Abstract:
Urban vegetable farming is popular in Tanzania and other countries partly due to readily
available market and reliable transport to reach consumers. River banks are usually used to
grow such vegetables due to closer proximity to water and whenever necessary use such water
for irrigation. However in urban settings river water pollution by toxic heavy metals and
subsequent accumulation of the metals in nearby grown vegetables has been reported as
among major sources of exposure to humans and animals. Heavy metals, including lead (Pb)
have many health effects to human and animals ranging from acute to chronic illnesses. This
study was conducted to assess the occurrence of lead in Morogoro river and in edible
vegetables (Amaranthus retroflexus) grown along the river bank. Water and vegetable
samples collected during dry and rainy seasons were prepared and analysed for occurrence
and levels of lead using Atomic Absorption Spectrometry (AAS). It was found that
concentration of Lead in the water and vegetable samples were up to 0.95 mg/L, and 0.026
mg/Kg respectively. It was also found that 77% of the water samples and 28% of the
vegetable samples had lead levels above the WHO recommendations. The frequency and
levels of lead occurrence varied with topographical, diurnal and seasonal characteristics of
sample collection. The results of this study raise concerns on the use of water for human and
animal consumption from rivers which run across urban areas and call for further studies to
investigate for any health consequences to consumers.
