In The Gambia, mercury is only known to most people as red liquid used to make counterfeit bank notes. Mercury is a chemical element commonly known as quicksilver and was formerly named hydrargyrum. Mercury is an element and a metal that is found in air, water, and soil. It exists in three forms called elemental (or metallic) mercury, inorganic mercury compounds, and organic mercury compounds. Mercury is the only metal that is liquid at room temperature, so it can be found in thermostats and fluorescent lights, some electrical switches and some industrial processes. In its liquid metal form, mercury absorbs instantly into the skin; but it also has a high vapour pressure, so an open mercury container disperses the metal into the air, it is also released into the air when coal and other fossil fuels are burned. It can sticks to clothing and is absorbed by hair and nails.
Inorganic mercury compounds are formed when mercury combines with other elements, such as sulfur or oxygen, to form compounds or slts. Inorganic mercury compounds can occur naturally in the environment. Inorganic mercury compounds are used in some industrial processes and in making of other chemicals. Inorganic mercury salts are used in cosmetic skin creams.
Organic mercury compounds are formed when mercury combines with carbon. Microscopic organisms in water and soil can convert elemental and inorganic mercury into an organic mercury compound, methylmercury, which accumulates in the food chain. Thimerosal and phenylmercuric acetate are other types of organic mercury compounds made in small amounts for use as preservatives.
Methylmercury is an extremely toxic organometallic cation. Its derivatives are the major source of organic mercury for humans. A bio-accumulative environmental toxicant.
The inhalation of elemental (liquid) mercury vapours can cause neurological and behavioural disorders, such as tremors, emotional instability, insomnia, memory loss, neuromuscular changes and headaches. They can also harm the kidneys and thyroid. High exposure can also lead to deaths.
The toxicity of mercury depends on the form of mercury to which people are exposed. The toxic effects of mercury, especially in the case of methylmercury, may be taking place at lower concentrations, but this is proving difficult to establish because the suspected toxic effects are subtle and their mechanisms complex. Methylmercury is of particular concern because it can accumulate in the food chain to reach high concentrations (bio-magnification).
Methylmercury is special among organic mercury compounds because large numbers of people are exposed to it. Its presence in food, such as fish, is a health hazard because the body absorbs it through the stomach and intestines. It poison the nervous system and, can harm the development of the unborn baby’s brain if exposure was during pregnancy. Studies suggested that increases in exposure may affect the heart and circulatory system. Methylmercury has been classified by International Agency for Research on Cancer (IARC) as “possibly carcinogenic to humans” (Group2B).
Elemental mercury is poisonous to the nervous system, and exposure is by inhaling vapours which are then absorbed into the body via the lungs and move from the blood stream into the brain. The main source of elemental mercury vapour is dental amalgam (tooth filling). Fish is generally the main source of both inorganic and organic mercury. Methylmercury the most common organic form, is found in fish and other sea foods.
Work places such as chlor-alkali plants, mercury mines, thermometer factories, refineries, dental clinics, mining and manufacturing of gold extracted with mercury can be sources of exposure. People can also be exposed from mercury compounds used in skin-lightening creams, soaps, some traditional medicines, air and water pollution.
Mr. Baboucarr Mbye
Stay Green Gambia (SGG)
(Ref.: Green Facts: Facts on Health and the Environment)