

Abstract

Urban polluted river water used for irrigation can be contaminated by heavy metals and pathogenic microorganisms which contaminate soil and vegetables grown by it which brings health risk to consumers those consumed contaminated vegetables. The objective of this study was to assess human health risk associated with consumption of vegetables grown on land irrigated with polluted urban river water in Jimma town, south west of Ethiopia. The study was conducted in Jimma town from March to May 2018. The samples were collected during dry season for both heavy metal and microbial analysis from three sites (upper, middle and lower sites) and one control sample for each source from outside Awetu river catchment. The concentration of heavy metals was analyzed by atomic absorption spectrophotometer and microbial contaminants was analyzed following standard procedures. Health risks associated with these heavy metals were assessed based on total hazard quotients: that can be derived from concentrations of heavy metals in vegetables consumed in the area. The concentration of heavy metals in edible parts of vegetables increases in vegetables grown in downstream when compared with the upper stream metal concentration for both cadmium and lead. The mean metal concentrations for Pb were above the safe limits of world health organization’s standards, while the mean Cd concentration was below safe limits. Health risk for Cd and Pb possess no potential risk to the local inhabitants through consumption of contaminated vegetables grown in the area as the value for total hazard quotient was less than 1, but the long term accumulation of these metal gradually increase the concentration in the environment and along the food chain accumulates in the body and thus can cause serious health problems. The study on microbial contaminants of vegetable indicates that all the vegetable samples were contaminated and none of them met the world health organization maximum permissible level for raw eaten vegetable consumption. The contaminated river water used for irrigation contaminated the vegetable. Thus, detail risk assessment should be conducted from production to consumption in order to provide complete intervention in reducing microbial diseases from vegetables.