The Prevention of Food Adulteration Act (1955) aims to protect consumers from adulterated food and ensure food safety. These rules declare mercury as a poisonous metal and limit its concentration in fish to 0.5 ppm and in other food items to 1.0 ppm. Methyl mercury is one of the more dangerous forms, and its concentration in fish is limited to 0.25 ppm. The Bureau of Indian Standards (BIS) has laid down safety limits for drinking water at 0.001 mg of mercury per litre.The WHO and the Food and Agriculture Organisation (FAO) have specified limits on the concentration of methyl mercury for fishes. On the basis of risk assessments, a number of countries have stipulated levels of daily or weekly mercury intakes.
Mercury being sold in highly unsafe conditions in a Delhi market
The symptoms of methyl mercury poisoning are varied and can mimic other illnesses. Many of the symptoms take a number of weeks, or even months, to appear. The symptoms include tingling and numbness of extremities; depression, emotional instability, memory reduction, irritability; defects in hearing, vision and speech;difficulty in writing, delays in motor and language development, inability to walk properly, tremors, and in extreme cases, death.
Not surprisingly, the International Chemical Safety Council of United Nations rates methyl mercury an organic form of mercury as one of the six most serious pollution threats to the planet. Methyl mercury intake through fish and other aquatic foods has a considerable effect on human health. Some surveys that provide information on the percentage of mercury originating from fish assume that the percentage of methyl mercury ranges from 60 to 90 per cent. This implies that fish and fish products that we eat can be a major source of methyl mercury. Unborn foetuses are particularly at a high risk from methyl mercury poisoning. Methyl mercury can cross the placental barrier and cause foetal brain damage without any symptoms in the expectant mother.
The situation is India not a happy one. The first global study on mercury has said recently that India could be one of the dozen hot spots after the rise in mercury emissions over 30 years. Launching the Global Mercury Assessment Report in Nairobi, UNEP executive director Klaus Toepfer said action is essential. The report says that coal-fired power stations and waste incinerators account for about 1,500 tonnes, or 70 per cent of new quantified manmade mercury emissions annually. The biggest share of 860 tonnes is from Asia. The UNEP Governing Council has said that there is sufficient evidence of significant global adverse impacts to warrant international action aimed at reducing the risks to human health and the environment, which arise from the release of mercury into the environment.
Mercury has over 3,000 industrial uses. The largest consumer of mercury in India is the chlor-alkali industry, which manufactures caustic soda and chlorine as a by-product using the mercury cell process. The second-largest consumption of mercury in India is for the production of measuring instruments such as thermometers, barometers, etc. It is also used in manufacturing electrical apparatus, mercury vapour lamps, electrical switches, fluorescent lamps, etc. Recent studies have shown that the total mercury pollution potential from coal in India is estimated to be 77.91 tonnes per annum, if average concentration of mercury in coal is assumed to be 0.272 ppm. About 59.29 tonnes of mercury per annum is mobilised from coalfired thermal power plants alone.11 The five super thermal power plants in the Singrauli area, which supply 10 per cent of Indias power, are responsible for 16.85 per cent or 10 tonnes per annum of total mercury pollution through power generation.
Some of the major rivers tested for heavy metals by the Industrial Toxicological Research Centre (ITRC), Lucknow, were found to contain mercury in alarming levels. Testing of seawater by the National Institute of Oceanography, Goa, found increased mercury concentrations in the Arabian Sea. Several studies on fish and prawns in Mumbai, Kolkata, Orissa, etc, have reported alarming rates of mercury concentrations.
A recent study conducted by the Environmental Science Department of the Guru Gobind Singh Indraprastha University, Delhi, reveals that the concentration of contaminants like arsenic, mercury, nitrates, etc, in the groundwater of Delhi exceeds the permissible limits. The study entailed 50 samples of groundwater being lifted from random spots along a 22-km stretch between Palla and Okhla. The mercury concentration in some samples was as high as 4.6 ppm, 460 per cent above the permissible limit. This alarming presence of mercury in groundwater can be traced to the continuous discharge of sewage and industrial effluents into the Yamuna and, subsequently, into the groundwater aquifer which, being sandy in nature, allows mercury pollution to spread at a rapid rate.
However, in a country like India where a large percentage of the population eat fish as a staple food, no provisions for daily or weekly mercury intake levels have been set down. A number of samples of groundwater in some industrial belts (Gujarat, Golden Corridor) have shown concentrations of mercury higher than safe standards. A study shows levels of mercury to be very high as compared to the permissible limit.
Still, mercury hazards have been addressed by citizen action several times in the recent past. In 2001, an active campaign led by several environment groups both from India and the USA turned back a Mumbai-bound cargo ship carrying close to 20 tonnes of mercury reclaimed from a Maine factory in the USA. The campaign was successful in highlighting the harmful effects of mercury and put pressure on the government to stop the USA from dumping its mercury in India.
Hindustan Lever Ltd, an Indian subsidiary of Unilever (an Anglo-Dutch multinational) with a thermometer plant at Kodaikanal, has been found guilty of dumping its mercury waste. HLL had closed down its thermometer factory at Kodaikanal in March 2001. The company recently announced that it had exported mercury wastes from its Kodaikanal plant to the U.S.
The ultimate goal for civil society and industry must be to eliminate mercury use. Alternatives to almost every major use of mercury exist and are documented in the factsheet that accompanies this article. Urgent policy intervention based on alternatives (documented in the accompanying facthsheet) is needed both at the national and state levels, for altering Indias mercury consumption pattern. Meanwhile, it is critical that mercury emissions in municipal and industrial waste streams is reduced. Several international pressure groups are also working to ban the use of mercury.
