Hazardous wastes are solid, liquid, or gas wastes that may be deadly or harmful to people or the environment and tend to be persistent or Nondegradable in nature. Such wastes            include toxic chemicals and flammable or radioactive substances, including industrial wastes from chemical plants or nuclear reactors, agricultural wastes such as pesticides and fertilizers, medical wastes, and household hazardous wastes such as toxic paints and solvents.

About 400 million metric tons of hazardous wastes are generated each year. The United States alone produces 240 million metric tons—70 percent from the chemical industry. The use, storage, transportation, and disposal of these substances pose serious environmental and health risks. Even brief exposure to some of these materials can cause cancer, birth defects, nervous system disorders, and death. Large-scale releases of hazardous materials may cause thousands of deaths and contaminate air, water, and soil for many years. The world’s worst nuclear reactor accident took place near Chernobyl’, Ukraine, in 1986 (see Chernobyl’ Accident). The accident killed at least 31 people, forced the evacuation of over 100,000 more, and sent a plume of radioactive material into the atmosphere that contaminated areas as far away as Norway and the United Kingdom.

Until the Minamata Bay contamination was discovered in Japan in the 1960s and 70s, most hazardous wastes were legally dumped in solid waste landfills, buried, or dumped into lakes, rivers, and oceans. Legal regulations now restrict how such materials may be used or disposed, but such laws are difficult to enforce and often contested by industry. It is not uncommon for industrial firms in developed countries to pay poorer countries to accept shipments of solid and hazardous wastes, a practice that has become known as the waste trade. Moreover, cleaning up the careless dumping of the mid-20th century is costing billions of dollars and progressing very slowly, if at all. The United States has an estimated 10,000 abandoned hazardous waste dumps that need immediate action. Cleaning them up could take 50 years and cost $100 billion.