Happy February, everyone! In this final instalment of ‘Trends from the WAY past’, I will be talking about the use of Mercury in common consumer products. The part of the video that discusses this is from 4:46 to 5:28. Once again, you don’t have to watch the video to read this post!
Are you familiar with the “Hatter” character in in Lewis Carroll’s 1865 book Alice’s Adventures in Wonderland? He is often referred to as the Mad Hatter. Yet, this term was never used by Carroll. The phrase “mad as a hatter” pre-dates Carroll’s works and has roots in reality. The phrase might actually be a result of mercury poisoning and was used to describe industrial hat-makers in the mid-1800s.
Hats were a major fashion trend and they were mainly felted and made out of animal fur. Felt is a textile made by compressing, rather than weaving, fibers together. To do this, the manufacturing of felted fur hats involved a process called “carroting” (Wajda, 2020). The carroting process employed the use of mercury nitrate, hence exposing hatters to high levels of mercury on a daily. This exposure did not only come from the carroting process, but also as vapors and dust wafting through the factory. Here, the contamination of the air with mercury deposits caused prolonged and extreme exposure to these hatters, causing them to contract mercury poisoning (Wajda, 2020). Exposure to mercury in any form is generally harmful and prolonged exposure or exposure in large amounts is especially so (Environmental Protection Agency, n.d.). Consequently, these hatters suffered from what is known as “Mad-Hatter Disease” and is marked by symptoms of prolonged exposure to mercury. Symptoms include tremors, muscle atrophy, poor mental function and changes to memory and personality as a result of prolonged exposure.
While the use of mercury to manufacture hats may not really be a thing now, we are still vulnerable to mercury poisoning. The hatters contracted mercury poisoning after being exposed to mercury nitrate, an inorganic form of mercury (Nunez, 2021). However, even if we do not come into direct contact with mercury, we are still vulnerable to mercury poisoning through organic forms of mercury, specifically, methylmercury. This can come from exposure to organic mercury by eating fish and shellfish containing methylmercury (Nunez, 2021).
Methylmercury is a type of Persistent, Bioaccumulative and Toxic (PBT) substance (Hill, 2010). This means that it (1) stays in the environment for long periods of time, (2) accumulates in organisms and (3) is harmful. Furthermore, methylmercury has the ability to biomagnify on top of bioaccumulating, meaning that it increases in concentration as it goes up the trophic levels (Gochfeld, 2003). There have been many epidemics of methylmercury poisoning throughout history, including the infamous Minamata incident which occured in 1956 leading to what is now known as Minamata Disease. Symptoms of Minamata Disease are similar to that of the Mad-Hatter Disease; what made the Minamata Disease especially damaging was its ability to be transferred via the placenta during pregnancy, resulting in many birth defects (Hill, 2010). Similar epidemics have occured in Niigata, Japan (1964) and Ontario, Canada (1970). The commonality between these epidemics is that this exposure to methylmercury is a result of chemical dumping by factories into water bodies. This large scale pollution has long lasting impacts due to the persistent nature of methylmercury.
Although there have been efforts to minimise such epidemics from happening, namely, the Minamata Convention on Mercury, we are not free from the risk of mercury poisoning. On top of the persistent nature of methylmercury, its ability to bioaccumulate and biomagnify means that as long as some form of it exists in the environment, the risk will never disappear.
Environmental Protection Agency (n.d.). Basic Information about Mercury. United States Environmental Protection Agency. Available from: https://www.epa.gov/mercury/basic-information-about-mercury#overview.
Gochfeld, M. (2003). Cases of mercury exposure, bioavailability, and absorption, Ecotoxicology and Environmental Safety, (56)1, 174-179. https://doi.org/10.1016/S0147-6513(03)00060-5.
Hill MK. (2010). Understanding Environmental Pollution [Internet]. 3rd ed. Cambridge: Cambridge University Press. Chapter 15, Metals. Available from: https://doi.org/10.1017/CBO9780511840654.016.
Nunez, K. (2021). What Is Mad Hatter Disease (Erethism)? Healthline. Retrieved from https://www.healthline.com/health/mad-hatter-disease.
Wajda, S. T. (2020). Ending the Danbury Shakes: A Story of Workers’ Rights and Corporate Responsibility. Connecticut History. Retrieved from https://connecticuthistory.org/ending-the-danbury-shakes-a-story-of-workers-rights-and-corporate-responsibility/.