Last month, representatives from nations around the world met in Japan to sign a landmark convention that seeks to reduce global emissions of mercury. The Minamata Convention on Mercury would require that participating nations restrict the production, import, and export of a wide range of mercury-containing products by 2020.
The treaty’s first line emphasizes that “mercury is a chemical of global concern owing to its long-range atmospheric transport, its persistence in the environment once anthropogenically introduced, its ability to bioaccumulate in ecosystems and its significant negative effects on human health and the environment.” The United Nations Environment Programme (UNEP) has championed international negotiations leading to the mercury treaty for the past several years, and the World Health Organization has also been supportive.
The treaty was signed by more than ninety countries at the public ceremony in Japan last month and will become binding after fifty countries ratify its terms. Some countries, like the United States, will require domestic legislative approval to ratify international treaties.
Each country that ratifies the treaty will be required to phase out mercury from a highly specific list of consumer products by no later than 2020. The list includes soaps and almost all cosmetics, most batteries, a variety of lamps and light bulbs, and pesticides, as well as medical instruments like thermometers and blood pressure devices. Certain chemical production processes also fall within the overall ban.
However, the treaty contains a range of exemptions. Existing coal-fired power plants will not be held to the stringent emissions controls that the treaty requires for new plants. The treaty will not apply to vaccines that rely on thimerosal, a mercury compound, nor to dental fillings—although participating countries are encouraged to “phase down” dental use. Although the treaty calls for a ban on mercury in most cosmetics, mascara and other cosmetics used near the eye are exempt from the treaty on the grounds that no “effective and safe substitute preservatives” for these products exist. The treaty also exempts small-scale and artisanal mining, as well as the manufacturing of certain plastics, although it urges those industries to seek reductions in their mercury emissions.
Concerns about the human health risks of mercury are not new. Scientists recognized the risks of mercury exposure in the 1860s, when they discovered “Mad Hatter” disease among industrial felt hat makers in England. The workers in these facilities inhaled large amounts of mercury every day and began to experience tremors, speech problems, irritability, and mental confusion. Despite this early discovery and the availability of mercury alternatives, the chemical remained popular in a variety of industries throughout the twentieth century.
More than a century after “Mad Hatter” disease was first discovered, mercury poisoning regained international attention in the late 1950s. Thousands of citizens in the Japanese coastal city of Minamata began to suffer from a mysterious and debilitating illness that was eventually linked to consumption of local fish and shellfish contaminated with methyl mercury. A local factory called Chisso Corporation had discharged mercury-laden sludge into the ocean over a period of several decades beginning in the early 1930s, and bioaccumulation of the chemical in marine life slowly poisoned the city’s residents. The neurological syndrome produced by severe mercury poisoning is now known as Minamata disease, or sometimes Chisso-Minamata disease.
The naming of the recent mercury treaty after the city of Minamata has provoked a mixed reaction from local residents. Some see it as a “new step forward” in international recognition of the victims of mercury poisoning who have also often experienced prejudice and discrimination. Others, though, worry that the treaty’s name might tarnish the city’s reputation or trigger rumors.
The treaty remains open for signature by all countries; a running list of participating countries can be found on the Minamata Convention’s website. Although the United States participated in several rounds of negotiations for the Minamata Convention, its delegation left Japan—reportedly because of the federal government shutdown—before the public signing of the convention, which took place on October 10th.
It has been more than a decade since the international community last signed a treaty addressing the impact of toxic chemicals on human health.