Mercury: The Poison Rebranded as Medicine, Fashion, and Profit for Centuries

In 1693, Isaac Newton spent months unable to sleep, eating poorly, and writing letters accusing friends of harming him. He had worked with alchemy for years, heating metals with mercury, lead, and arsenic. In 1979, two Royal Society papers examined samples of Newton’s hair and found very high mercury levels. The evidence does not prove that mercury caused his entire crisis, but it shows prolonged contact with a neurotoxic substance.

Almost two centuries later, European hatters inhaled mercury vapour in sealed workshops. Their hands shook, memory failed, and their personalities changed. The phrase “mad as a hatter” turned victims into a joke instead of naming an occupational disease. In 1956, people in Minamata, Japan, began to be recorded with a neurological disease caused by eating fish contaminated with methylmercury from the Chisso factory. The company denied the connection for years and used agreements that restricted victims before courts held it responsible.