Elements denser than water are known as heavy metals, and they are a major global danger to the environment and human health. The ubiquity of each metal in diverse environmental matrices is highlighted by its existence in both natural and industrial sources. Human exposure pathways include everything from food consumption to work environments, and they all contribute to a variety of health effects and organ system damage. Notably, longterm exposure to these metals is associated with increased cancer incidence rates, which can impact the neurological systems, lungs, kidneys, skin, liver, and other organs. The molecular details of the toxicity and carcinogenicity of individual metals reveal a variety of processes, such as DNA damage, oxidative stress induction, disruption of cellular respiration, disruption of signal transduction pathways, and changes in gene expression. Priority heavy metals (cadmium, chromium, arsenic, lead, and mercury) have distinct toxicological profiles, but this review emphasizes the urgent need for comprehensive strategies to reduce environmental contamination and human exposure. It does this by highlighting the complex interactions between environmental events, anthropological sources, and the molecular basis of heavy metal-induced carcinogenicity and toxicity. Keywords: Environmental Contamination, Heavy Metals, Environmental Health Impacts, Molecular Mechanisms, Metal Toxicity