Relationship between Mercury and Human Beings
Ancient ~ Medieval
Mercury is rarely found as a single element in nature and instead in the form of red sulfide (=HgS: cinnabar) in mainly hydrothermal deposits in volcanic regions and hot-spring areas. When red cinnabar is heated in air, it changes into silver white mercury.
The relationship between mercury and human beings has quite a long history. The red paint seen in quite a number of excavated artifacts is mainly composed of mercury sulfide (cinnabar), which has been discovered in ancient graves in Egypt and remains of the Yin Dynasty in China. Mercury found favor as an ingredient in an elixir of life by a long line of emperors in China, including Shi Huangdi. In Japan too, mercury has been historically held in high esteem not only as a medicinal ingredient but also as a pigment in the Asuka Period.
In Japan cinnabar was also used on shrine gates and red-lacquered gates from the Yamato Court period. Among others, a rather famous historical use of mercury in the form of cinnabars is the gold plating used on the Great Buddha at Todai-ji Temple when it was constructed during the Nara Period. It is said that the plating was finished off by the copper and amalgam which was made from gold and mercury mixed at certain ratios before being applied to the surface of the Great Buddha and being externally heated to then evaporate off the mercury contained in the plating. The amount of mercury used in the casting process of the great statue of Buddha has been estimated to have exceeded two tons, and it is also said that a large number of people died during that construction because they had inhaled the toxic mercury gas that resulted from the process.
Mercury was considered more valuable than gold and silver in ancient Japan and indeed as a very precious metal, and so much that people said “the person who controls mercury also control the political power.” According to a story, Kukai (Kobo Daishi), who visited China during the Tang Dynasty period, learned how to identify veins of copper and mercury before returning to Japan, which supports the supposition that many mineral resource producing areas throughout Japan also corresponded with places that were famous for their association with Kukai.
Furthermore, Newton is also said to have seriously engaged in research on eternal youth and immortality via use of mercury.
Mercury has maintained a close relationship with our everyday lives and greatly contributed to the development of the global economy until restrictions on the use of mercury occurred due to tighter international regulations in the late 1900s.
Around the same time, the demerits of mercury were also highlighted, and which resulted in various regulations.
Merit/Demerit of mercury
Merits of Mercury
Representative uses of mercury in the world include:
- gold mining and refinement of gold amalgam;
- mercury cells;
- measurement and control equipment (clinical thermometers, blood pressure gauges, etc.);
- chemicals (antiseptic agents for vaccines, mercurochrome, bactericidal agents, agricultural chemicals, etc.);
- lighting (fluorescent bulbs, CCFL);
- industrial use (commutators, relay contacts, etc.);
- vinyl chloride and alkali chloride industries), and
- other usage (paints, pigments, plating, cosmetics, etc.)
Global Mercury Consumption in 2005
More than 60% of the global amount of mercury used in 2005 (about 3,800 tons) was in industrial use, including small-scale gold mining. (The amount of mercury used in Japan during the same period was about 12 to15 tons.)
Demerits of Mercury
Japanese people typically recognize mercury as the synonym for a harmful substance because of the devastating impact of the Minamata mercury poisoning incidents that occurred in Minamata City in Kumamoto Prefecture from the 1950s through to the 1960s, and which gained worldwide attention as a global environmental pollution issue. Organic mercury (methyl mercury) contained in factory effluent was allowed to flow into Minamata Bay, where it then accumulated and became concentrated in plankton and then small fish to large fish through the food chain in the bay. Cats and human beings that then consumed those fish developed serious psychiatric and/or neurologic symptoms.
The health hazard posed by mercury, similar to what occurred in Minamata, has also been experienced in various other parts of the world. In Iraq, for example, 6,500 people were poisoned, with more than 400 dying, by mercury that was present in bread made from wheat that came from seeds treated using germicides containing methyl mercury during the 1960s through to the 1970s.
Primitive refining processes are still used in some gold mining sites due to their cost performance, where an amalgam of alluvial gold and mercury is heated to purify the gold via vaporizing the mercury off. According to reports, a large number of workers that have inhaled vaporized mercury in the refining process suffer from the same symptoms as in Minamata disease.
Other reports describe several cases where trace amounts of mercury contained in underground resources (petroleum, natural gas, coal, etc.) form an amalgam with other metals such as aluminum while passing through the pipelines of oil refineries, which then creates a hole in the pipeline from which gas leaks before resulting in large explosions. Removing any mercury is thus absolutely essential to oil refining companies.
- YAMAMOTO, Yoshihiro. “Harukanaru Suigin no Tabi (Long Journey of Mercury)”, Sanbunsha
- “Suigin (Mercury)”, The Chemical Society of Japan (ed.), Maruzen
- IKUSHIMA, Kenji. “Suigin-shorigijyutsu ga Nihon no Enerugi-kiki o Sukuu (Mercury Treatment Technology Saves the Energy Crisis in Japan)”, CMC Publishing Co. Ltd.
- United Nations Environmental Programme (UNEP): Technical Background Report to the Global Atmospheric Mercury Assessment (2008)
- UNEP Technical Background Report to the Global Atmospheric Mercury Assessment (2008)