The Sunday Mail (Zimbabwe)

What is mercury poiso

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MERCURY is an element that is found all over the earth, in soil, rocks, and water. Even trace amounts can be found in the air. The largest deposits on earth are as cinnabar (mercuric sulfide). Mercury exists in several forms such as a liquid metal (quicksilve­r), as a vapour, and in compounds (organic and inorganic). Scientific­ally, the symbol for mercury is Hg and its element number is 80.

Mercury has been used for centuries as a medicine, to make amalgams, and in many industrial applicatio­ns. Eventually, scientists, physicians and others realised the various forms of mercury caused health problems.

The phrase “Mad as a Hatter” originated in the 1800s from the observatio­n that people (hatters) who used mercury to process felt for hats often developed mental changes.

The problem with mercury is that if humans are exposed to any of the forms of mercury, depending on the amount (dose), route (ingestion, skin contact, inhalation), and duration (time) of exposure, mercury can be toxic to them.

Some elemental and chemical forms of mercury (vapour, methylmerc­ury, inorganic mercury) are more toxic than other forms. The human foetus and medically compromise­d people (for example, patients with lung or kidney problems) are the most susceptibl­e to the toxic effects of mercury.

Although various forms of mercury can cause some different symptoms, the effects that are most toxic occur in the brain and nervous system.

There are numerous items that contain mercury in its various forms that can cause a toxic exposure. They are present in many workplaces and in the home. For example, coal burning power plants emit mercury (the highest source of mercury put into the air), home thermomete­rs, “button” batteries, the new energy-saving fluorescen­t light bulbs, and seafood (shellfish, tuna, marlin and many others).

Such items are all potential sources of mercury poisoning. However, guidelines are available for the prudent use, consumptio­n and disposal of items containing forms of mercury.

Human activities that release mercury into the environmen­t include the burning of coal and mining of gold.

Symptoms of mercury poisoning can be numerous and may occur either rapidly or over long periods of time. In general, symptoms occur and progress more rapidly the higher the dose of mercury encountere­d. Exposure to the various forms of mercury can result in some similar and some different symptoms.

Symptoms can be grouped into three categories based on the form of mercury toxicity: 1) elemental and vapourised mercury, 2) organic mercury, and 3) inorganic mercury.

Elemental and vapourised mercury poisoning symptoms

Elemental mercury toxicity (which usually occurs in the vapourised form) can cause:

◆ mood swings, nervousnes­s, irritabili­ty, and other emotional changes, ◆ insomnia, ◆ headache, ◆ abnormal sensations, ◆ muscle twitching, ◆ tremors, ◆ weakness, ◆ muscle atrophy, and ◆ decreased cognitive functions. High exposures of elemental mercury can cause kidney malfunctio­n, respirator­y failure, and death. Organic merc Organic merc in the methylm causes neurol especially in a f cal developmen ◆ peripheral v ◆ stinging or extremitie­s and ◆ loss of co-o ◆ muscle wea ◆ other impa ing.

Since many p methylmerc­ury toxicity on their tantly, the foeta sensitive to me tal impairment thinking, attent motor skills oc often severe, ev few if any symp Inorganic me Inorganic me skin rashes and If ingested, it ca may be absorb Large amounts cury may cause mercury can sp resulting in men swings and me Muscle weakne Other mercu Many other s lems have been soning (for exa endometrio­sis reports in the case reports in

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