There has been increased concern on many levels focused on the environmental and occupational exposure of heavy metals and their impact on disease, specifically the carcinogenic potential inducing cancer in humans. Because the impact of heavy metals on human health continues to be a major health concern, research continues to improve our understanding of the carcinogenic potential of these substances. Of particular concern have been human exposure to aluminum, arsenic, beryllium, cadmium, lead, mercury, nickel, and radium and their carcinogenic potential whether contact is via environmental or occupational exposure. This updated review focuses on the carcinogenic mechanisms heavy metals use to induce malignant transformation of cells as well as addressing the overall environmental and occupational hazards of heavy metal exposure.