ENVIRONMENTAL HEAVY METALS AND MENTAL DISORDERS OF CHILDREN IN DEVELOPING COUNTRIES

摘要

Environmental pollution is a product of urbanization and technology, and other attendant factors of population density, industrialization and mechaniz-ation that serve to provide the necessities of the population. For example, in cities of developing countries, the rural-urban migration activated by the search for increased incomes has resulted in the concentration of large populations in relatively small areas under poor conditions of sanitation. Traffic jams and the legendary `go-slow' of automobiles are everyday occurrences in these cities. The impact of pollution in the vicinity of overcrowded cities and from industrial effluents and automobile exhausts has reached a disturbing magnitude and is arousing public awareness. At present, no enough data are available on the extent of environmental pollution because there are no agencies charged with the routine monitoring and protection of the environment. This chapter there-fore focuses on the critical issues of heavy metals (HMs) pollution in rapidly developing nations. Once emitted from their sources, they have the property of accumulating in the environment for many years. They enter the human body through inhalation, ingestion, and dermal. They also can accumulate in the bodies of animals and humans before they even cause damage. However; HMs such as Lead (Pb), Cadmium (Cd), Arsenic (As), Manganese (Mn) Nickel (Ni), Chromium (Cr) and Mercury (Hg), are also metabolized in the body in a similar way to nutrient metals. Environmental exposure to HMs can occur through air, soil, drinking water and food stuff. The neurotoxic effects of exposure HMs in the environment, though insufficiently recognized, remains a topic of sub-stantial current concern and interest as it could be considered an early endpoint for health effects induced by exposure to heavy metals. In addition, they can adversely affect the quality of life, and have broad health, social and economic implications. Special concern is directed to children as they are the most sensitive population exposed to environmental pollution in general and heavy metals in specific. Finally, the magnitude and potential severity of neurotoxicity problems make it imperative to direct researches towards preventive intervention, and focus on the development of new biomarkers for neurotoxicity at the individual and population levels with emphasis on health education about HMs exposure and their potential for neurotoxicity. The establishment of comprehensive monitoring systems and information gathering should be given priority by governments of the developing countries in the sub-region with support and encouragement from international agencies.