Introduction

Mercury (Hg) is a naturally occurring shiny silver-white heavy metal which is present in air, water and soil. It has been used for medicinal and industrial purposes for centuries. But the exposure to mercury is toxic to humans, especially, fetus and infants, as well as to the environment. Mercury exists in various forms which have different levels of toxicity.

Classification

There are mainly three types of mercury:

1. Elemental/ Metallic – Liquid at the room temperature and less toxic than the other two forms of Hg.

2. Inorganic – Present in vapor form and exposure is possible through human occupation.

3. Organic – Methylmercury, which may enter human body through their diet like contaminated fish.

Key Facts

• Mercury is found in the earth’s crust which gets released into the environment by volcanic eruptions, rock weathering and some human activities like coal-fired power stations, residential coal burning, mining of Hg, gold and other metals, etc.
• Organic mercury is most dangerous form of the mercury (methylmercury) that is found in contaminated fish or shellfish diet. Another form of organic mercury (ethyl mercury) used as preservative in some vaccines is without any health risk.
• Mercury has adverse effects on nervous, digestive, renal and immune systems.

Factors Determining the Severity of Health Effects

• Mercury type
• Dose of mercury
• Age of the person (foetus, child or an adult)
• Duration of the exposure
• Route of exposure (inhalation, ingestion or through skin)

Health Effects of Mercury

• Developmental effects on foetuses mostly on brain and nervous system like impaired neurological development, effects on cognitive thinking, memory, language, and motor skills.
• Occupational and consumption hazards include mental retardation.
• In Japan, between 1932-68, 2000 cases of Minamata disease were found due to consumption of mercury contaminated fishes with signs of brain damage, paralysis, incoherent speech and delirium.
• The inhalation of mercury can cause symptoms like tremors, insomnia, memory loss, neuromuscular effects, headaches, and cognitive and motor dysfunction.
• The renal system is also affected including increased protein in the urine and kidney failure.

Children are much vulnerable to mercury than the adult population due to certain childhood behaviors and unique susceptibilities.

Signs and symptoms of acute mercury intoxication

Inhalation – Harmful effects on nervous, digestive and immune system along with adverse effects on lungs and kidneys. These effects can also be fatal.

Exposure to large quantity of mercury vapor can lead to pneumonitis.

Ingestion- Corrosion of skin, eyes and gastrointestinal tract.

Precipitation of intestinal mucosal proteins, mucosal necrosis, abdominal pain, bloody diarrhea, and shock are seen if there is ingestion of mercuric chloride.

Some neurological and behavioral disorders like tremors, insomnia, memory loss, headaches and cognitive and motor dysfunction are also seen by mercury ingestion, inhalation or skin exposure.

Management of Mercury toxicity

There’s no cure for mercury toxicity. Elimination of exposure is the best way to stop mercury toxicity. If mercury levels reach a certain point, chelation therapy may be advised by the doctor.

Reducing Human Exposure to Mercury

• Promoting clean energy (not burning coal)
• Stopping mercury use in mining of gold and other industrial processes
• Safe handling and proper management of mercury-containing products like batteries, thermometers, lamps, dental amalgam, cosmetics etc.
• Health education and policy making for primary prevention

To Know about mercury- Click here

To know more about, how to keep health care mercury free –Click here

References

https://www.who.int/en/news-room/fact-sheets/detail/mercury-and-health

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3253456/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096006/