Assessment of Potential Human Health Risk of Heavy Metals in Waterleaf (Talinum triangulare) Sold in Major Markets in Calabar, Nigeria

Sequel to the high rate at which waterleaf (Talinum triangulare) is consumed in Southern Nigeria and the excellent phytoextraction and bioaccumulation potentials of the plant, an assessment of the safety status and potential human health risk of Lead (Pb), Calcium (Cd), Chromium (Cd) and Nickel (Ni) through consumption of waterleaf sold in major markets in Calabar, Nigeria was carried out between February and April, 2021. A total of 36 composite samples obtained from 180 waterleaf vendors was used for the study. Heavy metals concentrations were determined using Atomic Absorption Spectrophotometer (Shimadzu, Model AA-6800, Japan) after wet digestion. The concentration (Mg Kg-1) ranged from 0.26-0.59 for lead, 0.04-0.42 for cadmium, 0.35-1.02) and 1.35-4.32 for nickel.  The mean metals content of edible tissues (leaves and tender stem) of waterleaf were found to be above FAO/WHO permissible limits and the EU maximum Levels for the metals in leafy vegetable except for chromium. The Estimated Daily Intake of the metals were above their respective Recommended Daily Intake and Upper Tolerable Daily Intake except for nickel. The average Target Hazard Quotients were greater than 1.00 except for chromium. The Hazard Index for the respective markets were greater than unity. The study concludes that Talinum triangulare purchased from the markets under study is not safe for human consumption as it poses significant toxicological risk with respect to lead, cadmium, and nickel and chromium intoxication.