Concentration and non-carcinogenic risk assessment of heavy metals in leafy vegetables among different farming practices

Accumulation of heavy metals in vegetables grown using different farming methods, particularly when these metals poses significant health risks. This study investigates the levels of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni) and antimony (Sb), in leafy vegetables (coriander, fenugreek, and mint) grown using three different farming methods, i.e. conventional, organic, and hydroponic farming methods. Non-carcinogenic health risks were assessed using the estimated metal daily intake (MDI) and target hazard quotient (HQ) for each metal. The cumulative non-carcinogenic hazard posed by exposure to these heavy metals was further evaluated by determining the health risk index (HI). The heavy metal concentrations in conventionally, organically and hydroponically grown vegetables ranged from 0.01 to 4.49 mg per kg, 0.01 to 1.95 mg per kg, and 0.01 to 3.56 mg per kg respectively, which revealed that leafy vegetables grown conventionally and hydroponically contain significantly higher concentrations of these heavy metals compared to those grown organically grown leafy vegetables. The HI value of coriander, fenugreek and mint leaves for all the studied metals range from 0.17 to 0.35 in organic, 0.94 to 1.96 in conventional and 0.73 to 1.49 in hydroponic leafy vegetables respectively, which suggested that the intake of conventionally and hydroponically grown can expose adults and children to adverse non-carcinogenic health effects. The results emphasise the importance of stringent monitoring of agricultural inputs and water quality across all farming methods to mitigate heavy metal contamination and ensure food safety.