The Mad Hatter

We all remember the Mad Hatter, the character in Alice in Wonderland. Alice meets the Hatter having tea with the March hare and the Dormouse. He acts erratically, asking nonsense riddles, reciting ridiculous poetry, switching places at the table, biting his teacup, and making nonsensical statements, like “You’ve lost your muchness: “You’re not the same as you were before. You used to be much more… muchier… you’ve lost your muchness”.

The term “mad as a hatter” was a popular term many years before Lewis Carroll wrote Alice’s Adventures in Wonderland in 1865. It all started in France in the 1600s, when felt hats became popular. The Huguenots developed a process to stabilize wool in a process called felting, during which hair was cut from a pelt of an animal such as a rabbit, matted together, treated with mercuric nitrate, and shaped into cones. This process, a trade secret in France, spread, as Huguenots moved to England in the 1700s. The hatters often worked in confined areas with poor ventilation, and the job quickly became known as a hazardous one. What they didn’t know then was that, as the treated felts were repeatedly boiled, dried, and shaped, volatile free mercury was released in vapor. Though no one knew why, everyone in the industry began to understand that hatters developed problems, including mental confusion, emotional disturbances, muscular weakness, tremors, and an almost pathological shyness. As the poisoning worsened, memory loss, red ears and fingers, sweating, tooth loss, and marked irritability ensued.

For over one hundred years, felt hats were popular, and people generally knew that hatters would get sick at work. It was accepted as an unpleasant fact, and sometime during the early 1800s, the term “mad as a hatter” became common.

How did it ever get better? Slowly, it appears.

• In Europe and England, progress took over 40 years. 1861- Dr Kussmaul, a German physician, wrote the definitive treatise on mercury poisoning and its symptoms, but only mentioned hatters in passing.
• 1867- British toxicologist Taylor reported mercury poisoning in a hatmaker. Only a few years later in 1869, the French Academy of Medicine publicized the hazards to hatmakers and soon, other alternatives for felt making were developed.
• 1898- In France and England, laws were passed to protect hatters, and by 1900, mercury poisoning among hatmakers had become rare in Europe.
• But what about the US? A detailed description of occupational mercury poisoning among hatters in New Jersey (where there was a thriving hat industry) was published in 1860. Twenty years later, a hydrochloride-based process for felting was patented, but was ignored. Over the next sixty long years, there continued to be multiple medical articles, occupational inspections and Bureau of Labor reports that showed serious illnesses from chronic mercury poisoning, yet nothing was done. Hatters all knew illness was common in the industry, but management professed to be unaware. Why? The problem was totally overshadowed by the elephant in the room, tuberculosis. It was the number one killer in America in the late 19^th and early 20^th century, and efforts to improve workers’ conditions because of TB eclipsed everything else. In fact, American hatmakers continued to use mercury until 1941. They changed to hydrogen peroxide then, only because mercury was needed for the war effort.

But back to Lewis Carroll and Alice. Hat making was the predominant trade in Stockport, where Carroll grew up. Popular novels of the period sometimes included stories of workers in the textile industry who developed neurologic illnesses. We know Carroll read many of these books. Often, such workers were sent to lunatic asylums. It just so happened that Carroll’s uncle was a Lunacy Commissioner, supervising these asylums. Carroll was familiar with the conditions of asylums and had visited at least one. So, he would have known all about “mad hatters” of the day.

And thus, an enduring hat fashion led to chronic poisoning, and a common term for workers poisoned by mercury made its way into children’s literature!

A Modern-Day Addendum:

By the way, what about that good old thermometer you have at home? If it’s glass, and not digital, does it have mercury? The good news is that since 2001, mercury thermometers have been banned for medical and household use. Your glass thermometer probably has red colored alcohol in it. And if you do happen to have an old mercury one and break it, call Poison Control; they will tell you exactly how to safely clean it up. Whatever you do, don’t vacuum it up; that will heat up the mercury and cause it to give off toxic vapors, which is where the problem lies. If your toddler eats the mercury, call your pediatrician. However, I can reassure you that liquid mercury is poorly absorbed in the stomach, and there is not likely to be any harm.

So, the lesson is, you can feel good about using thermometers, and wearing felt hats now.