Hazardous wastes are byproducts of human activities that can cause substantial harm to human health or the environment if improperly managed. The United States Environmental Protection Agency (EPA) classifies liquid, solid, and gaseous waste and emissions as hazardous if they are poisonous (toxic), flammable, corrosive, or chemically reactive at levels above specified safety thresholds. In the U.S., 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 government agencies other 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 highprofile 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 cleanup. In the U.S., 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.
Hazardous wastes can be solids, gases, liquids, or semi-liquids like mining sludge and drilling mud. Most of the wastes listed by the EPA are liquids or semi-liquids. Thousands of waste materials are considered hazardous. These include familiar substances such as used motor oil and mercury, agricultural pesticides, and industrial materials such as asbestos and poly-chlorinated biphenyls (PCBs). United States industries, farms, mines, military facilities, cities, and small businesses generate roughly 200 million tons of hazardous wastes each year. Furthermore, the EPA estimates that there are presently 6,500 facilities in the U.S. that require hazardous waste clean-up under the directives of the 1976 Resource Conservation and Reclamation Act (RCRA) and its 1984 Hazardous and Solid Waste Amendments (HSWA).
Hazardous waste management is also an international issue. Each year, industrialized nations with strict environmental regulations export more than
two million tons of hazardous waste for disposal in poorer developing nations with less stringent waste disposal oversight. Developed nations also locate large corporate, industrial, and military facilities in countries that have lax environmental restrictions.
Hazardous wastes often cause problems for years after their disposal. Many industrial waste disposal sites were established, filled, and buried long before establishment of present-day standards for management and disposal of hazardous chemicals. Toxic, flammable, corrosive, and reactive chemicals are often long-lived, and sometimes the dangers they posed to the environment and to human health were unknown at the time of their disposal. The companies responsible for many pre-1970 hazardous waste sites are no longer in business, and sometimes the sites themselves are difficult to locate. Even modern legislation gives industries fairly broad leeway to produce chemicals, police their own waste disposal practices, and to contest cases of possible environmental or human health damage. It is often difficult to prove a scientific link between an incident of drinking water poisoning, or a human disease cluster, and a facility that improperly handles industrial chemicals.
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 U.S. 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 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 cleanup 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 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 lb (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.
United States military bases have some of the most serious hazardous waste problems in the nation, an issue only recently addressed by 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. Before 1992, 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 so-called 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 North America began to set upregular 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 a 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.
Beginning in the 1970s, a number of highly-publicized hazardous waste crises and advances in environmental science led the American people and public health authorities to recognize hazardous wastes as a significant threat to health and the environment. Today, there is a public and political debate between those who believe that public perception of waste hazards is worse than the actual danger, and that adequate safeguards exist to protect people from significant exposures, and those who insist that government and industry need to do a better job of managing hazardous wastes, considering the harm that can be caused by these chemicals.
The case of chemical dumping by the Hooker Chemical Company at Love Canal in Niagara Falls, New York was a catalyst that dramatically increased public concern over hazardous wastes. The Love Canal community was built at the turn of the twentieth century as a residential subdivision centered on a small hydropower canal. The original developer never completed the canal, and the Hooker Company used the half-finished ditch as a dump for more than 20,000 tons of chemical wastes during the 1940s and 1950s. In 1953, the Hooker Company covered the dumpsite with soil and sold it to the town of Love Canal for a dollar. By 1976, residents and scientists had linked a series of public health problems including birth defects and childhood leukemia to teratogenic (birth defect-causing) and carcinogenic (cancer-causing) liquids, sludge, and gases seeping from the dumpsite.
The media reported extensively on the problems at Love Canal. The resulting wave of public outrage at television pictures of black sludge seeping from the ground, and children suffering from cancer, triggered a political response. In 1978, President Jimmy Carter declared Love Canal a federal disaster area. Two years later, the U.S. Congress passed so-called Superfund legislation, which established a national cleanup program for hazardous waste sites.
Activist groups such as Greenpeace and the Citizen’s Clearinghouse for Hazardous Wastes seek to increase public awareness of hazardous waste issues. Such groups frequently oppose government and industry policies and projects related to hazardous wastes. One outgrowth of the publicity surrounding hazardous waste is that it has become difficult to find locations for new treatment facilities because of local opposition. This is called the NIMBY, or “not in my backyard” syndrome. Civil rights groups in the United States have also called attention to the unequal distribution of hazardous waste dumpsites and handling facilities in poor and minority-dominated communities. Studies have shown that a disproportionately large fraction of African Americans and Hispanic Americans—three out of five—live in communities with hazardous waste sites.
A complex web of federal agencies and legislation oversee and regulate storage, transportation, disposal, recycling, and use of hazardous wastes in the United States. State and local governments also have hazardous waste regulations. The private environmental consulting industry helps government agencies, industrial manufacturers, cities, and businesses assess their hazardous waste practices and compliance with the increasingly long list of federal, state and local hazardous waste laws.
There are two main United States federal hazardous waste laws: the 1976 Resource Conservation and Recovery Act (RCRA), and the 1980 Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), also known as the Superfund law.
RCRA legislation focuses mainly on disposal of non-hazardous solid waste, and was enacted mainly to deal with unsightly garbage disposal practices. Hazardous waste disposal was a minor issue in the mid-1970s, but enough concern existed that Congress included a section on hazardous wastes in RCRA. Prior to the passage of RCRA, factories and plants typically dumped hazardous wastes in ponds, lagoons, or streams near their facilities. Many smaller waste generators sent their chemical by-products to outdated municipal landfills that where they leaked into ground and surface water reservoirs.
RCRA mandated creation of a system to track and monitor hazardous wastes from production to disposal, or from “cradle to grave.” Legislators also designed RCRA to regulate existing hazardous waste sites, and to improve hazardous waste management overall. RCRA’s goals have been partly accomplished, but problems have occurred along the way. For example, EPA has been slow to put some of the changes into effect. Some industrial polluters have discovered that it is less expensive to ignore the hazardous waste disposal recommendations, and to use their financial and legal resources to contest claims of environmental damage. Also, some of the legislation expected private industry to build expensive treatment facilities, hire environmental consultants to assess their practices, and to pay clean-up costs. In many cases, companies balked at the cost of self-regulation, and failed to meet the requirements. Community opposition to local siting also delayed or prevented construction of many waste treatment and disposal facilities.
The focus of RCRA has changed over the years. Amendments and enactment of related laws have moved the EPA’s focus from management and disposal practices to waste prevention. There is a growing consensus that it is less expensive, and much less dangerous to prevent a spill, leak, or poisoning than it is to clean one up. Regulations now encourage industries to produce fewer hazardous wastes, to produce wastes that are less hazardous, and to develop alternative methods that do not require dangerous materials.
In contrast to RCRA, which attempts to manage waste production, management, and treatment, CERCLA was designed to clean up sites that are already contaminated. The law established a National Priority List of the United States’ worst hazardous waste sites, and set up a fund, nicknamed Superfund, to augment remediation costs. CERCLA requires that the EPA, which enforces the law, try to find the parties, usually businesses or individuals, responsible for the hazardous waste problems, and make them pay for the cleanups. If responsible parties cannot be found, or if additional money is needed for a proper cleanup, then the governmental Superfund money may be used. The fund was started with $1.6 billion in 1980, and increased to $8.5 billion in 1986. Most of the money in the fund comes from a federal tax on chemical and petroleum companies, the industries responsible for many of the listed sites. Although the amount of money in the Superfund seems large, cleanup costs are high. The average cost to clean up a Superfund site is $30 million. There were 1,550 sites on the Superfund National Priority List in 2005.
The Superfund project and CERCLA have not been as effective as was initially hoped. Because of the technical difficulty, expense, and legal ramifications of cleanup, fewer than 100 sites have been completely cleaned up and removed from the National Priority List. CERCLA has also been widely criticized because of its liability provisions that require a potentially responsible party to pay cleanup costs. This party could, for example, be a business that transported waste materials to a dumpsite years ago, even if the site was not considered a problem at that time, and even if the company did not break any relevant laws. Because businesses often object to the CERCLA liability provisions, these matters frequently end up in court, slowing up the cleanup process.
Many developed nations have environmental regulations similar to RCRA and CERCLA. Some countries, Japan and Denmark for example, rely on partnerships of government and private industry to manage hazardous wastes. In both of these countries, industries receive subsidies or incentives to try new, innovative methods of handling their wastes. Ironically, the nations with the strictest environmental regulations end up exporting large quantities of hazardous wastes for recycling or disposal. Germany, for example, exported more than 500,000 tons of hazardous wastes to other countries each year in the 1980s. Non-governmental environmental groups have campaigned against the export of hazardous wastes by industrialized countries. The United Nation Environment Programme’s (UNEP) 1989 Basel Convention attempts to restrict international transport of hazardous wastes and to encourage less developed nations to resist the economic temptation to take hazardous waste from developed nations. In 2002, 135 nations and the European Union had signed the Basel Convention. The convention, however, does not include the United States, one of the world’s largest hazardous waste producers.
Hazardous wastes that need treatment or disposal may be freshly generated from an industrial operation, they may be old stored chemicals, or they may have been sitting in a dump for many years. At a dump, component chemicals difficult to identify, they are likely to have reacted with one another, and they may have already affected the surrounding soil and water. Land disposal and incineration are two main dumpsite remediation methods. Types of waste treatment include physical, biological, and chemical neutralization or stabilization. Some treated hazardous wastes can even be reclaimed or recycled.
Industries in the United States dispose of about 60% of their hazardous waste using a land disposal method called deep well injection. Liquid wastes are injected into wells located in impervious rock formations intended to keep the waste isolated from ground-water and surface water. Hydrogeologists now predict, however, that groundwater flow does occur in most previously designated impervious rock formations, and injected waste can migrate into groundwater reservoirs called aquifers. Other underground burial locations for hazardous wastes include deep mines, natural caverns, and man-made deep pits.
Landfilling is the other primary land disposal method for hazardous waste disposal in the United States. Hazardous waste landfills are similar to regular solid waste landfills, but they must meet much higher standards for safety and environmental protection. The EPA requires that most hazardous wastes be treated before being discarded in properly-designed, approved landfills and burial sites.
Incineration, or burning, is a controversial, but still common, method of handling hazardous wastes. The EPA estimates that five million tons of hazardous wastes are burned each year in the United States. Various incineration technologies exist for a variety of types of waste. For example, volatile chemicals like paint thinners, oils, and solvents are destroyed by combustion at cement plants whose furnaces, called kilns, reach temperatures of 2,700°F (1,500°C). Residents living near cement plants and other hazardous waste incinerators often have concerns about air pollution. In 1993, the EPA tightened its regulations on emissions from most hazardous waste incinerators, including cement kilns, after discovering that the emissions contained like dioxins, furans, and other substances that cause cancer and other health problems in humans. Another recent EPA study noted that medical waste incinerators that many hospitals use to burn hazardous wastes also emit dioxins.
Some hazardous wastes, including certain tars, drilling muds, and mining sludges, are relatively well-suited for incineration. Some other wastes, however, should not be burned, such as those that contain heavy metals. Burning does not destroy the metals, and they end up in the incinerator ash. Ash from hazardous waste incinerators that contains high concentrations of metals is a dangerous material in its own right, and requires careful disposal.
Stabilization, also called solidification, is a physical treatment method sometimes used on incinerator ash and other hazardous wastes before landfilling or underground burial. In this method, additives are combined with the waste material to make it more solid, or to prevent chemical reactions. Other physical treatment methods include soil washing at hazardous waste dumpsites, filtering hazardous waste solids out of liquids, and distillation.
Various biological treatments utilize microbes to break down wastes through a series of organic chemical reactions. Through these methods, substances that could cause damage to humans or the environment can be rendered harmless. New substances created by microbial reactions may be suitable for reuse or recycling. Research in genetic engineering, though controversial, could lead to breakthroughs in biological treatment. In chemical treatment, materials are added to or removed from the hazardous waste to produce new, less hazardous chemicals. Chemical neutralization, for example, involves mixing a corrosive acid with carbonate lime or another high-pH material until it is no longer acidic.
In the 1990s, government regulators and others recognized the strengths of waste prevention as a tool for managing hazardous wastes. Waste prevention means using smaller quantities of potentially harmful
Superfund —A fund created by the U.S. Congress to help clean up hazardous waste dumpsites.
Toxic waste —A type of hazardous waste that is capable of killing or injuring living creatures.
Waste prevention —A waste management method that involves preventing waste from being created, or reducing waste.
materials or ptproducts, or using materials that are less toxic. The obstacles encountered by CERCLA underscored a need to manage hazardous waste by preventing its creation in the first place. Waste prevention is less expensive than treatment or disposal because it does not require transportation, processing or cleanup. It also can save on product production costs because fewer resources are needed. Furthermore, much of the environmental and human health damage caused by hazardous waste contamination is irreversible.
Businesses can prevent hazardous waste problems in a number of ways: they can reuse hazardous chemicals, improve storage and transportation methods, substitute less dangerous chemicals for more dangerous one, redesign production methods to eliminate the need for hazardous materials, and improve record-keeping and labeling of materials. Prevention measures often carry a significant up-front expense, but such waste prevention projects usually pay for themselves. Sometimes the financial benefit of prevention takes years to become apparent, but often the gain is almost immediate. Exxon Corporation, for example, spent about $140,000 to redesign several chemical storage tanks. The improvement allowed the company to reduce its chemical use by 700,000 lb (318,000 kg), and to save more $200,000 a year. Lower disposal, treatment, and shipping costs aren’t the only benefits to companies that instate waste prevention practices. More efficient record-keeping, reduced legal liability, safer employee work conditions, and improved public image all promote a business’s economic success.
Macey, G. and J.Z. Cannon, eds. Reclaiming the Land: Rethinking Superfund Institutions, Methods and Practices. Berlin: Springer, 2006.
National Research Council. Superfund and Mining Megasites: Lessons from the Coeur D’alene River Basin. Washington, DC: National Academies Press, 2006.
"Hazardous Wastes." The Gale Encyclopedia of Science. . Encyclopedia.com. (July 18, 2019). https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/hazardous-wastes
"Hazardous Wastes." The Gale Encyclopedia of Science. . Retrieved July 18, 2019 from Encyclopedia.com: https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/hazardous-wastes
Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).
Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.
Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:
Modern Language Association
The Chicago Manual of Style
American Psychological Association
- Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
- In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.