Mercury and Madness: The Case of the Mad Hatter

Amanda Buerger

There is often a historical truth behind fictional characters, no matter how absurd it may seem. I was 22 years old, in my first class as a PhD student, when I learned that there was something more to an iconic character from my childhood than I realized. Alice in Wonderland’s Mad Hatter may not have been just this fun, crazy, unpredictable character - he was possibly inspired by real-life hat makers suffering from chronic mercury poisoning.

Often cited as a classic example in occupational toxicology, Mad Hatter Disease (also known as Erethism) is a neurological condition resulting from daily exposure to mercury fumes. Mercury was used to help hatters manipulate felt into hats. However prolonged (chronic) inhalation exposure to mercury often led to hatters experiencing tremors and various psychological symptoms, including depression, irritability, and even hallucinations. Various reports of this disease and its relationship to hat-making emerged as early as the 1800s; in fact, a cohort of New Jersey hat makers were experiencing these symptoms in 1860, just 5 years prior to the publication of Alice in Wonderland by Lewis Carroll.

Long after the hazards of occupational mercury exposure were first observed, the United States outlawed the use of mercury in the felt industry in 1941. This was not the only time the United States government has acted to protect workers from occupational hazards; for instance, in 1989 the Environmental Protection Agency banned the use of asbestos in building materials after evidence emerged that asbestos exposure results in chronic respiratory problems. As technology continues to advance, we must work to proactively protect workers before they become ill. While the Mad Hatter is an iconic and beloved character, the reality behind his origin is heartbreaking, and is a powerful reminder of the importance of occupational safety procedures and regulations.