CdCl2 has zero-order kinetic cellular influx and induces cytotoxicity and genotoxicity at low concentrations in human leukocytes in vitro

Cadmium (Cd2+) is a nonessential heavy metal that possesses a high capacity of bioaccumulation and exhibits toxic characteristics even at low concentrations. This study evaluated the genotoxicity and cytotoxicity in human leukocytes in vitro after exposure to a lower range of Cd2+concentration (1-25 μg/mL) using an unprecedented strategy by correlating between intracellular Cd2+ levels after exposure and cellular damage. Results demonstrated that Cd2+exposure from 5 to 25 μg/mL significantly increased the unviability of leukocytes, as well as the DNA damage, which was dose-dependent. The intracellular Cd2+ levels in leukocytes ranged from 9.85 to 94.38 pg/cell, and cytotoxicity and genotoxicity were induced at a concentration of 24.22 pg/cell. The relationship between exposure concentration and intracellular Cd2+ levels suggests that its influx occurs in human leukocytes under zeroorder kinetics.