Air, water and soil: all have varying amounts of toxic heavy metals. Gradually, they are entering the human body through the food chain. Down To Earth reports on the extent of the problem in India

-- A s early as 1979, a working group, established by the government of India to review problems related to heavy metal pollution, recommended an Integrated Environmental Programme on Heavy Metals ( iephm) project to be coordinated by the late C R Krishna Murti. The group's report was published in 1991. The warning bell sounded. But soon, all was forgotten (see box: A caution unheeded ).

Then came the Indian Council of Medical Research ( icmr) report in 1993, followed by another in 1996 ( icmr reports on food contamination, 1993, and 1996 ). The icmr reports seconded what Murti had to say: heavy metals are present in excess in the air, water and soil and they have severe detrimental effects on all life forms. But two decades since the first warning, these reports have only gathered dust.

Unlike organic pollutants, heavy metals are indestructible poisons. Even a small dose can disrupt the body's normal metabolic functions. But the ministry of environment and forests ( mef ), the ministry of health ( moh ), ministry of industry and the ministry of agriculture ( moa) are hardly concerned. Let alone take joint action to tackle the problem, most of their time is spent on passing the proverbial "buck".

Says S D Makhijani of the Central Pollution Control Board ( cpcb), which is under the mef , "There are so many industries in Delhi, it is difficult to keep a tab on all of them. We have neither enough staff nor funds to check them all."

Speaking for the moh, K L Radhakrishnan, secretary, Prevention and Food Adulteration ( pfa ), says, "Heavy metal contamination in food is definitely a problem but for reasons unknown, the moh has not taken it on its agenda." Adding fuel to the fire is A K Dikshit, senior scientist at the Indian Agricultural Research Institute, Delhi, under the aegis of the moa : "Even if heavy metals are present in agricultural products, it is not in our mandate to monitor them." So who is responsible for these metals anyway?

Heavy metals are a group of 19 elements which have many similar chemical and physical properties and are remarkably different from the remaining 97 known metals. Among the 19 heavy metals, lead, cadmium and mercury do not have any biological significance or beneficial use and are known to be extremely toxic. Other toxic metals of concern are chromium, copper, manganese, nickel, tin and zinc. Once dispersed in the biosphere, these metals cannot be recovered or degraded. Hence, environmental effects of metal pollution tend to be permanent (see chart: Heavy metals can reach anywhere! ).


1. Drinking water: Delhi
2. Leafy and non-leafy vegetables, Cereals, Pulses, Spices: Punjab, Rajasthan, Gujarat, Calcutta
3. Infant formula: 24 brands from Karanataka, Andhra Pradesh, Maharashtra
4. Cow and buffalo milk: Punjab
5. Cooked food: Rajasthan, Gujarat
6. Vanaspati-brands like Dalda, Sunflower, Chanda: Different manufacturers
7. Human blood: Delhi, Mumbai
8. Canned food-mango, pineapple, tomato, fish,
mutton: Different industries in India
9. Toys
10. Cigarettes: All brands
11. Holi colours: Delhi
12. Soil, water-surface and ground: Andhra Pradesh,
Uttar Pradesh
13. Air: Delhi, Calcutta
14. River-Ganga, Yamuna, Sutlej, Chambal, Brahmaputra, Godavari: Delhi, Punjab, Madhya Pradesh, Assam,
Andhra Pradesh

Where metals meet
Heavy metals are in the air we breathe, the food we eat and the water we drink

-- (Credit: Anand Singh Rawat) The environmental impact of heavy metals always goes unnoticed and is rarely catastrophic to merit immediate measures. Except for the recent report on arsenic poisoning in West Bengal, no major episode of metal toxicity has been recognised in India (see box: Arsenic poisoning ). It took decades of research to establish the cause and source of cadmium poisoning along the Jinzu river in Japan (see box: Brittle bones ). Besides, sophisticated equipment and rigorous controls of laboratory conditions are needed to analyse heavy metal impacts. Such facilities in India are either non-existent or are very inferior.

air : A human being breathes in 12,000 litres of air each day, yet keeps on using the atmosphere as a refuse bin. Approximately 734,000 tonnes of heavy metals are released into the atmosphere every year worldwide. According to N Manivasakam, of the Princial Public Health Laboratory in Coimbatore, the main sources of atmospheric metal pollution are mining, smelting and refining of metals; burning of fossil fuels; production and use of metallic commercial products; and, vehicular exhaust.

The available data for air concentrations for India reveal consistently higher values (see chart: Dirty air ) compared to the World Health Organisation ( who) standards. The data represents atmospheric concentrations in Ludhiana in Punjab.

water: Drinking is one of the key routes of intake of heavy metals by the human body. The who has laid down several guidelines for heavy metal content in drinking water. Yet, approximately 1,108, 000 tonnes of heavy metals are released into the water every year worldwide. The main sources of water pollution are domestic sewage and industrial effluents; power plants; and atmospheric fallout.

According to the National Environmental Engineering Research Institute ( neeri ), Nagpur, 70 per cent of India's inland water is unfit for consumption. All major rivers contain metals in excess of the prescribed limit (see chart: Watered down ).

A cpcb study reported that the river Yamuna, even before it reaches Delhi, contains a host of heavy metals. A glass of water from the Yamuna contains 0. 01 nanogramme/litre (n/l) of chromium, 0.01ng/l of cadmium, 0.02ng/l of nickel and 0.02ng/l of zinc, says Devika Nag, head of the department of neurology, King George Medical College, Lucknow.

The sewage treatment plants -- either obsolete or inadequate -- cannot get rid of the toxins. Of the country's 142 major cities, only eight have satisfactory sewerage systems, 62 have partial arrangements, while 72 cities have none.

soil : Besides air and water, approximately 6,209,000 tonnes of heavy metals enter the soil every year through agricultural and animal wastes; municipal and industrial sewage; coal ashes; fertilisers; discarded manufactured goods; and atmospheric fallout.

Soil contamination should be a primary concern as India relies heavily on agriculture. And all human beings, especially children, are in touch with soil. Agricultural lands in many industrial areas have already been rendered useless (see chart: Soiled earth ). Similarly, large-scale application of chemical fertilisers and pesticides has contaminated the soil with large amounts of metals such as cadmium, lead and zinc.

Dirty air


WHO Limit ng/m3 India
CADMIUM 10-20 330-21,000
LEAD 500-1,000 25-3,677
MANGANESE 1,000 27-3,259

Soil contamination should be a primary concern as India relies heavily on agriculture. And all human beings, especially children, are in touch with soil. Agricultural lands in many industrial areas have already been rendered useless (see chart: Soiled earth ). Similarly, large-scale application of chemical fertilisers and pesticides has contaminated the soil with large amounts of metals such as cadmium, lead and zinc.

Watered Down
Metal content in fresh water in Delhi, Mumbai
Heavy metal Limit for drinking water* (/gl)** Thane creck in Mumbai maximum (/gl) Yamuna at Wazirabad, Delhi (/gl)
LEAD 50 25,100 930
ZINC 5,000 93,600 280
CADMIUM 10 2,800 10
NICKEL - 14,500 -
CHROMIUM 50 - 1,770
MERCURY 1 435 1,850
IRON 300 40,300,000 330
MANGANESE 100 12,900 -

Use and throw
Indian industry depends extensively on heavy metals. Toxic emissions are but natural

-- Soon after Independence, India stepped into the second half of the 20th century with a spurt in the growth of heavy industries: industries that needed a large amount of heavy metals. Mining operations began on a large scale and mine wastes, sewers and belching chimneys pumped in large amounts of metals into the river channels and atmosphere.

Heavy metals are required either as catalysts or ingredients in the manufacturing process. They could also be part of the manufactured products. Among the industries with the highest emissions is the mining industry. Thermal power plants, chemicals and leather industries also contribute heavily to the heavy metal load.

mining and metallurgy : The Indian subcontinent is replete with minerals and almost every state has its own coal or metal reserves where mining is extensive. Most of these areas are regarded as heavy metal "hot spots" where extraction, processing and use of the metals are intense (see box: Hotter than hell ).

India is the fifth largest producer of coal. But this distinction is not without its disadvantages. Mining releases chromium, cadmium, lead and mercury -- all toxic heavy metals. Raniganj in West Bengal, Jharia in Bihar and Singrauli in Madhya Pradesh are considered some of the "hot spots" of metal pollution (see map: Coal galore ).

Other metals mined in India include lead, zinc, nickel, chromium, copper, iron, manganese and tin. About 20 per cent of released cadmium, a potent carcinogen, comes from zinc mining and smelting operations. Today, Bichhri in Rajasthan has no fertile land left for agriculture. It is hard to find clean water for drinking or irrigation. Hindustan Zinc Limited, a public sector undertaking, and several other smaller private industries, have contaminated the entire village with zinc and cadmium. Several other mines -- Khetri and Zawar in Rajasthan, and Malanjikhand in Madhya Pradesh, for instance -- have reduced the adjoining areas to virtual wastelands.

thermal power plants : Yet another source of heavy metal pollution is thermal power plants. At present, India has 80 of these. A 2,000 megawatt (mw) thermal power plant with an annual consumption of eight million tonnes of coal produces 1,600 tonnes of lead, 800 tonnes of zinc, 80 tonnes of cadmium and 40 tonnes of uranium. Needless to say, all these end up in the environment. For instance, the Talcher thermal power plant in Orissa pumps almost five tonnes of these harmful heavy metals every day.

In a paper presented at a health conference organised by the Centre for Science and Environment ( cse ) in July 1998, K C Sahu, former professor of the Indian Institute of Technology, Mumbai, reported that the annual toxic heavy metal load of the Yamuna from the two power plants in Delhi -- Rajghat and Indraprastha -- are estimated to be 2.6 tonnes of lead, 0.03 tonnes of cadmium, 4.32 tonnes of chromium and 1.98 tonnes of nickel. Other thermal power plants which pollute the environment are in Singrauli, Uttar Pradesh, Korba in Madhya Pradesh and Ramagudam in Andhra Pradesh (see map: Light zones ).

chemical firms : The Indian chemical industry has an annual turnover of approximately Rs 50,000 crore. These industries, which include agro-based industries manufacturing fertilisers and pesticides, use chlorine for different purposes. Using their current technology of production, heavy metals like cadmium, mercury, lead, zinc, nickel and chromium are released into the environment.

Gujarat and Maharashtra have some of the largest clusters of chemical industries over small areas.

leather tanneries : Tanneries also discharge huge amounts of chromium into the environment. There are about 2,500 tanneries in India. It was reported in the Indian Journal of Environmental Protection that the total wastewater discharge ranged from 80,000 to 1,00,000 cubic metres per day. About 90 per cent of these are in the small and medium scale sectors, and are not equipped with effluent treatment plants. Untreated tannery effluents contaminate the land, ground and surface water.

sugar firms and distilleries: India is the largest manufacturer of cane sugar in the world. But again, this distinction comes with a hefty price: ethanol. Molasses is a major byproduct of the sugar industry, which is again a raw material for the manufacture of industrial alcohol, ethanol.

In India, sugar is refined using sulphur dioxide, hence, the molasses and ethanol produced have a high sulphur content.

The heavy metal content of Indian molasses is also higher compared to that of beetroot-based molasses from other countries. According to Sahu, the concentration of iron and zinc in Indian molasses is 410 microgramme per gramme (g/g) and 477 g/g respectively, which is 10 to 30 times higher than that of Cuban or Brazilian molasses.

batteries: Out of the total amount of lead produced in the world, 70 per cent is used in the manufacture of lead batteries. Cadmium and nickel are also used in storage batteries. Pollution occurs from the time of manufacture and their use till the time they are either repaired or disposed off. At present, in India, a substantial number of discarded batteries are bought by small operators who are ill-equipped to handle these toxins. India has at least 36 battery-making units.

To tackle the battery menace, Germany has come up with a new law that mandates people to bring their discarded batteries to any store selling batteries or to the municipal points of collection, where these are accepted free of charge. Proper recycling of batteries is now enforced. Use of certain kinds of heavy metals in batteries is also banned.

electronic firms: The Indian information and technology ( it ) and computer hardware industry has an annual growth rate of 40 per cent per annum. Even after excluding the heavy metal content in batteries, various other heavy metals are used in the it industry, some of which are lead, tin, copper, cadmium and nickel. Although very few toxic metals are used in the making of a computer, their numbers are increasing so rapidly that recycling becomes an important issue. Moreover, many materials generated during manufacture cannot possibly be reused. For example, computer screens are made of large amounts of lead and it is cheaper to dump them than reuse them. All of this lead will finally enter the environment.

It is not only the environment which takes a beating. it workers are exposed to hundreds of toxins every day, making them vulnerable to diseases which arise from long-term toxin exposure. Multiple studies have shown that the rate of miscarriage among female employees handling toxic materials in the us for instance, is significantly higher than normal rates.

Poison in every bite
The content of tin in canned food increases by 7 to 15 times in one year

-- In India, very little attention has been given to the accumulation of heavy metals in food products though all edible food products such as vegetables, cereals and fruits are replete with these toxins.

A study conducted by cpcb and the department of agriculture, Calcutta University, which was reported in The Telegraph in July 25, 1997, shows that vegetables grown at Dhapa-Bamtala, a small locality in Calcutta, contain toxic metals. One-fourth of the vegetables sold in the city's markets comes from this area. Dhapa-grown cauliflower contains 44.1mg of lead and 3.3mg of cadmium in every kilogramme of produce. So if anyone has eaten 23 kg of Dhapa-grown cauliflowers, he or she has also ingested about one 1mg of lead and about 0.08mg of cadmium. The who standard of lead is 0.5 mg per kg of body weight per person and for cadmium it is 0.0083mg/kg.

Two studies conducted by the icmr in 1993 and 1996 also reveal that canned food products contain metals like lead, aluminium, tin and zinc. After storing the product for one year, the content of tin in canned food products kept at room temperature increased from 27 mg/kg to 542 mg/kg - almost 7 to 15 times more than when these products were canned.

The exposure of heavy metals to the human body can be either through ingestion, inhalation or skin. Infants and foetuses are exposed to metals through breast milk or trans-placental transfer (transfer of blood from the mother to the foetus). Heart and chronic lung diseases are some of the known effects of heavy metal pollution (see box: Lead story ).

Household goods
The use of heavy metals in household items has grown over the years. No one is spared here. From the walls to the floors, kitchen to the dining room, nothing is safe. Be it lead, mercury, cadmium or chromium, hardly any household item is safe from these toxic metals.

One of the social evils of Indian society is food adulte-ration, a practice commonly found in colouring of turmeric powder with lead chromate and use of non-permitted metal colours in food and beverages. And to think of it, turmeric is used to prepare every Indian meal.

At times, even dishes are not safe. Porcelain dinnerware is painted with pigments which contain lead, cadmium, chromium and cobalt. The us Food and Drug Administration has set limits on its use in European and Chinese porcelain tableware. In India, there are a number of small-scale industries, located all over the country, which make glazed ceramic potteries. And it is extremely difficult to keep a check on every one of them. But, at least, the public should be made aware that foods with high acid content should not be stored in ceramics and old ceramicware should never be used to serve food.

Then there are the plastic bags, widely used to carry vegetables and other food stuffs, including milk and cheese. Ingredients of the colours used in these bags are generally lead and cadmium. When fatty food materials are packed inside, there is a chance of food absorbing the paint.

Paints also contain varying amounts of lead. Every house is a myriad of colours. You can choose the colour, but not the contents. The cheaper the paint, higher the lead content. For instance, very high amounts of lead is used in the making of Ganesha and Durga idols. And when these are immersed into rivers or seas after the festivals, they contribute substantially to the high lead content in the water. Festivals bring with them heavy metal exposure. The festival of colours, Holi, besides excitement brings along with it a fair share of toxic pollutants. These colours contain lead and mercury. Both these metals reach the blood stream directly through the skin, says Amit Nair, environmental toxicologist of cse .

Then there are the plastic toys, a child's best friend. These toys contain hazardous levels of lead and cadmium. An independent laboratory analysis has revealed that some of the toys, even from reputed companies, release toxic metal dust to their surfaces. It was reported in the Multinational Monitor in 1997 that lead or cadmium contaminated dust is hazardous since it can enter the body by licking, chewing or inhalation. As the toys get older, more of the metal dust is liberated.

Killing Fields
Heavy metals cause a number of distress
LEAD Mining, coal, automobile,paper, dyeing,petrochemicals, etc. Learning disability;mental retardation
CHROMIUM Leather/tannery, thermal power plants, mining fertilisers, textile, photography Bronchial asthma, allergies,
CADMIUM Coal, nuclear and coal power plants,batteries, ceramics, toys Itai Itai disease (fragile bones)
NICKEL Mining, coal power plants,phosphate fertiliser,  chocolate, automobile,    electroplating Dermatitis, pneumonia
MERCURY Mining, paper and pulp, coal power plants, cement, pesticides, cosmetics Minimata disease (disorder of the nervous system)
ZINC Phosphate fertilisers, distillery,pharmaceuticals Fever
IRON Coal mining, Skin becomes sensitive to light



Where do we stand?
Study on heavy metal toxicity is long overdue in India. But authorities concerned are yet to open their eyes to the health effects, let alone act

 There are no standards for me There are clear indications that toxic heavy metals in the environment have increased to harmful levels. But though the extreme toxicity of heavy metals have been scientifically established, there are several who still differ in their opinion on the effects of pollution. S D Makhijani, senior scientist at cpcb, says heavy metal contamination is not yet a problem in India. While M L Jain, head of environmental science, Nuclear Research Laboratory, iari, says most of the heavy metals monitored are below the permissible levels. Various studies in India do not show this to be true. But even if these scientists and officials are correct, should we wake up only when heavy metals start claiming lives?

The mef and moh are responsible for regulation of heavy metal pollution. The cpcb , which is under the mef , is the authority in the field of environmental pollution in India. It sets standards for effluents and emissions for industries and entrusts the state pollution control boards to enforce these. Under the moh are four Central Food Laboratories ( cfl ), in Mysore, Calcutta, Pune and Ghaziabad. The Mysore cfl is responsible for setting limits on heavy metals in food. Besides, there is the pfa Act, 1954, which provides tolerance limits for heavy metals in food articles.

But these standards do not work. Neither does research go smoothly in India. The work is totally compartmentalised and research organisations are not ready to share their findings with each other, says P S Dutta, principal scientist at the groundwater division of the Nuclear Research Laboratory, iari . "Instead of looking at the problem in a holistic manner, institutes like cpcb do not share results of their surveys and consider it as their personal property, despite reminders," he laments.

The pfa does not provide tolerance limits of many food articles. Of the 19 heavy metals, it has set limits only for seven. Infant milk formula, the only diet for infants, has no specific limits for any metal. According to K L Radhakrishnan, secretary of pfa , the Central Committee for Food Standard sets the limits of heavy metals in food items. "But the last meeting was held in 1996 and unless another meeting is scheduled, nothing can be done."

Interestingly, the ministry of food and civil supplies, which is responsible for the quality control of canned fruit does not follow the pfa limits. Instead, it follows the limits set by the Fruit Products Order, 1955, whose limits are higher than the pfa . These are only a few glaring examples of the incoherence in the working of the designated authorities.

So far, the government has only advocated cleaner, healthier and better environment, but has actually done precious little to achieve the goal. Besides lacking in their initiative to launch a clean-up drive, the bureaucrats, who decide the research and its funding, "are unaware of the heavy metal problem in the country," say scientists at the soil science division, iari . "And they decide the projects which the government should undertake."

What can be done?
"We seek to enhance the quality of our environment by mastering the science of metallurgy and materials technology but, in the process, we jeopardise the quality of our own life by exposing ourselves to heavy metal pollution," says S A Abbasi, director, Centre for Pollution Control and Energy Technology, Pondicherry. And that is exactly what is happening.

The only way to minimise the heavy metals threat is to limit their use. For the long-term planning, the less we excavate the earth for minerals, the better. Substituting minerals with natural products, composites and non-toxic metals is another option. But even while considering such alternatives, the pollution prevention option must be considered. Popular practices like metal coating and colouration of food should also be banned and food additives strictly certified.

A multi-disciplinary approach is necessary for critical sample collection, assured quality analysis, interpretation of laboratory and epidemiological data and surveillance. As far as possible, monitoring and surveillance should be maintained in the "hot spots" of metal contamination. There is also an urgent need to establish standards of heavy metal levels in air, soil, water and living beings.

No industrial effluents or sewage should be allowed to be discharged into rivers or natural bodies without prior treatment and no metal-polluting industry be permitted in food-growing belts. Ecological tax reforms should also be introduced. Toxic products should be taxed and industries responsible for the heavy metal load in the environment should be fined.

It is not a question of whether heavy metal contamination is a problem, but whether we should act before it is too late. Enough of this conspiracy of silence!

Based on papers by Amit Nair, environmental toxicologist at CSE, and K C Sahu, former professor at IIT, Mumbai



Subscribe to Weekly Newsletter :
Scroll To Top