What is mercury?

Mercury exists in three forms, metallic mercury, inorganic mercury and organic mercury. Metallic mercury is a silver-white metal that is liquid at room temperature. Inorganic mercury compounds contain mercury as well as sulphur, oxygen or chlorine. They are mostly powders or crystals at room temperature. Organic mercury compounds consist of mercury and carbon, the most common one being methylmercury. This has different toxicological effects than the other two forms and is not considered in this review.

How does mercury get into the environment?

Small amounts of mercury exist in the environment in soil, water and air owing to natural and anthropogenic processes. Metallic and inorganic mercury get into the environment from mining ore containing mercury, from emissions of coal-fired power plants, from burning waste containing thermometers, batteries or electrical switches and during the production of cement. Organic mercury is formed in terrestrial environments by micro-organisms present in the soil.

How will I be exposed to mercury?

The presence of mercury in the environment does not always lead to exposure. Clearly, in order for it to cause any adverse health effects you must come into contact with it. You may be exposed by breathing, eating, or drinking the substance or by skin contact. Following exposure to any chemical, the adverse health effects you may encounter depend on several factors, including the amount to which you are exposed (dose), the way you are exposed, the duration of exposure, the form of the chemical and if you were exposed to any other chemicals.

Everyone is exposed to mercury to a small extent as it is naturally occurring in the environment in air, water and food. People may be exposed to mercury from amalgam fillings, which contain 50 % mercury. Once the amalgam has hardened, minute amounts of mercury may be released into the air or saliva due to corrosion of the surface. Mercury from fillings is thought to account for about the same amount of exposure as that from the diet, and therefore does not pose a significant health risk. People may be exposed to metallic mercury vapour if they come into contact with broken thermometers, fluorescent light bulbs, thermostats or barometers. Metallic mercury and vapours are difficult to remove from household furniture and clothing. After spillages items must be thoroughly cleaned to prevent a continuous exposure. Handling contaminated soil may also be a potential source of exposure to mercury.

Occupational exposure to mercury can occur in a number of work places that use mercury, such as in factories making electrical equipment or thermometers or chemical processing plants. Dentists may be exposed to metallic mercury vapour whilst making fillings. 

If there is mercury in the environment will I have any adverse health effects?

Breathing in high amounts of mercury vapour for a short time damages the lining of the mouth and lungs, causing breathlessness, coughing, burning sensation in the lungs and chest pains. Damage to the nervous system may also occur, causing irritability, nervousness, tremor and visual disturbances. Other effects such as stomach irritation, nausea, vomiting, diarrhoea, skin rashes, eye irritation and increased blood pressure may also occur. If small amounts of mercury are inhaled over a long period, such as in a work environment, the lining of the mouth and lungs may be damaged.

Swallowing inorganic mercury can cause stomach irritation, leading to nausea, vomiting and diarrhoea. Ingesting large amounts of inorganic mercury can cause stomach ulcers.

All forms of mercury accumulate in the kidney causing kidney damage, although this is largely reversible when mercury is removed from the body.

Can mercury cause cancer?

International Agency for Research on Cancer classified elemental mercury and mercury compounds as category 3 carcinogens i.e. not classifiable as to the carcinogenicity to humans.

Does mercury affect children or damage the unborn child?

Effects seen in children following exposure to mercury are similar to those seen in adults. Breathing in metallic mercury over a short period of time can cause lung, stomach and intestinal damage. Short term exposure to inorganic mercury can cause increased blood pressure and heart rates as well as weight loss, swollen gums, diarrhoea, abdominal pain and muscle twitching, as well as kidney damage.

If exposed to metallic or inorganic mercury for a long period, children may develop acrodynia, resulting in muscle cramps, irritability, skin redness, peeling of skin, itching, fever and sweating.

Few data have been reported on the possible adverse effects of inorganic mercury on reproductive function or during pregnancy and lactation.

There is no evidence that maternal dental amalgams cause fetal abnormalities.

What should I do if I am exposed to mercury?

You should remove yourself from the source of exposure.

If you have got mercury on your skin, remove soiled clothing, wash the affected area with lukewarm water and soap for at least 10 - 15 minutes and seek medical advice.

If you have got mercury in your eyes, remove contact lenses, irrigate the affected eye with lukewarm water for at least 10 - 15 minutes and seek medical advice.

If you have inhaled or ingested mercury seek medical advice.

What should I do if I spill mercury or break a mercury-containing device?

A step-by-step guide to cleaning up spills of mercury is available online at the following URL: http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1195733821650

 

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