DANGER! - MERCURY POISONING

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The danger of mercury and its compounds has been known for many centuries even as far back as the Greeks and Romans were aware of the toxic nature of mercury.

Metallic mercury usually causes poisoning by ingestion or absorption through the lungs. Mercury (I) is less poisonous because it has a low solubility and so cannot easily move around the body. Mercury (II) and organomercury compounds are highly toxic and can easily be absorbed through the skin. Mercury (II) has a high affinity for sulphur and will affect all sulphur containing compounds especially proteins with disulphide bonds.

The symptoms of acute mercury poisoning are headache, nausea, vomiting and diarrhoea but the symptoms of exposure to small amounts of mercury over a longer period of time are quite different. These involve neurological disorders such as fatigue, memory loss, tremors in the hands, irritability and violent mood swings.

Treatment, especially for acute cases involves chelation therapy where the patient is treated with compounds such as British Anti-Lewisite (dimercaprol) which bind strongly to the mercury in the body and are easily excreted out.

Mercury poisoning was an occupational hazard of hat makers in days gone by because mercury was used to treat the felt used to make hats to make it last longer. Many hat makers suffered from the "hatters shakes" and where the phase "mad as a hatter" probably originates from.

Mercury poisoning was also common in the past centuries because calomel (Hg₂Cl₂) was used as a medicine for many ailments, especially venereal disease. Due to the large amount of sulphur found in hair those affected by mercury poisoning have large amounts in their hair. Such notable figures as Robert Burns and Napoleon were found to have high levels of mercury in their hair as a result of being treated with calomel.