A mercury-containing compact fluorescent bulb. Photo: H. Selin.
Our research for chapter 6 of Mercury Stories led us to a “lightbulb moment” – and not just because mercury was used extensively in lighting-related applications beginning in the 20th century. One of the major surprises of chapter 6 is the wide variety of societal benefits that uses of mercury had over time, in addition to the substantial damages it has caused to the environment and human health.
In chapter 6 of Mercury Stories, we look at intentional uses of mercury in a wide range of products and production processes. We begin the chapter with the story of the mercury thermometer – the dominant temperature-measuring technology for nearly 300 years because of its simplicity, precision, and reliability. While electronic thermometers are increasingly replacing it, the mercury thermometer led to substantial advances in science, meteorology, and medicine. The mercury thermometer is just one well-known example of how mercury has been used to produce consumer goods, and mercury has also been a key component in much chemicals production over the past 100 years.
The story of compact fluorescent bulbs (CFLs), which use small amounts of mercury, illustrated complexities related to weighing costs and benefits of using this toxic substance. CFLs were marketed starting in the 1990s as much more energy-efficient alternatives to the older incandescent bulbs. Similar to other types of fluorescent lamps, CFLs contain a small amount of mercury, whereas incandescent light bulbs do not. However, CFLs uses less energy compared to incandescent light bulbs. Reduced energy use from fossil fuels helps address climate change. And in places where electricity is generated by coal-fired power plants, the related reduction in mercury emissions from the energy sector can result in reduced mercury discharges to the environment. But this is influenced by the degree to which the mercury in discarded CFLs is safely managed.
Other examples of benefits of mercury uses that may not be readily apparent are found in the chemical production sector. The use of mercury in chlorine production was more energy efficient than alternative techniques, which can also help reduce emissions of mercury and other air pollutants if energy for chemicals production comes from coal and other fossil fuels. Further, chlorine that was made using mercury-based production techniques benefited public health – for example, chlorination of water supplies in the early 20th century protected people against waterborne diseases.
These sometimes beneficial uses of mercury in products and processes have at the same time resulted in large amounts of mercury being discharged into the environment, and have put workers at risk (we discuss human health issues in chapter 4). The benefits and costs of mercury uses were thus not equally shared, and the costs were substantial. Along with the story of the benefits of the thermometer to science and innovation is the story of a thermometer factory in Kodaikanal in the Indian state of Tamil Nadu. Built in 1983 with equipment from a decommissioned US plant, the factory was forced to shut down in 2001 by the Tamil Nadu Pollution board after public protests. Workers at the factory were exposed to mercury, and showed symptoms of mercury poisoning. Soils around the factory are still contaminated with mercury, and the process of cleaning up the site continues to be controversial. Chemicals manufacturing was an important part of the industrialization of Japan, but lead to the outbreak of Minamata Disease among local fishers and their families in Minamata. Unsafe handling of mercury from chemical manufacturing plants have also caused severe local contamination issues elsewhere. Further, excess mercury from especially chlor-alkali plants was exported after their closure – some of this mercury made its way to artisanal and small-scale gold mining activities, which is the topic of chapter 7.
In chapter 6, we examine how societies have responded over time to complexities surrounding the benefits and harms of mercury use in products and processes. Many early efforts to develop mercury-free products and processes occurred within the private sector. These were typically driven by economic interests, as mercury-free alternatives were cheaper or otherwise more profitable. More recently, government controls have been instituted because of growing environmental and human health concerns about mercury. Most common commercial products and production processes using mercury are currently being phased out under the Minamata Convention, including mercury thermometers. The Minamata Convention still allows the production of CFLs with small amounts of mercury, but the introduction of newer and more energy-efficient light-emitting diode (LED) lightbulbs that do not use mercury at all shifts the market away from CFLs. Large-scale industrial uses of mercury are mostly in the past, but the negative environmental and human health impacts and related economic clean-up costs of these uses will persist long into the future.