Q. Consider the following statements regarding mercury pollution :

1. Gold mining activity is a source of mercury pollution in the world.
2. Coal-based thermal power plants cause mercury pollution.
3. There is no known safe level of exposure to mercury.

How many of the above statements are correct?

• Only one
• Only two
• All three
• None

Answer: (c) All three

Notes:

• Gold mining is poisoning Amazon forests with mercury. To separate the gold, miners mix liquid mercury into the sediment, which forms a coating around the gold.
• Fly ash generated by TPPs is one of the ways mercury is released into the environment. Fly ash is usually disposed in ash ponds in the form of ash slurry, forming an aquatic ecosystem of its own. Coal-based TPPs are the major source of mercury – the ninth most toxic element found on earth — emissions into the environment. Mercury contributed over 80 per cent of emissions released by the TPPs, according to 2016 estimates by Delhi-based think-tank Centre for Science and Environment.
• Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. To date, there are no universal diagnostic criteria for mercury overload.

Mercury Pollution

• Mercury is a naturally occurring element that is found in air, water and soil.
• Mercury is a toxic heavy metal that can cause serious health problems in humans and animals.
• It is released into the environment from natural sources, such as volcanoes, and from human activities, such as gold mining and coal burning.
• Mercury occurs naturally in the earth’s crust, but human activities, such as mining and fossil fuel combustion, have led to widespread global mercury pollution. Mercury emitted into the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish.
• Almost all people in the world have at least trace amounts of methylmercury in their tissues, reflecting its pervasive presence in the environment. Some communities eat significantly more quantities of fish than the general population, and thus may be exposed to much greater mercury contamination than the general population.
• Minamata Disease:
  • A disorder caused by methylmercury poisoning that was first described in the inhabitants of Minamata Bay, Japan and resulted from their eating fish contaminated with mercury industrial waste.
    • The disease is characterized by peripheral sensory loss, tremors, and both hearing and visual loss.
  • Methylmercury is very different from ethylmercury. Ethylmercury is used as a preservative in some vaccines and does not pose a health risk.

Minamata Convention on Mercury

• The Minamata Convention on Mercury is a global treaty to protect human health and the environment from the adverse effects of mercury and its compounds.
• It was agreed at the fifth session of the Intergovernmental Negotiating Committee in Geneva, Switzerland 2013.
• Controlling the anthropogenic releases of mercury throughout its lifecycle is one of the key obligations under the Convention.
• The Convention also addresses interim storage of mercury and its disposal once it becomes waste, sites contaminated by mercury as well as health issues.
• The Convention covers all aspects of the life cycle of mercury, controlling and reducing mercury across a range of products, processes and industries. This includes controls on:
  • mercury mining
  • the manufacture and trade of mercury and products containing mercury
  • disposal of mercury waste
  • emissions of mercury from industrial facilities.
• Countries that have ratified the Convention are bound by international law to put these controls in place.
  • India has ratified the Convention.