Mercury: The silent killer

Anisha Khundongbam *

Element mercury (Hg), liquid form :: Pix - Wikipedia/Materialscientist

It's not been long since I was introduced to the other side of mercury. The only side I knew till then was that of commonly found silver liquid metal with which we sometimes played with our bare hands. But the other side of mercury seemed to be a dangerous unidentified stranger lurking among mankind and ready to plunge out of the dark. I would like to bring to light the lesser known facet of mercury.

What is mercury?

Mercury is a chemical element with the symbol Hg and atomic number 80. It is the only common liquid metal because of which it has earned the common name quicksilver. It is a highly useful metal because of its special combination of weight, ability to flow, electrical conductivity, chemical stability, high boiling point and relatively low vapour pressure. The most unique feature of this metal is that it can exist in solid, liquid or gaseous form.

Its common usage

Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in thermometers, especially ones which are used to measure high temperatures. A still increasing amount is used as gaseous mercury in fluorescent lamps, while most of the other applications are slowly being phased out due to health and safety regulations and is in some applications replaced with less toxic but considerably more expensive Galinstan alloy. Mercury has also been an ideal choice for use in medical devices and materials. It is also being used in several researches and scientific work.

Humans and mercury- the relationship.

Mercury was known to the ancient Chinese, Egyptians and Hindus and has been found in Egyptian tombs dating back to about 1500 B.C. However, there is no proof as to who discovered it and when. Chinese emperors are known to have used mercury to prolong their lives- although in all probability it would have the opposite impact. The relationship between humans and mercury has been a long one from which humans have benefited in many ways but the extent of damage has been equally devastating.

The gravity of damage that can be caused by mercury.

In the history of mankind Minamata disease is etched as one of the biggest disasters caused by mercury where thousands of lives were lost to the poisoning of methylmercury in the industrial waste water of one of the biggest chemical companies in Japan. This highly toxic chemical bio accumulated in shellfish and fish in Minamata Bay which when eaten by the local populace resulted in mercury poisoning.

It has been established that 1 gram of mercury can cause damage to 20 acres of land in multiple ways. At the same time the effect is irreversible as it is highly impossible to extract its effect from the bio-accumulation in plants, animals, soil and water. The adverse effect of mercury poisoning on the human body is reflected in the central and peripheral nervous system and it can damage the brain, spinal cord, kidneys, eyes and liver. Mercury also easily crosses the placenta, passing from mother to unborn child, where it can impact neurological development of the foetus. Inhalation, ingestion, or skin contact are some of the ways of exposure to mercury.

How do we dispose mercury?

Mercury cannot be disposed directly into the environment or along with other common wastes. It needs to be stored under specific conditions until it reaches a designated disposal point. In accordance with the Hazardous Waste (Management, Handling & Transboundary Movement) Rules, 2008 notified under the Environment (Protection) Act, 1986, in consultation with the State Pollution Control Board (SPCB)/ Pollution Control Committee (PCC), the accumulated waste must be safely disposed of within 90 days (Source: Draft report by J.Chandra Babu, Scientist 'C', HWM Division, CPCB, Delhi). The mercury waste generated from Health Care Facility (HCF) can be disposed of at an authorised centralized storage area to be developed by the associations of HCFs located in that region or Indian Medical Association or State Health Department.

Some other options for disposal are through a Common Bio-medical Waste Treatment Facility (CBWTF), Hazardous Waste Treatment Storage and Disposal Facility (TSDF), mercury recovery units or through medical equipment manufacturers.

Why the use of mercury must be eliminated from health care centres?

One of the areas where mercury is most commonly used is the HCF where many equipments and devices contain mercury. Some of the mercury based instruments used for diagnosis purposes by the HCF include
a) Thermometers (used for measurement of body temperatures);
b) Sphygmomanometers (used for measurement of blood pressure);
c) Dental amalgam;
d) Esophageal dilators (also called bougie tubes);
e) Cantor tubes and Miller Abbott tubes (used to clear intestinal obstructions);
f) Laboratory chemicals (fixatives, stains, reagents, preservatives) etc.

The presence of mercury is mainly in clinical thermometers and sphygmomanometers, where breakage results in hazardous spillage which can affect both patients and staff at the hospital, beside the colossal damage that it does to the environment. If the spillage is not managed promptly and efficiently, the affected area may release mercury into vapour and the room, fabric or any other item in contact will continue to produce harmful mercury vapour for years afterward. As per literature accidental spillage of mercury due to thermometer breakage has been estimated at two thermometers per bed per year.

What the Govt, NGOs and hospitals have done to curtail the use of mercury in health care centres.

Mercury thermometers, sphygmomanometers and dental amalgam are significant sources of mercury from the HCFs in the environment. So the drive towards mercury free health care is to eliminate the use of these. Countries such as US, Brazil, Argentina, and Chile etc have taken a call to include Mercury-free Health Care in their national policies and guidelines. India is not far behind, after a report on mercury usage in healthcare in 2004 by Delhi based NGO Toxics link the Govt has taken up several steps to curtail and eventually eliminate the use of mercury in Health care centres.

As a result of a policy issued by the Delhi Department of Health and Family Welfare in 2007, all government-run hospitals have stopped purchasing new mercury-based medical devices. In May 2010 Central Government issued guidelines to phase-out mercury containing equipment from all Government-run Hospitals. Several private systems and philanthropic hospitals in Delhi have also replaced mercury. The trend is rapidly picking up in other states as well.

Shija Hospitals and Research Institute, Manipur has been mercury free since January 2011 and is the first mercury free hospital in Eastern India. It is not far that we will see mercury free being a compulsory feature in all Health care centres.

Do we have an alternative to replace the use of mercury from Health Care Centres?

There are appropriate alternatives which can replace mercury based instruments. If we replace them with good quality non-mercury based equipments it will prevent potential toxic effects of mercury on patients and health care workers as well as humanity in large.

Now that we are aware of the toxicity of this element, our perspective and viewpoint on the use of mercury may change. Although complete wipe out of mercury from the use of mankind is not immediately possible a gradual phase out and replacement of mercury with feasible alternatives can be considered as a huge leap towards a better and safer world.