Mercury poisoning

[Naveed Yaseen]

By Dr Iqbal Saeed Khan
One of the most harmful elements that industries in major cities of Pakistan regularly get rid of as waste product is mercury. Mercury is a silver chemical element, and is found in liquid form at or near room temperature. It is commonly used in fluorescent light bulbs, coal plants, dental fillings, for the protection of seeds, grains and antifungal agents, as well as in thermometers, manometers, batteries, cells. A small quantity of mercury is even present in cosmetics, whitening creams and lotions.

The problem with this element is that it is harmful for humans in more ways than one. It is a heavy metal and toxic to human subjects, which could lead to a number of diseases. Mercury could create problems in digestive systems as well as cause muscle weakness. Most importantly, it could adversely affect the brain.

When industries let their waste flow into the sea or the rivers, mercury, its compounds and forms are eaten by fish. However, this mercury is accumulated in fishes’ bodies since it is not digestible. The amount of mercury gradually increases owing to the presence of mercury in water.

Humans are exposed to mercury and its toxic compounds through vapours, polluted water and sea food/aquatic fish that live in contaminated water. Methyl mercury which is a type of mercury and perhaps the most toxic one is eaten by fish. Thus, when humans consume seafood, this mercury accumulates in brain tissue, muscles, fat, blood and kidneys, leading to crippling disease.

There is every possibility now that after the recent rains, a considerable amount of mercury or its organic and inorganic compounds may have found their way via drains to the sea. A few years ago, a study determined that the Lyari River has alarmingly high mercury levels. However, we do not know the amount of mercury found in the water bodies during and after the rains.

Mercury causes diseases that could prove to be crippling: hundreds of people were killed by a disease in Japan during the 50s at Minimata Bay. The ailment, now known as the Minimata Disease, was caused by mercury being discharged in the ocean by adjoining industries. The people who suffered from this disease experienced paralysis and damage to the central nervous system, defective vision and anaemia. Expectant mothers gave birth to defective neonates with the same disease back then.

Another example is that of Iraq where about 500 people died owing to the consumption of wheat that was had mercury as an anti-fungal agent in 1972.

In most countries precautions are taken to prevent mercury from entering the human body. Mercury is recycled or cleansed if spilled. However, in our country, the old manometers, thermometers, and batteries — all of which contain mercury — are dealt without any precautionary measures.

The writer is a research fellow at the University of Karachi