Complete information the Defining and characteristic of Hazardous Wastes



You know that living beings require food. They use food for their growth and development and for producing energy. In this process they also generate wastes. Industries also use raw "materials, process them to yield useful products and are left with wastes which may sometimes exceed 50 per cent of the raw materials used. This is quite inevitable, as industry increases in size and complexity. Natural ecosystems which can cope with the demand for food as. well as the disposal of the wastes, in the case of industries, the waste can go on accumulating unless properly disposed off. Some of this waste is hazardous in nature, and may need special care with regard to disposal.

Although hazardous waste chemicals make up to 15 per cent, of the total industrial wastes, their extremely dangerous nature requires that they be properly and carefully disposed off. If this waste is not judiciously disposed off, the natural resources can be seriously contaminated, posing a serious threat to the quality Of environment in general and human health in particular. Various methods of hazardous waste disposal have been described in this unit.

International consensus on a universally acceptable, comprehensive definition and system of classification of hazardous wastes has not been reached. One of the reasons for this disagreement is that suitable parameters of definition are difficult to identify. In this article, you will learn how to define the term hazardous wastes and distinguish it from toxic chemicals.

Waste is often a complex mixture that makes the analysis of its composition difficult and often a very costly exercise. Even if adequate analytical data are available, the significance of a particular waste component is seldom appreciated. What treatment a waste should undergo before disposal, and what are the after-effects of improperly disposed wastes in the long run. A special mention will be made about waste management in India.


Hazardous wastes are chemical by-products of an industry, a factory or a chemical plant. They may result from household activities or even from a hospital or a research laboratory. Armed conflicts, where nuclear or chemical weapons are used, also release enormous amounts of hazardous wastes. A chemical produced by any 01 the above sources which may endanger human health', pollute the environment or carry hidden risk to life if managed or disposed off improperly is called 'hazardous’. A waste is considered as hazardous if it has any one of the following characteristics:

  • Ignitability—catches fire easily,
  • Corrosiveness- -wears away other materials,
  • Reactivity—reacts strongly with water or explodes on reaction with other chemicals,
  • Radioactivity—releases ionizing radiations, and
  • Toxicity—produces symptoms of metabolic disorders, poisoning, disease, mutations, cancer or malformations.

Toxic Versus Hazardous

Generally, the terms "toxic" and "hazardous" are used interchangeably as if they were synonymous. But this is not tare. The former refers to intrinsic characteristics whereas the latter includes extrinsic characteristics also. "Toxic"—defines the capacity of a substance to produce injury after entering the metabolic processes of the consumer, an animal, a plant or a human being. The changes caused may either be pathogenic, mutagenic, teratogenic or carcinogenic.

The term 'hazardous' denotes the potential of a substance to pose threat to life or material through any one of properties mentioned above, namely, toxicity, ignitibility, corrosiveness, reactivity, explosiveness or radioactivity. The term "hazardous" is thus broader and includes "toxic" wastes in its spectrum.

You can see that some substances may be hazardous on more than one account. For example, benzene is toxic as well as ignitable; strong acids and alkalis from corrosive mixtures which sometimes explode if improperly handled.

Defining Hazardous Wastes

Recognizing the fact that the term "hazardous" implies both intrinsic and extrinsic properties, a complete definition of hazardous wastes should answer the following five questions :

  1. Hazardous to what?
  2. Hazardous to what degree?
  3. Hazardous for what reason?
  4. Hazardous at what time?
  5. Hazardous under what conditions?

Definition of Hazardous Waste

Answering the above questions, a complete definition of hazardous waste can be only as follows :

Hazardous waste means a waste, which because of its quantity, concentration or physical, chemical or biological characteristics may :

a) cause or significantly contribute to an increase in mortality or an increase in serious, irreversible or incapacitating reversible illness, or

b) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed.