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UN agrees new treaty to reduce harm from mercury

A long-awaited treaty, agreed by UN member states at the end of January, aims to reduce emissions of highly toxic mercury, especially in developing countries. Tony Kirby reports.

On Jan 10, 2013, the UN Environment Programme (UNEP) released its long-awaited report Mercury: Time to Act. The report was aimed directly at the 140 countries that agreed in 2009 to negotiate a legally binding treaty to cut mercury emissions from human activities. On Jan 21, Geneva hosted these 140 countries to finalise this treaty. The meeting was named the Minamata Convention after the Japanese city devastated by mercury pollution in the 1950s and 60s.

Mercury is abundant in high-income and developing countries alike. It is found in electrical switches and thermostats, lamps, and dental amalgam fillings. Mercury as a compound is used in products such as batteries, paints, and creams. It is also found naturally in coal and is used extensively in artisanal mining for gold across Africa and South America. Mercury can be released into the environment via industrial processes including mining, metal and cement production, and burning fossil fuels, as well as building up in the food chain. “Mercury is especially but not uniquely a threat to the health of pregnant women and babies worldwide through the eating of contaminated fish, for example, or to marine mammals in places like the Arctic”, says Achim Steiner, UN Under-Secretary General and Executive Director of UNEP.

The report underlines that the burden of mercury disease is shifting towards developing countries, in particular, those where more coal burning is increasing emissions of mercury into the atmosphere. “Small-scale gold mining using mercury is also aggravating the threat, in part fuelled by the high global gold price”, adds Steiner.

A map produced by the Artisanal Gold Council, a non-profit organisation, shows many countries in Africa, especially Sudan, as well as China, Peru, Bolivia, Ecuador, and Colombia, all emitting more than 50 tonnes of mercury per year through artisanal mining. Meanwhile, mercury emissions are declining in North America and Europe.

WHO, which has welcomed the treaty, had previously concluded that there are no safe limits in respect to mercury, and, especially in high-income countries, many mercury-containing products are already being phased out, with processes using mercury increasingly being converted to alternative technologies. WHO itself undertakes a range of activities to mitigate damage from mercury, including establishing an evidence base for mercury amalgam fillings in dentistry and trying to find alternatives, as well as identifying populations most at risk from mercury poisoning and assisting with any disease outbreaks. “Some countries have issued advisories for the general public to inform pregnant women about fish that contain high levels of mercury, so they can keep their exposure down to protect the developing fetus”, says Carolyn Vickers, Team Leader for Chemical Safety at WHO.

The treaty took 6 years altogether to formulate and there were plenty of sticking points, says Lesley Sloss, a Fellow of the Royal Society of Chemistry, UK, and chair of the forthcoming International Conference on Mercury as a Global Pollutant, taking place in Edinburgh, UK, this July. One such point was the developed world “pushing” the developing world into action. “We in the developed world had our industrial revolution decades ago and are now in clean-up and repent mode. The rest of the world is still scrambling for electric power and modernisation. They are entitled to this—it is nothing that we haven't done already”, says Sloss.

“The treaty confirms that mercury should not be used in small-scale gold mining but accepts that phasing this use out will require a huge change in the way many millions of miners live and work worldwide.” Sloss adds that action plans to phase out mercury are to be drawn up in each country, but cautions that some alternative technologies that replace those involving mercury—such as those involving cyanide or borax—can be just as harmful, but in different ways.

Importantly, mercury-containing thiomersal vaccines were recognised as safe at the UNEP meeting and excluded from the treaty. This decision was welcomed by WHO. 1·4 million lives are estimated to be saved each year by immunisation with thiomersal-containing vaccines.

“This treaty is a really important step forward precisely because its effects will not be seen for a long time. Even if mercury were to be completely eliminated from everything (including coal) now, it would take many decades for the element's spread through the biosphere to start tapering off”, says Andrea Sella, Department of Chemistry, University College London, UK. “By acting now and setting binding targets we are beginning to see a recognition that this is a problem to be taken seriously.”


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