Irrigation of agricultural lands
with treated and untreated sewage
wastewater led to the accumulation of heavy metals in the soil,
vegetables, cereals and milk samples.
Variations in the heavy metal
concentrations between the test vegetables/cereal crops reflect the
differences in uptake capabilities and their further translocation to
the edible portion of the plants. Cadmium, Pb and Ni concentrations
were above the national and various international permissible
limits in all the vegetables and cereal crops. The metal
pollution index and health risk index of heavy metals also suggest
that Cd, Pb and Ni contamination in most of the test plants had potential
for human health risk due to consumption of plants grown
at waste water irrigated site. Milk is found to be least contaminated
by heavy metals as its metal pollution index and health risk
index were lower compared to other foodstuffs. The health risk index
of cereals was higher than vegetables due to higher proportion
of cereals in the diet. Consumption of foodstuff with elevated levels
of heavy metals may lead to high level of accumulation in the body
causing related health disorders. The study suggests that even
though there are low concentrations of heavy metals in irrigation
water, its long term use caused heavy metal contamination leading
to health risk of consumers. Thus urgent attention is needed to
3devise and implement appropriate means of monitoring and regulating
industrial and domestic effluent, and providing appropriate
advice and support for the safe and productive use of wastewater
for irrigation.