As the amount of hazardous waste produced increases annually, places and methods of disposal that are scientifically, technologically, politically and environmentally safe are becoming more difficult both to discover and to agree upon. Many alarming events in the past decade have resulted from indiscriminate dumping of wastes. Wastes have been considered to be worthless, and so there has been little economic incentive to recover them, and, instead, considerable desire to dump them as quickly and cheaply as possible. But improper disposal may render a relatively harmless substance dangerous.
There are laws to control the use of the thousands of new chemicals put on the market each year, but there is little regulation over disposal. By-products and intermediate chemicals, created during the manufacturing process, usually end up in the wastes; these may be more chemically and biologically active than the finished products, and thus potentially more harmful in the environment. The notification schemes recently brought in by law do not cover wastes; their potential damage may go unrecognized. It is also physically difficult to screen wastes for toxicity because they are highly complicated mixtures of substances. If these wastes are exported for disposal or used for other purposes, they may do serious damage because people are unaware of the risks. Particularly vulnerable are the developing countries, because of relatively cheap prices, few environmental regulations, few people trained in necessary technology, corruption and poverty. In highly industrialized countries fragmented waste treatment laws, overlapping enforcement agencies and too few inspectors means that a significant amount of toxic waste is improperly treated.
Hazardous waste is about 10-20% of the world's manufacturing waste. Tens of millions of tonnes of toxic and otherwise hazardous substances enter the environment every year as unwanted wastes. The managing and disposing of this waste is a significant problem. Until recently, many hazardous wastes were disposed of without proper evaluation of the environmental consequences. There have been several hundred cases of contamination of wells by poisons from hazardous wastes - the most common of all the dangers to arise from improper waste disposal. These often occurred because the wastes were put into sand or gravel pits or old mine workings.
The USA generates 60 million tons of hazardous wastes a year; the EEC/EU generates approximately 20 to 30 million tonnes.