Heavy metals are a group of metallic elements that have a high atomic weight and density, and are often toxic at low concentrations. Common heavy metals include lead, mercury, cadmium, arsenic, and chromium. These metals can accumulate in living organisms and the environment, leading to various health issues, including neurological damage, kidney problems, and developmental disorders. Heavy metals can enter ecosystems through industrial activities, mining, waste disposal, and agricultural practices, posing significant risks to human health and environmental sustainability.