Mercury is a chemical substance, a heavy metal, which can be found in its simplest form or as compounds. Man is exposed to mercury from several sources, when the substance reaches a certain level in the blood, signs and symptoms of poisoning appear.
All forms of mercury are poisonous but the vapour appears to be most dangerous as it goes straight through the lungs into the blood.
Mercury poisoning affects the brain, the lungs and the kidneys.
Symptoms and signs include peeling off of the skin, increased heartbeat, high blood pressure, trembling (shakes), pin sensationin the hands and feet, lack of sleep, loss of memory, nervousness, muscle weakness, poor kidney function, brain damage. In high exposure, death results within a few days.
The effect of mercury depends on dose, length of exposure, state of the person exposed (age, pregnant or not, breast feeding or not) and the route (through the mouth, nose or skin).
The list below will let us know how close we are to mercury and mercury poisoning.
Several cosmetics contain mercury as the active ingredient. These cosmetics have skin whitening abilities. When applied to the skin, it is absorbed into the blood and several cases of mercury poisoning resulting from the use of such products have been reported. The use of cosmetics containing mercury has been banned in several countries including Nigeria but they are still been smuggled into the countries as women are bent on making their skin whiter.
Mercury occurs naturally in our environment especially in the soil, it is also released into the air by various activities in factories/plants. Mercury in the air eventually settles in rivers and seas and the aquatic life therein. Mercury in soil is washed into the rivers when it rains. Fish acquires mercury by feeding on things in the water and also other fishes. Consequently, the bigger the fish the more the mercury it contains.
Humans get the mercury when fish is consumed. The following fish have high to medium level of mercury—king mackerel, shark, tuna, grouper, lobsters, swordfish, and tile fish. Pregnant women, breast-feeding women and children are advised to avoid the fish listed above.
Rather, they can eat fish listed now:-salmon, tilapia, catfish, croaker, crayfish, oysters, crabs and sardines.
3. Dental fillings
Some dental fillings contain a little quantity of mercury. Although there are several arguments against any bad effect of its use; that its use poses no risk of mercury poisoning, measurement of urine level of mercury in people with the fillings has shown increase up to the maximum allowable in workers who are regularly exposed to mercury.
Consequently its use for dental filling has been banned in one or two countries.
4. Manufacturing Plants
The burning of coal to run plants causes the release of mercury into the air, long exposure could lead to poisoning. Consequently workers in such factories are advised to go for urine and blood tests at regular intervals to check the mercury levels.
Mercury is used in the manufacture of some batteries especially the small batteries in wrist watches, toys, hearing aids etc. We have to be careful when dealing with such batteries. As for the factory workers they must insist on regular checks for blood mercury levels.
Other sources of exposure include cement plants, gold mines, human crematoria and steel plants, paper industries; all these plants release mercury into the air. The mercury in the air can be inhaled or ingested because the mercury vapour can settle in water bodies (rivers, lakes, streams) and the soil.
Those living near them or working in them are specially exposed.
5. Hydroelectric plants
Hydro-electric plants spew mercury into the air which pollute the air, soil and water. Dams are spread all over the world, serving as major source of electricity.
6. Household Appliances and others
Some household items contain mercury in vapour form. These include fluorescent bulbs, LCD televisions, thermometers, barometers, sphygmomanometer and manometers; some old models of water heaters and washing machines.
Other items near us which contain mercury include the screen of laptop computers.