Man and his environment

The long and tortuous evolution of the human race in the planet has reached a stage, when through the rapid growth of science and technology, he had acquired the power to transform his environment in countless ways. Both aspects of the environment, natural and man-made, is essential to well-being of man and to the enjoyment of basic human right-even the right to life itself.

The protection and improvement of the human environment is a major issue which affects the well being of people and economic development throughout the world. It is the urgent need of the people of the world and duty of all government.

We see the growing evidence of man-made harm in many regions of the world. Dangerous levels of pollution in water, air, earth and living beings, major , undesirable disturbances to the ecological balance of the bioshpere, Tsunamis, hurricane, storms and earthquakes. There is destruction and depletion of irreplaceable resources, and gross deficiencies harmful to the physical, mental and social health of man.

In the developing countries most of the environmental problems are caused by under-development. Millions live far below the minimum levels required for a decent human existence, and are deprived of adequate food, clothing, shelter, education, health and sanitation. The developing countries must put effort to development ,bearing in mind their priorities and also must safeguard and improve their environment. At the same time, the industrialised countries, should make efforts to reduce the gap between themselves and the developing countries. The environmental problems in industrialise countries are generally related to industrialization and technological development.

The continuous population growth also presents problem on the preservation of the environment.

For the purpose of attaining freedom of nature, man must use knowledge to build, in collaboration with nature, a better environment. To achieve this it will take acceptance and responsibility of citizens and communities and enterprises and institutions at every level, all sharing equitably in common efforts. Local and national governments should bear the burden of large-scale environmental policy and action within their jurisdiction.International cooperation is needed to raise resources to support the developing countries in carrying out their responsibilities in this field.

Risk assessment for the hazardous waste management

Risk assessment is done to make the characterization of the potential adverse effects of human exposure, to environmental hazards. It is a tool for understanding the health and environmental hazards associated with hazardous waste and can improve the basis upon which to make such waste management decisions.

Risk may be defined as the probability of suffering harm or loss when the resulting harm is measurable. The hazard posed by a waste is a function of it' s toxicity, mobility ,it's persistence and also how it is contained. The human health risk assessment includes carcinogenic and non-carcinogenic risks to all receptors exposed to hazardous chemicals of the environment.

The introduction of chemicals into an ecosystem can provide a direct hazard to individual organisms, or may affect their ability to reproduce. It can affect the overall structure and function of an ecosystem or it's components.

Potentially exposed population should be considered in management of waste-:

Present and future population in vicinity of the site .
Sub-population of special concern e.g.young children in the case of lead contamination.
Potential on-site workers during any redemption.
What sort of sensitive public facilities are located near the site e.g. schools, hospitals, day care centre, nursing homes etc.
What outdoor activities occur e.g. parks, play ground etc.
What fraction of time do various sub-population spend in potentially contaminated area e.g. children in grade school.
What secondary exposures are possible e.g. contamination of crops at nearby farm.

Treatment methods for hazardous wastes include biological treatment, neutralization, oxidation-reduction, precipitation, carbon absorption, ion exchange, reverse osmosis, fixation/stabilization, and incineration.

After various treatment method ,there will always remain some residue to be disposed off. Land disposal techniques include landfills , surface impoundment's underground injection wells, and waste piles. Wastes should not be mixed.The location of each cell of different wastes should be clearly identified in a locator map or similar means. Surface impounments are excavated to store liquid hazard waste. Injection wells are used as a cheap method of disposing hazardous waste; They should be located well below drinking water aquifers.Unless these wastes are innocuous before disposal, they are like time bombs waiting to explode at the right moment.

Waste piles are non-containerized accumulation of solid wastes used for temporary storage. Research must be made to find economical ways that will render hazardous waste harmless before being put in their final resting place.