As modern man's dependence on chemicals for societal benefits has grown, the potential for widespread pollution or contamination has also increased. There are now some 70,000 chemicals on the commercial market, and many of these are currently used and released into the environment with little or no knowledge of their potential long-range effects. It is estimated that 1,000 new chemical enter the market each year. There are five potential sources of pollution from chemicals: (a) Chemical products themselves, such as CFCs, pesticides and nitrate fertilizers; (b) Hazardous waste and its treatment; (c) Chemical emissions, such as from factories, power plants and automobiles; (d) Accidents, such as the fire in 1986 that destroyed a chemical store in Switzerland belonging to Sandoz; and (e) Transport of chemicals.
With the massive expansion in the availability and use of chemicals throughout the world, exposure to pesticides, heavy metals, small particulates and other substances poses an increasing threat to the health of humans and their environment. Pesticide use causes 3.5 to 5 million acute poisonings a year. Worldwide, 400 million tonnes of hazardous waste are generated each year. About 75 per cent of pesticide use and hazardous waste generation occurs in developed countries. Despite restrictions on toxic and persistent chemicals such as DDT, PCBs and dioxin in many developed countries, they are still manufactured for export and remain widely used in developing countries.