India is the developing country and due to industrialization and modernization, is leaving powerful impact at the global level on technical ground. But everything comes with pros and cons. Development at the sake of environment is not justifiable and is costing the threat to human as well as animal life, resulting in accumulation of heavy toxic chemicals, metals in the food chain as well as the water sources and air. It is discussed globally that environmental pollution in developing countries is mostly because of negative effect of technological developments like rapid urbanization and industrialization, with poor planning in waste disposal and management. Burning of fossil fuel, mining and metallurgy, industries and transport sectors are contributing toxic heavy metals into the environment, which persist for a considerably longer period and are resulting in bioaccumulation in crops.
Heavy metal toxicity is one of the major current environmental health problem and is dangerous because of bio accumulation through food chain. Heavy metal content in the vegetation around urban industrial areas has been found to be higher as compared to normal ones, indicating relationship between industrialization and environmental deterioration. Food of plant origin as well as animal origin like milk, meat has bio-accumulated these toxic metals and is the challenge to public health safety. Soil naturally has various heavy metals like Cr, Cu, Cd, Co and Pb etc but indiscriminate use of chemical fertilizers, insecticides, contaminated ground water is main reason for bio magnification of heavy metals in soil. Various heavy metals like Co, Cr and Cu are essential for plant and animal metabolism, but not at levels above maximum permissible limits (MPL). Above MPL, they disrupts the normal functioning of organisms. Metals like Cd, Hg and Pb are considered to be highly toxic and carcinogenic for humans and animals. Heavy metals of industrial biowaste contaminate drinking water, food and air. Heavy metals level above MPL effect hormone system and growth of different body tissues. Various types of cancer, rising infertility among men and women, foetal abnormalities are somehow linked to the excess heavy metal in the food chain, water. Heavy metal toxicity can be acute or chronic and worrisome fact is that the harmful effects of these metals, passed on from one generation to the next. According to a report by WHO (1995), about five million people die of diseases caused by drinking impure water and the incidence of water pollution from heavy metals has reached such an alarming level that environmentalists are finding it difficult to enforce effective control measures.
Scenario in India : In India various studies has been conducted to estimate the level of toxic heavy metals in water, food etc and their harmful effects on the population. Untreated sewage water of Musi river near Hyderabad was collected from different sites and it was found contaminated with Cd, Cr, Ni, Pb, Co, Zn, Cu, Fe and Mn. Most of the water bodies are used for irrigation of consumable aquatic plants in Lucknow, UP but it is alarming fact that the water used was found to be contaminated with a variety of toxic metals like Fe, Cu, Cr, Mn and Pb and the concentrations of Cr, Pb and Fe in the water were much higher than the recommended permissible limits by WHO. It is established by various researches that soils under sewage water irrigation had higher concentrations of Zn, Cu, Pb and Cd as compared to fields irrigated by underground water. Heavy metal contamination is also detected in milk and dairy products especially Pb. Concentration of lead (1.13 ppm) in milk of buffaloes reared in polluted areas of Delhi was found to be much higher as compared to milk of buffaloes reared from rural areas ( 0.24 ppm). It is also established that the concentration of Pb and other toxic metals is found to be more in milk samples from cows grazing on the busy roads as compared to agricultural areas and this indicates towards the need of improvement in farm practices also.
Scenario in Punjab : Punjab is known as the bread basket and granary of India and during the past few years, it has also become the industrial hub of India. Green revolution has made Punjab, the leading agricultural state but use of fertilizers, insecticides and pesticides has deteriorate the environment to major extent. With the entrance of many industrial projects to Punjab and lack of proper industrial effluents disposal system, the problem of environmental safety rises to the new level. Malwa belt of Punjab is becoming the home of cancer and it is assumed that establishment of Thermal power plants and other industries are the contributing factors. Fly ash from the burning of coals at these plants contains high level of uranium and ash, resulting in contamination of soil and ground water. This matter of uranium and other heavy metals beyond MPL in ground water in Bathinda, Amritsar district of Punjab was first highlighted by Guru Nanak Dev University (GNDU) in 1995. Samples collected in the close proximity around the thermal plants contains 15 times more Uranium above the WHO permissible safe limit. Uranium and other heavy metals like chromium, arsenic are also found in the Budha Nallah, the rivulet which merges into Satluj river in Ludhiana.In the year 2009, Uranium toxicity raises the concerns of everybody, when hair and urine samples of children, effected with birth abnormalities, neurological and mental disorders were collected in Faridkot district and on evaluation,Uranium above the safe limit was found in 88% of samples collected. This analysis came with the conclusion that increasing birth abnormalities, cancers, increasing Down Syndrome cases are because of High level of uranium. However the conflict of opinions still continues that whether or not Uranium toxicity is causing child abnormalities, neurological disorders and cancers as Government is stating these abnormalities because of genetic disorders. Also another panel of researchers claims the geological reasons for the Uranium contamination in water supply of Punjab due to Shiwalik sediments Uranium enrichments. So it has now become the need of the hour to ensure the actual causes of increasing cancers and other abnormalities, which were very rare during the past times.
Lead toxicity has also been reported in bovine in industrial area in Punjab. Level of Pb in the blood of animals were found to be higher (19.5 -73.1 ppm) than the normal level of 5-22.5 µg/100 ml of blood. The positive association between milk Pb level in cows and animal reared in areas around different industrial localities like Zn smelter, Al processing unit and steel manufacturing plant has been established. This indicates the entry of toxic metals in milk and milk is considered as one of the basic staple food for infants.
Some steps to mitigate the problem :