Heavy Metal contamination in vegetable grown with wastewater in peri urban areas of Multan City, Pakistan: A Health Risk Assessment

Abstract

A study conducted in Multan, Pakistan, evaluated the health risks posed by heavy metal contamination in commonly consumed vegetables cultivated using various water sources. A total of 100 vegetable samples, including 30 samples of Brassica, were analyzed for cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), and lead (Pb) using ICP-OES. Additionally, 30 soil samples and 30 water/wastewater samples were analyzed for the same metals.

The findings revealed that vegetables irrigated with wastewater had significantly higher levels of heavy metal accumulation compared to those grown using canal or tube well water. The accumulation factor, representing the concentration of metals in plants relative to the soil, ranged from 2.50 to 13.74 in wastewater-irrigated vegetables, compared to a much lower range of 0.34 to 0.57 for vegetables grown with clean water sources.

Moreover, the total target hazard quotient (TTHQ), which evaluates the combined health risks from exposure to multiple metals, was notably higher in wastewater-irrigated vegetables. These vegetables posed a "carcinogenic health risk" to the exposed population, whereas vegetables grown using canal or tube well water were considered "health risk-free."

Multivariate statistical analysis confirmed that wastewater irrigation is a significant contributor to heavy metal contamination in soil and vegetables. The study underscores the necessity of treating wastewater prior to its use in agriculture to minimize health risks associated with heavy metal exposure