Minamata disease was caused by mercury. Mercury is a toxic heavy metal that can have severe health effects on humans when ingested in high amounts. Minamata disease was first identified in the 1950s in Minamata, Japan, where a chemical company discharged wastewater contaminated with mercury into the ocean. Local residents who consumed contaminated seafood, such as fish and shellfish, developed neurological symptoms including numbness, tingling, muscle weakness, and loss of coordination. Over time, these symptoms progressed to convulsions, coma, and even death. Minamata disease highlighted the devastating consequences of mercury pollution and led to increased awareness of the dangers of mercury exposure. It also prompted stricter regulations on industrial waste disposal and the development of environmental policies to prevent similar incidents in the future.