Depending on the nature of the pollutants the impact of industrial activities on the environment can have public health implications at a local, regional or even a global level. Various environmental and occupational factors of a physical, chemical, biological or psychosocial nature have the potential to induce different types of pathological processes.
Diseases caused by chemicals have been observed in most organ systems after high exposures such as those encountered occupational settings, including allergic reactions of the skin and of the respiratory tract and different chronic lung diseases. Other diseases include those of the kidney, the central nervous system, the cardiovascular system, the blood forming organs, the reproductive organs, the eye, and the liver and malignant diseases of different organs.
As manifestation of diseases associated with environmental factors are non-specific, it is usually very difficult to determine the extent to which exposure to environmental agents contributes to human disease and health impairment. This is because the etiology of most diseases is multifactorial. There is increasing evidence that some environmental factors may interfere with the resistance of the body, thereby increasing susceptibility to disease.
The followings are the summary of major industrial sectors which provide a description of processes intermediates, products, and health risks to workers and the effects on the health of the general population.
(1) Asbestos and Man-Made Fibers:
The industrial process of the extraction processing and melting of asbestos can lead to environmental exposure as can the breakdown of asbestos building materials in the indoor environment. Environmental exposures and effluent exposures from material in drinking water near mines have been linked with health effects ''"lading asbestos is pleural disease and cancer. Exposure of workers and the general population may also occur a result of demolition of asbestos containing buildings or the removal of asbestos from existing buildings.
(2) Basic Chemicals:
There are two classes of basic chemicals, organic and inorganic. Organic chemical production is based on petroleum and natural gas. Plastic and synthetic rubbers are major examples of organic chemicals; acids, alkalis and gases are example of inorganic chemicals. The development of skin and lung diseases, cancers of different organs and neurological effects as a result of exposure to such chemicals are of particular concern. Methyl mercury oxidation due to ingestion of fish contaminated with mercury from chemical industry waste was responsible for the neurological and tetragonal effects.
(3) Cement, Glass and Ceramics:
The major exposure in the cement, glass and ceramics industries is dust which may cause respiratory tract diseases including silicosis amongst workers. Chronic bronchitis and emphysema are frequent complaints. Other pollutants of concern are sculpture dioxide, carbon-monoxide, lead and fluoride. Elevated blood lead levels in the children and other family members of workers in the ceramics industries have been reported as a result of lead dust. *
A wide range of metals, acids and solvents and other toxics potential are used in the electronics industries, particularly in the manufacture of semi conductors. These have caused skin problems, reproductive disturbances and cancer. Leakage from storage tanks into the drinking water in neighboring communities has caused concern. Effluent chlorofluorocarbons from the industry contribute to ozone depletion and hence increased skin cancer incidence occurs.
(5) Iron and Steel:
Workers in iron and steel metals and foundries and in coke production are exposed to a great variety of potentially dangerous chemicals such as various metals, carbon monoxide, polycyclic aromatic hydrocarbons, benzene, heterocyclic aromatics, nitrogen oxides and sculpture dioxide. An elevated incidence of lung cancer has been demonstrated among workers in coke production and in iron and steel foundries.
(6) Rubber and Plastic Products:
The manufacture of these products involves large quantities of potentially hazardous organic and inorganic liquids and solids. Many of which have been associated with impaired worker health, including cancer, central nervous system effects, systemic poisoning and hearing loss. Solvents used in large volume are a particular problem.
(7) Metal Products:
Metals are processed in the heavy and light engineering industries to produce goods ranging from heavy machines and tools to metal components of consumer goods. Processes included casting, pressing, machining, welding, grinding, chemical treatment, plating, finishing, assembly and many others. Major health effects include physical injury, loss of hearing, heat and stress related disorders, respiratory diseases, solvent poisoning and cancer.
(8) Mining of Metals and Minerals:
The leaching of toxic minerals from mine tailings into the ground water represents a health hazard to the surrounding population. Miners may carry mine dusts from the mine on their clothes causing potential exposures for family and neighbors.
(9) Non-ferrous Metals:
The major health hazard in the non-ferrous industries is produced by the fumes and dust of various metals such as lead, mercury, cadmium and arsenic which may cause bronchitis, irritation and pulmonary edema amongst workers. Pulmonary function abnormalities have been noted in children living in the proximity of an aluminum smelter.
(10) Pesticides, Paint and Pharmaceuticals:
All these industries produce chemicals with proven hazard in the workplace. Because pesticides are designed for use in the general environment, the potential for hazardous exposures of the population is high. Potent environmental and health protection problems include the dangers of infection, toxic effects, allergies or other biological effects from the newly synthesized product and the dangers of accidental releases.
(11) Petroleum Products:
The industries associated with petroleum products provide a rich variety of air and water pollutants and hazardous wastes. Frequently emitted pollutants include hydrogen supplied, polycyclic aromatic hydrocarbons, CO, vinyl chloride, styrene, toluene, and benzene among others. Residents living in the vicinity of natural gas refineries have been shown to have significant increases in respiratory system symptom due to their exposures to sulphurdioxide and hydrogen supplied emission.
(12) Pulp and Paper:
With its many noxious emissions the pulp and paper industry does pose a risk for the general population. Complaints of acrid odor, headache, nausea, burning eyes and throat are very common. The major potential risks for the population living around these industries are the irritating gaseous emissions, e.g. sulphurdioxide, hydrogen supplied and chlorine compounds.
(13) Textile and leather:
The textile industry includes the preparation of cloth using natural or artificial fibres or both for mixing, spinning, weaving, knitting and finishing. Health's effects include noise induced hearing loss, chronic bronchitis, dermatitis and cancer of the lung, skin and bladder. Effects on the health of the general population arise from dust laden air, noise, waste and volatile organic emission.
(14) Wood and Furniture:
Major sources of exposure in the wood industries include wood and microbial dusts, glues and adhesives, as well as paints, lacquers and varnishes. High concentration of cholera- phenols and chlorinated phenoxyphenols has been found in ground water near saw mills. Burning of chlorophenol treated wood also contributes chlorinated organic toxins to air pollution.
From the year 1900, the estimated world population (1500 million) has reached 5300 million in 1990. Compared to the situation in 1990, there will be an extra 1900 million people (a rise of 36%) by the year 2010.
Progressive urbanization is continuing throughout the world. By the year 2010, the urban population of the world will exceed 9000 million - a rise of 70% compared with 2390 million city dwellers in 1990. The urban population of developing countries will double in the twenty years from 1990. I.e. more than 4 fold increase since 1970. Thus by 2010, more than half of the world's population will be city dwellers. Table - 7 summarizes the trend of urbanization. The rapid and excessive urbanization is the growth and size of the mega cities.
Since the dawn of civilization, cities have produced many beneficial effects for health and quality of life. Although high quality technology and organized health sources may exist in the city, many poor people may not have access to them and the child mortality, rates from diarrheal diseases, malnutrition and respiratory infection are far in excess of the average for the population.
In many countries, especially in developing ones, the pace or urbanization has been too rapid and the rate of economic growth insufficient to provide the basic urban services. Such developments have overwhelmed existing services and there has been a buildup of domestic and industrial wastes. This endangers an increasing hazard for both the natural environment surrounding the urban area and the health of the human population.
Uncontrolled industrialization has produced stack discharges and effluents that pollute the air and waterways and surrounding the land with waste products constituting toxic hazards for the natural flora and fauna and for human health. Domestic fuels and traffic exhausts produce indoor and outdoor air pollution.
As the intensity of traffic increases, the social environment deteriorates with a rising level of disturbing background noise. The cumulative impacts on the living environment and indirectly on human population of the physical, and chemical hazards associated with urbanization and industrialization are belatedly being identified.
Our estimate suggests that some 2.2 billion people live in the developing countries and nine out of ten of them have no access to safe drinking water, and one child in four is of low birth rate.
Serious aesthetic, environmental and health risks are associated with unsafe water supplies, inadequate sanitation, and ineffective waste management. The majority of morbidity and mortality in developing countries is caused by diseases transmitted by unclean water (infectious and parasitic diseases) and air borne contaminants (respiratory diseases).