Mercury Pollution

Mercury is one metal with three different faces

• Elemental mercury. A silvery liquid metal that can turn into vapour. People breathe it in at mines or after a spill.
• Inorganic mercury. Mercury joined to elements other than carbon, found in some industrial waste and unsafe products.
• Methylmercury. An organic form made mainly by microbes in water and wet sediment. People absorb it mainly by eating contaminated fish.

Good to Know

Where the mercury comes from

• Gold mining. Small mines mix mercury with ore to catch gold, then heat the mixture to release it. This releases mercury vapour into the air.
• Coal and industry. Coal contains tiny traces of mercury. Burning huge volumes worldwide adds up to a large total release. Metal smelting and waste burning add more.
• UNEP’s 2018 global assessment estimated small-scale gold mining caused about 37% of human mercury pollution. This is an estimate, not a fixed yearly share.

Natural sources like volcanoes and slow rock weathering also release mercury, but human sources add far more to the food chain.

Five steps from a source to a meal

• Release. A mine, coal plant, or other source releases mercury into the air.
• Travel. Mercury moves through the air and settles on land or water.
• Change. Microbes in water and wet sediment convert some of it into methylmercury, the form that enters food chains.
• Food web. Small water organisms absorb methylmercury. Fish eat those organisms, and larger fish eat smaller fish.
• Exposure. People and wildlife take in methylmercury by eating contaminated fish.

Good to Know

Two kinds of build-up

• Bioaccumulation is methylmercury building up inside one living thing over time.
• Biomagnification is its level rising across each food-chain step, since a large predator eats many smaller fish.
• This is why long-lived predatory fish carry far more methylmercury than small fish, even though the surrounding water has a much lower level.

Mercury targets the nervous system

• Children developing in the womb are especially vulnerable to methylmercury.
• High or repeated exposure can affect memory, movement, and learning.
• Some mercury forms can also harm the kidneys or lungs.

Good to Know

Three routes of exposure

• Food. Eating methylmercury in contaminated fish and shellfish. Risk rises with the fish type and how often it is eaten.
• Work. Gold miners can breathe vapour while heating an amalgam, the mercury mixture that traps gold.
• Home. A broken mercury thermometer can release droplets and vapour. Some unverified skin-lightening products may also contain mercury.

The world’s treaty on mercury

The Minamata Convention on Mercury was adopted in 2013 and came into force in 2017.

• It bans new mercury mines and sets an end date for existing ones.
• It limits mercury in listed products and industrial processes.
• It calls for controls on releases to air, water, and land.
• It asks countries to reduce mercury use in small-scale gold mining and manage mercury waste safely.

What applies on the ground

India ratified the Minamata Convention on 18 June 2018. It registered extra time for listed mercury-added products until 2025, and a separate acetaldehyde-process exemption ran until 2023.

• The CPCB sets a mercury emission limit of 0.03 milligrams per normal cubic metre for thermal power plant exhaust gas. This is an air-emission limit, not a safe personal dose.
• FSSAI has a laboratory method for testing methylmercury in fish, which helps authorities check food safety without implying every fish species carries the same level.

Where the treaty gets its name

A factory in Japan released wastewater containing methylmercury into Minamata Bay. Local families ate the contaminated seafood for years, and people developed serious nerve and movement problems. Children could be harmed before birth. This illness became known as Minamata disease, and the treaty carries its name as a warning about unchecked pollution.

Great to Know

Three layers of prevention

• At the source. Replace mercury-based gold extraction where possible, control coal-plant emissions, and handle mercury waste safely.
• At the fish market. Eat a variety of fish. People who are pregnant or feeding young children should choose lower-mercury species, but should not stop eating fish altogether.
• At home. Choose mercury-free thermometers, avoid unverified skin-lightening products, and never sweep or vacuum a mercury spill. Ask local health or waste authorities for safe disposal advice.

COP-6 sets a 2034 phase-out for dental amalgam

Treaty parties met in Geneva in November 2025 for the Minamata Convention’s sixth Conference of the Parties (COP-6) and agreed to a binding new global deadline: mercury dental amalgam must be phased out worldwide by 2034, with a narrow clinical-necessity exemption.

• COP-6 adopted 22 decisions in total. One rule requires countries to submit data on mercury-compound supply, use, and trade to the treaty Secretariat by 31 March 2026.
• That data will feed a possible future Annex covering mercury compounds not yet regulated by the treaty.
• COP-6 also strengthened guidance for national action plans on artisanal and small-scale gold mining. India was among the countries that requested changes to this draft decision text.

India’s first ICMGP

Separately, Hyderabad is scheduled to host the 17th International Conference on Mercury as a Global Pollutant (ICMGP-17) at IIT Hyderabad in October 2026. Organisers confirm this is the first edition of this conference held in India.

• Its theme looks toward ten years of enforcement of the Minamata Convention, which entered into force in August 2017.
• This marks one decade of enforcement, not two, since the treaty is not yet twenty years old.