Mercury is notorious, dangerous and extremely toxic
The metal was at the heart of one of the worst industrial disasters the world has ever seen, a tragedy that spanned almost the entire twentieth-century.
In 1908, chemical group Chisso Corporation opened a plant in Minamata, Japan. The company was a heavy user of mercury-based catalysts and contaminated waste products were released into Minamata Bay for decades. By the middle of the century, doctors began seeing patients with disturbing symptoms, which ultimately prompted the discovery of Minamata disease, a severe central nervous system disorder caused by poisoning from mercury found in shellfish.
The Japanese government began to clean up Minamata Bay in the late 1970s but the process took 20 years, cost over US$350 million and destroyed thousands of lives. As a result of the calamitous events in that area, Japan was the first country to ban the use of mercury for any industrial application.
Mercury has been linked to several other industrial accidents too. Yet annual consumption of the metal still amounts to around 4,000 tonnes and, even though there have been significant improvements in the way it is handled, hundreds of tonnes are still released into the environment every year.
Mercury has a number of applications so its continued use is perhaps understandable. But the memory of Minamata casts a long shadow, spurring the United Nations Environment Programme to establish the Minamata Convention on Mercury in August 2017.
Signed by more than 150 countries including the US, Russia, all 27 EU states, and China, the Convention is designed to protect human health and the environment from anthropogenic emissions of mercury and mercury compounds, across a range of products, processes and industries.
One industry that is particularly affected by this convention is the polyvinyl chloride (PVC) industry. The Chinese PVC industry is effectively the world’s largest consumer of mercury, responsible for roughly a quarter of global consumption. The manufacturing process uses a catalyst containing high concentrations of mercury in the production of vinyl chloride monomer (VCM), which is the intermediate chemical to PVC. A significant proportion of the mercury on the catalyst can be lost through evaporation, either during VCM production or during reprocessing of the used catalyst. These losses can result in mercury emissions to both air and water.
Annual consumption of mercury amounts to around 4,000 tonnes and hundreds of tonnes are still released into the environment every year.