mercury poisoning, Hg, pollution, contamination, diseases, water body, ships, industries

Mercury poisoning

By: Staff Reporter
Mercury is poisonous in any form. Neurological and behavioural disorders may be observed after inhalation, ingestion or dermal exposure of different mercury compounds.

Mercury is poisonous in any form. Apart from occurring naturally in the earth’s crust, it is released due to volcanic activity and weathering of rocks. It is also released in the atmosphere due to human processes like coal-fired power plants, residential coal burning for heating and cooking, waste incinerators and as a result of mining for mercury, gold and other metals.

According to an October 2012 report ‘Mercury emissions from India and South East Asia’ by Lesley Sloss, a total ‘by-product’ emission from India stands at 171.9 t/year (2005). India ranked second in the top countries for mercury emissions but at 8.93 per cent of the global total, is significantly behind China at 42.85 per cent. The Report states that 87 per cent (140 t/year) of the emissions come from stationary combustion (all fuels). In the decreasing order, the remaining mercury emissions come from cement, non-ferrous metal, caustic soda, pig iron and crude steel production and large-scale gold production.


Mercury in Your Home: A common home appliance containing mercury is the fluorescent lamp. The mercury in the lamp presents no danger when the lamp is intact and undamaged. The same applies to other mercury-containing products like thermometers, LCD monitors, button cell batteries.


Exposure: People may be exposed to mercury by breathing contaminated air, through direct contact with mercury that has leaked from damaged appliances, through the ingestion of aquatic organisms containing mercury or through inhalation by workers during industrial processes.

According to the World Health Organization (WHO), foetuses are most susceptible to developmental defects due to exposure to mercury. It can adversely affect a baby’s growing brain and nervous system. The primary health effect of methylmercury is impaired neurological development. Therefore, cognitive thinking, memory, attention, language, and fine motor and visual spatial skills may be affected in children who were exposed to methylmercury as foetuses.

The second group, says WHO, are people who are regularly exposed (chronic exposure) to high levels of mercury (such as populations that rely on subsistence fishing or people who are occupationally exposed). Among selected subsistence fishing populations, between 1.5/1000 and 17/1000 children showed cognitive impairment (mild mental retardation) caused by the consumption of fish containing mercury. These included populations in Brazil, Canada, China, Columbia and Greenland.


Health Effects: WHO states that elemental and methylmercury are toxic to the central and peripheral nervous systems. The inhalation of mercury vapour can produce harmful effects on the nervous, digestive and immune systems, lungs and kidneys, and may be fatal. The inorganic salts of mercury are corrosive to the skin, eyes and gastrointestinal tract, and may induce kidney toxicity if ingested.

Neurological and behavioural disorders may be observed after inhalation, ingestion or dermal exposure of different mercury compounds. Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches and cognitive and motor dysfunction. Mild, subclinical signs of central nervous system toxicity can be seen in workers exposed to an elemental mercury level in the air of 20 μg/m3 or more for several years. Kidney effects have been reported, ranging from increased protein in the urine to kidney failure.

In the recent past residents of Kodaikanal unwittingly faced the ramifications of working in the thermometer manufacturing plant Hindustan Lever Limited. According to Sarah Hiddlestone’s article, ‘Poisoned Ground’ published in the Frontline (September 11-24, 2010), 23 people died and 550 claim irreparable damage to their health due to exposure to mercury since the plant was set up in 1986. In 2003, 300 t of mercury-contaminated waste was collected from the town, two years after the factory was shut. Although this incident was limited to Kodaikanal and the surrounding areas, India is exposing itself to similar complications in the unchecked spread of mercury laden CFLs. According to the 2012 records put together by the Electric Lamp and Component Manufacturer’s Association, India uses 401 million CFLs amounting to 1804.5 kg of mercury, by conservative estimates.

The Minamata Incident: From 1932 to 1968 Chisso Corporation, a petrochemical company and maker of plastics, discharged industrial wastewater containing high concentrations of methylmercury into the Minamata Bay in Japan. The fish and shellfish from the Bay, an important part of the livelihood and diet for the locals, were contaminated with mercury. The government and company did little to prevent the pollution. It was in May 1956 that the disease was first officially ‘discovered’ in Minamata city. Thousands were crippled and hundreds died agonising deaths due to exposure to methylmercury.


The Minamata Convention: It is against this backdrop that the The Minamata Convention on Mercury—a global treaty by the United Nations Environment Programme (UNEP) to protect human health and the environment from the adverse effects of mercury, was envisaged. The Convention was agreed at the fifth and final session of the Intergovernmental Negotiating Committee in Geneva, Switzerland on 19 January 2013, and was opened for signature on 10th of October. The treaty will take effect 90 days after it is ratified by 50 countries; so far it has been ratified only by USA. As of November 14, 2013, 93 countries have signed this UN treaty. After 2020 each party in the Convention will phase out products that use mercury. The participants of the convention have agreed to reduce emissions of mercury and mercury compounds ‘where feasible’.


CFL and Mercury: According to the Minamata Convention, CFLs with more than 5 mg mercury cannot be manufactured, imported or exported after the phase-out date of 2020. We believe that India may sign the treaty as it has participated in all the discussions and negotiations for the formulation of the convention. With the increasing use of CFLs and the lack of disposal and recycling norms, mercury is surreptitiously entering our food chain through water and food. The country needs to think fast in order to reduce its escalating disease burden and fulfil its oath to provide a healthy and safe environment for its citizens.

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