Hazardous Wastes

Hazardous wastes are by-products of human activities that could cause substantial harm to human health or the environment if improperly managed. The United States Environmental Protection Agency (EPA) classifies liquid, solid, and gaseous discarded materials and emissions as hazardous if they are poisonous (toxic), flammable, corrosive, or chemically reactive at levels above specified safety thresholds. In the United States, the term hazardous waste generally refers to potentially dangerous or polluting chemical compounds; other potentially hazardous industrial, military, agricultural, and municipal byproducts, including biological contaminants and radioactive waste, are regulated by other government agencies than the EPA's hazardous waste division.

The handling of hazardous wastes became a major political issue in the late 1970s in the United States and other industrialized nations when a number of high-profile human health and environmental pollution crises focused public attention on the problem. Since then, many governments have greatly expanded regulation of hazardous waste management, disposal practices, and clean-up. In the United States, the EPA oversees hazardous waste regulations that attempt to prevent new cases of environmental and human contamination, as well as the so-called "Superfund" program that addresses clean-up of sites contaminated in the past.

Industrial hazardous wastes

Four types of industry account for about 90% of industrial hazardous wastes generated in the United States: chemical manufacturing, primary metal production, metal fabrication, and petroleum processing. Large chemical plants and petroleum refineries, and other "large quantity generators" that produce more than 2,200 lb (1,000 kg) of hazardous wastes per month, are the most visible and heavily regulated facilities in the United States. However, businesses of all sizes generate dangerous chemicals; the EPA currently lists more than 250,000 facilities as "small-quantity generators" of hazardous waste. These diverse, smaller producers account for about 10% of the potentially harmful substances produced each year.

Pesticides like malathion, DDT, and diazanon are hazardous chemicals; some of them have been banned, but many are still manufactured and used in the United States. Pesticides are designed to kill pest insects, plants, and other organisms that threaten agricultural crops, destroy municipal and residential landscaping, and carry human diseases. Most pesticides are dangerous chemicals themselves, and their manufacture produces additional hazardous waste. The EPA's Hazardous Waste division regulates handling, disposal, and clean-up of pesticides during their production, but environmental pollution and human health effects caused by pesticides after application are not included in hazardous waste regulations. (The EPA's Office of Pesticide Programs oversees pesticide use and handles cases where pesticides in agricultural or landscaping runoff pollute air and water or compromise human health.)

Other sources

Other types of hazardous wastes are associated with military bases, mines, residential communities, and small businesses. Though large industry produces the majority of hazardous waste in the United States, the small quantity generators (SQGs) that produce between 220 and 2,200 lbs (100–1,000 kg) of hazardous waste per month present particular regulatory challenges: (1) The chemicals used by auto garages, dry cleaners, construction companies, scientific labs, photo developers, printers, large offices, and farmers are often toxic. (2) Hazardous wastes generated by SQGs are much more varied than those produced by large companies. Each chemical, be it a month's supply of dry cleaning fluid or a house-worth of residential insulation, requires its own handling and disposal strategy. (3) SQGs, who do not have the legal and administrative support common at large companies, often have difficulty deciphering hazardous waste regulations. Noncompliance can result from simple ignorance of a small business's responsibility to follow environmental laws.

United States military bases have some of the most serious hazardous waste problems in the nation, an issue only recently addressed by government and private environmental agencies. About 19,000 sites at 1,800 military installations show some degree of soil or groundwater pollution. More than 90 military bases have been on the EPA's Superfund list of high-priority, hazardous waste cleanup sites. Moreover, a law passed in 1992 allows federal and state regulatory agencies to levy fines against the military if their hazardous wastes are not properly managed. Prior to this, the armed forces were not subject to state or federal environmental laws. Consequently, the military now has a range of programs to clean up hazardous waste problems at its bases.

Mining waste, a type of industrial waste, often includes hazardous substances. Mining operations commonly use hazardous chemicals, and sometimes naturally toxic substances are released into the environment during mining and the disposal of its waste materials. For example, gold mining in the Amazon Basin of South America results in the release of 90–120 tons of mercury into rivers every year. This has resulted in elevated levels of mercury in fish and humans in the region. Mercury poisoning results in severe birth defects, neurological disorders, kidney failure, and a number of other serious health effects. Chemical separation of ore minerals like lead, iron, and zinc from their host rocks creates socalled acid-mine drainage that contains both the toxic chemicals used in the separation process like arsenic and sulfuric acid, and poisonous heavy metals like lead and mercury. Acid-mine drainage from metal mining in the American West has contaminated drinking water and caused serious ecological damage since the mid-1800s.

Household hazardous wastes are discarded products used in the home, which contain dangerous substances. Examples include paint, motor oil, antifreeze, drain cleaner, and pesticides. In the 1980s, many local governments in the North America began to set up regular collection programs for household hazardous wastes, to ensure that they are properly disposed or recycled. Local or state/provincial governments usually pay the costs of such programs. However, a system used in British Columbia, Canada, requires consumers to pay an "eco-fee" on paint they buy. This, along with funds provided by the paint industry, helps pay for a collection program for waste paint from households.