Durban - It is rated as one of the top 10 chemical poisons endangering human health and the natural world.Tiny drops of this poison can be found in human teeth, in fresh fish, in light bulbs, paints, batteries and even cosmetics. And it is in the air, water and soil everywhere, in varying amounts.But from Wednesday, the clock starts ticking for world governments, industry and other groups to ban or gradually phase out products and processes that rely on mercury.In terms of the Minamata Convention, a United Nations treaty which came into force on Wednesday, the treaty provides for a complete ban on any new mercury mines, the gradual phase-out of mercury in several household and industrial products and tougher measures to store or get rid of mercury wastes.One of the most immediate results will be the phasing out of old-fashioned thermometers and other mercury-containing medical devices in hospitals before 2020.Eskom, the cement industry and other local industries that generate mercury will also come under government pressure to gradually reduce the volume of mercury entering the air, water and soil by installing new pollution-control technology. Dentists will be compelled to use new composite fillings with no mercury. UN Environment Programme, Time to Act, 2013. (Supplied) UN Environment, the United Nations specialist agency set up to care for the global environment and related human-health issues, says this toxic heavy metal is regarded as one of the top ten chemicals endangering human health and the environment because it damages the human brain, heart, kidneys, lungs, and immune system - particularly in unborn children and babies.The Minamata Convention is named after the Japanese city where nearly 2 000 people died and more than 10 000 others were poisoned several decades ago by a crippling neurological disease after eating fish poisoned by toxic waste dumping by the Chisso Corporation (The corporation later paid out at least $86m compensation to some of the victims and their families).Closer to home, several workers were killed or crippled after handling this toxic heavy metal at the British-owned Thor Chemicals factory in Cato Ridge, KwaZulu-Natal, in the early 1990s.No cure for mercury poisoningMercury is a powerful neurotoxin which can lead to blurred vision, tremors, brain damage, coma and death.A subsequent study by the SA Medical Research Council found mercury levels above World Health Organisation (WHO) standards in 20% of people whose hair samples were analysed in the vicinity of Inanda Dam outside Durban.Half the fish samples were above WHO guidelines and 22% of soil samples taken near the dam were also considered problematic, leading to a ban on fishing at Inanda in 2008.In its vapour form, mercury can be transported over vast distances by wind and water. For example, mercury given off from burning coal at an Eskom power station could wind up as far away as Scandinavia and the Arctic.Mercury poisoning has also given rise to the expression "mad as a hatter", because the chemicals used in early hat-making processes included mercury.According to UN Environment, burning coal to produce electricity and energy is one of the biggest man-made sources of mercury pollution in the air - though emissions can be reduced by up to 95% by improving coal and industrial plant performance and pollution abatement technology.The cement manufacturing industry is estimated to have generated 9% of total man-made emissions of mercury to air in 2010. Mercury may also be released to the soil, in wastes and residues and in the cement product itself.Welcoming the legal introduction of the Minamata Convention in a statement on Wednesday, UN Environment said governments that are party to the treaty (including SA) are now legally bound to take a range of measures to protect human health and the environment by addressing mercury throughout its life cycle."The Minamata Convention shows that our global work to protect our planet and its people can continue to bring nations together. We did it for the Ozone layer and now we're doing it for mercury, just as we need to do it for climate change - a cause that the Minamata Convention will also serve. Together, we can clean up our act," said Erik Solheim, head of UN Environment.He said there is no "safe level" of exposure to mercury, nor are there cures for mercury poisoning, which at high levels causes irreversible neurological and health damage.15 million workers exposedUnborn children and babies are the most vulnerable, along with populations who eat fish contaminated with mercury, those who use mercury at work, and people who live near a source of mercury pollution.A 2017 study comparing mercury levels among women of child-bearing age in the Asia and Pacific regions revealed high traces of mercury in 96% of the women tested from Pacific communities who have high fish diets.As part of the new convention agreements, the Global Environment Facility (GEF) has been charged with raising and disbursing grants for projects to reduce and eliminate mercury pollution."On behalf of the GEF, I am delighted to join others in the international community and celebrate the entry into force of the Minamata Convention on Mercury. We are ready to continue to support a wide range of activities including inventories, implementation plans, and investments in technology for reduction and elimination of mercury," said Naoko Ishii, the GEF chief executive and chairperson.UN Environment says up to 8 900 tons of mercury are emitted each year. It can be released naturally through the weathering of mercury-containing rocks, forest fires and volcano eruptions, but significant emissions also come from human processes, particularly coal burning and artisanal and small-scale gold mining. Communities in Gauteng and Mpumalanga who live in close proximity to coal mines and coal-fired power stations may be at a higher risk of being exposed to toxic mercury released into the air when coal is burned to generate electricity. (groundWork) Mercury mining alone is believed to expose up to 15 million workers in 70 countries to mercury poisoning, including child labourers.Other human activities that may be sources of mercury pollution include the production of chlorine and some plastics, waste incineration and use of mercury in laboratories, pharmaceuticals, preservatives, paints and jewellery.Since the element is indestructible, the convention also stipulates conditions for the interim storage and final disposal of mercury waste.The first official meeting of the 128 countries that signed the treaty will take place from September 24 to 29 in Geneva, Switzerland.Visit The Minamata Convention for further details.