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.
