The cause of "Mad Hatters' Disease" was traced to:

The designation of "Mad Hatters' Disease" is historically tied to the neurological effects caused by mercury exposure. In the 18th and 19th centuries, hatmakers often used mercuric nitrate in the process of curing fur to create felt hats. This prolonged exposure to mercury vapors led to mercury poisoning, which manifested in various neurological symptoms, including tremors, mood changes, irritability, and cognitive decline. The term "mad hatter" is derived from these dramatic effects, which were observed in the individuals working with mercury in the hat-making industry. Therefore, the correct identification of the cause of "Mad Hatters' Disease" as mercury highlights the significant health hazards linked to heavy metal exposure in occupational settings. Understanding this historical context is essential for grasping the importance of proper safety regulations and monitoring in environments where toxic substances are present.