Unrevealing arsenic and lead toxicity and antioxidant response in spinach: a human health perspective.

Arsenic (As) and lead (Pb) are highly toxic and carcinogenic metal(loid)s. The present study evaluated the human exposure risk via estimating As and Pb uptake and physiological/biochemical modifications inside spinach plant grown under metal(loid)-contaminated growth medium. Plants were treated with three levels of each metal(loid) (0, 25 and 125 µM) for four weeks. The spinach plants accumulated high concentration of metal(loid)s in roots (0-18.9 ug g Pb and 0.2-22.7 ug g As) and less were translocated towards shoot (0-0.3 ug g Pb and 0.2-8.8 ug g As). Metal(loid) accumulation in plants decreased plant biomass and pigment contents and provoked oxidative stress by increased hydrogen peroxide (HO) production in roots up to 65% and 22%, respectively, for As and Pb. The production of HO in leaves was decreased up to 59% and 45%, respectively, for As and Pb than control. Moreover, the antioxidant system (superoxide, catalase, guaiacol peroxidase, ascorbate peroxidase) gets activated under metal(loid) stress. The exposure assessment indices revealed high carcinogenic (CR > 10) and non-carcinogenic (HQ > 1) risks owing to the consumption of As- and Pb-contaminated spinach leaves. Results revealed As is being more toxic to plants and humans than Pb. These findings suggest possible alarming consequences of As and Pb to spinach and their assimilation within the edible tissues.