Heavy metal toxicity occurs when harmful levels of metals like lead, mercury, cadmium, or arsenic accumulate in the body. These metals can enter the body through contaminated food, water, or air, and they can disrupt normal biological functions. Symptoms may include fatigue, headaches, and gastrointestinal issues, depending on the type and amount of metal exposure. Long-term exposure to heavy metals can lead to serious health problems, including damage to the nervous system, kidneys, and liver. Children are particularly vulnerable, as their developing bodies can be more affected by these toxins. Prevention involves reducing exposure and monitoring environmental sources of heavy metals.