This crackdown certainly has a few cracks in it. Activists have criticised loopholes in a new treaty, signed by 140 countries, that will control mercury pollution. But at least the Minamata Convention on Mercury does commit countries to reducing their mercury emissions.
The convention, named for a Japanese city that suffered severe mercury pollution, aims to control global mercury levels. Products like batteries and thermometers that contain mercury will be phased out by 2020, while major sources like coal-fired power stations will have to obey new and stricter rules.
Mercury is a powerful neurotoxin that accumulates as methylmercury in the environment and in the bodies of marine animals. It causes developmental problems and physical deformities in humans, is lethal in acute cases, and affects animals' ability to reproduce. The World Health Organization says it is not possible to estimate how many people are killed or injured by mercury globally, mostly because there is not enough data on exposure, but the harm done to heavily exposed populations is significant.
According to the UN Environment Programme's Global Mercury Assessment 2013, about 1960 tonnes of mercury were released into the air in 2010, and at least another 1000 tonnes into water. The biggest sources are artisanal small-scale gold mining
Loopholes?
But the treaty is weak on both points, says Elena Lymberidi-Settimo of the European Environmental Bureau in Brussels, Belgium. For instance, while the treaty encourages countries to draw up action plans to cut mercury use in artisanal gold mining, no targets or dates are specified.
That is because most artisanal gold mining is illegal and therefore difficult to track, so there's little point setting targets, says Tim Kasten, head of the chemicals branch of UNEP in Geneva, Switzerland. Instead, the treaty focuses on providing information and technologies to the miners that will both improve their health and reduce the amount of mercury they release. "This is the most that can be done," he says.
Miners are using mercury to separate gold from its ore, then burn it off with a torch. Instead, Kasten wants them to use retort flasks that recover 80 per cent of the mercury, which they can later reuse. The system limits their exposure and the amount that is released into the environment.
Lymberidi-Settimo also criticises the treaty's rules on coal burning, the second biggest emitter of mercury. New coal-fired power plants must use the best available technology to cut emissions. But where existing plants are concerned, nations can choose to cut emissions by as little or as much as they wish.
However, Kasten says that while the rules are looser for existing coal facilities, they still have to cut emissions. "It's not a complete walk-away, there are things they will be required to do," he says.
Kasten says global mercury emissions should start to fall in the 2020s. It will then take a few decades for exposure rates to drop, as so much mercury has built up in the environment. "This is still going to take some time," he says. "But we have to start now."
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