 This article reviews the toxic effects of common heavy metals such as mercury, lead, chromium, cadmium, and arsenic on human health following exposure through water, air, and food. These metals disrupt cellular events including growth, proliferation, differentiation, damage repairing processes, and apoptosis. They generate reactive oxygen species, weaken the antioxidant defense, inactivate enzymes, and cause oxidative stress. Some heavy metals selectively bind to specific macromolecules, while others cause genomic instability and cancer. Despite current knowledge of their hazards, heavy metal poisoning remains a significant public health concern that requires preventive and effective treatment. This article was authored by Madi Balali Mood, Cobra Nasri, Zoya Targarabi, and others.