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Hazardous Waste

Hazardous Waste

The Resource Conservation and Recovery Act (RCRA), enacted in 1976, defines hazardous waste as a liquid, solid, sludge, or containerized gas waste substance that due to its quantity, concentration, or chemical properties may cause significant threats to human health or the environment if managed improperly. U.S. legislation considers a waste hazardous if it is corrosive, flammable, unstable, or toxic. Sources of hazardous waste may include industry, research, medical, household, chemical producers, agriculture, and mining, as well as many others.

Most hazardous waste comes from industrial sources. The EPA specifies four different categories of hazardous waste that are subject to regulation: hazardous wastes from nonspecific sources involved in industrial processes such as spent halogenated solvents; hazardous wastes from specific industrial sources, such as untreated wastewater from the production of the herbicide 2,4-dichlorophenoxyacetic acid (2,4,-d); commercial chemical products that may be discarded (such as benzene) used in the manufacture of drugs, detergents, lubricants, dyes and pesticides; and wastes that are classified as toxic, such as vinyl chloride. Hazardous waste from many industrial processes include solvents such as methylene chloride, a probable carcinogen that is commonly used in paint removers. Trichloroethylene, a solvent that has been found in groundwater is monitored and regulated in drinking water in the United States. Drinking or breathing high levels of trichloroethylene can lead to damage of the liver, lung, and nervous system. In many industries the sludge remaining after treatment of wastewater accounts for much of the generated hazardous waste. Sludges and wastewater from electroplating operations commonly contain cadmium, copper, lead, and nickel. These heavy metals are found in the sediment of Lake Huron and have been associated with degradation of benthos and planktonic communities. Heavy metals can impact the health of humans and wildlife in a variety of ways: lead interferes with the nervous system and can lead to learning disabilities in children and cadmium accumulates in humans and animals and can lead to kidney disfunction. Household products that contain hazardous ingredients are not regulated under RCRA but should be disposed of separately from municipal garbage following label instructions. Household hazardous waste (HHW) can include used motor oil, paint thinners and removers, wood preservers, batteries, fluorescent lights that contain mercury, and unused pesticides.

The U.S. Environmental Protection Agency (EPA) and state regulatory agencies collect information about the generation, management, and final disposal of hazardous wastes regulated under RCRA. This report gives detailed data on hazardous waste generation and waste management practices for treatment, storage, and disposal facilities.

Waste Minimization and Recycling

Recycling and waste minimization may be the best ways to deal with hazardous waste. Waste minimization reduces the volume of waste generated, whereas recycling means that less hazardous waste requires disposal. Techniques for waste minimization may include audits, better inventory management, production process/equipment modifications, and operational/maintenance procedures. Raw material changes, volume reductions, nonhazardous material substitutions, reuse, or recovery also reduce hazardous waste production. For example biodegradable, nontoxic lactate esters are solvents manufactured from renewable carbohydrate sources that can be substituted for toxic halogenated solvents.

The EPA's Industrial Toxics Project is a nonregulatory program initiated in 1990 to achieve, voluntarily, overall reductions for seventeen toxic chemicals reported in the government's Toxics Release Inventory (TRI), including cadmium, lead, mercury, trichloroethylene, and toluene. The recycling of waste through waste exchanges is one aspect of industrial ecology and another way to address the issue of hazardous waste disposal. For example the sludge that accumulates in scrubbers removing sulfur dioxide from power plant smokestacks contains calcium sulfate, which can be recycled in wallboard. Waste exchange also promotes the use of one company's waste as another company's raw material. Waste exchanges typically list both available and desired materials. Several regional waste exchanges exist, as well as exchanges within small geographic regions. Some exchanges charge for their services, whereas others are supported by grants.

Disposal Options and Problems

Disposal options for hazardous waste include landfills, injection wells , incineration, and bioremediation , as well as several others. The greatest concern with the disposal of hazardous waste in landfills or injection wells is that toxic substances will leak into surrounding groundwater. Groundwater is a major source of drinking water worldwide and once it is contaminated, pollutants are extremely difficult and costly to remove. In some instances, it is impossible to remove groundwater contamination. The ideal disposal method is the destruction and conversion of hazardous waste to a non-hazardous form. New technology for hazardous and mixed low-level radioactive waste conversion includes a high-temperature plasma torch that converts low-level radioactive wastes to environmentally safe glass. Conversion to environmentally safe substances can be very expensive for some types of hazardous wastes and technically impossible for others, creating the need for alternative disposal methods.

The most common form of hazardous waste disposal in the United States is landfilling. Hazardous waste landfills are highly regulated and are required to include clay liners, monitoring wells, and groundwater barriers. The 1984 Hazardous Solid Waste Amendments require the monitoring of groundwater near landfills for thirty years. Injection wells may be used to inject hazardous waste deep into the earth, but problems result with aquifer contamination and the ultimate fate of the hazardous waste after injection is unknown.

Incineration may be an effective way to convert hazardous waste into a nonhazardous form while greatly decreasing its volume. The waste is burned and converted into carbon dioxide, water, and inorganic by-products. The problems associated with incineration are high capital and operating costs, and the disposal of ash, which may contain hazardous substances. In addition, incinerating wastes can cause mercury and dioxin air pollution. Bioremediation may also be used in situ or ex situ to convert hazardous wastes to nontoxic by-products using microorganisms and natural degradation processes. Biodegradation requires very long treatment times and it may be difficult to control or enhance natural degradation processes. Phytoremediation, the process by which plants absorb and in some cases degrade hazardous substances in the environment, is being investigated as an emerging cleanup technology. For example poplar trees have been shown to break down the herbicide atrazine, mustard plants will remove lead from soil, and the alpine pennycress plant will take large amounts of heavy metals and also uranium from soil.

When hazardous waste is to be transported off-site for disposal, the waste generator prepares a shipping document called a manifest. This form must accompany the waste to its final destination and is used to track the waste's movements from "cradle to grave."

Hazardous Waste Production in the United States

Facilities that produce hazardous waste, usually as a result of an industrial process, are considered large-quantity generators (LQG) or small-quantity generators (SQG) depending on the quantities produced. Hazardous waste may be transported to alternate locations to be treated, stored, or disposed of, or may be managed at the place of generation.

In 1995, 20,873 LQGs produced 214 million tons of hazardous waste regulated by RCRA. There were 3,489 fewer LQGs and a reduction of 44 million tons of waste by 1995 compared to 1993. The five states generating the largest amount of hazardous waste were Texas (69 million tons), Tennessee (39 million tons), Louisiana (17 million tons), Michigan (13 million tons), and Illinois (13 million tons), accounting for 70 percent of the national totals.

The industrial trade of hazardous waste has become an extensive problem. Many third world countries accept large volumes of hazardous waste for disposal in return for sizable financial compensation. Unfortunately, the large profits reaped by such poor countries do not compensate for the long-term environmental impacts from improperly managed hazardous waste. Many wastes have also been dumped illegally on international shores where environmental regulation and controls are often lacking.

see also Abatement; Brownfield; Cleanup; Green Chemistry; Incineration; Industrial Ecology; Injection Well; Landfill; Medical Waste; Radioactive Waste; Resource Conservation and Recovery Act; Waste, Transportation of.


Davis, Mackenzie L., and Cornwell, David A. (1998). Introduction to Environmental Engineering. Boston: McGraw-Hill.

Graedel, T.E., and Allenby, B.R. (1995). Industrial Ecology. Upper Saddle River, NJ: Prentice Hall.

La Grega, Michael D.; Buckingham, Philip L.; Evans, Jeffrey C.; and Environmental Resources Management. (2001). Hazardous Waste Management. Boston: McGraw-Hill.

Vesiland, P. Aarne; Worrell, William; and Reinhart, Debra. (2002). Solid Waste Engineering. Australia: Brooks/Cole.

Watts, Richard J. (1998). Hazardous Wastes: Sources, Pathways, Receptors. New York: John Wiley & Sons.

Margrit von Braun and Deena Lilya

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Hazardous Waste


HAZARDOUS WASTE is a by-product, usually of manufacturing, medical and scientific research, and consumer detritus (disintegrating materials), that is dangerous to human health and wildlife. The substances defined as hazardous received their initial analysis in the industrial hygiene movement between 1900 and 1930, which focused on substances in the workplace. The movement's concern with hazardous industrial substances seldom extended beyond the factory walls. Although public health authorities in the late nineteenth century considered industrial pollution a major problem, the focus shifted after the acceptance of the germ theory of disease. Public health officers and sanitary engineers focused on bacterial wastes as the primary threat to human health. When they considered industrial wastes, they concentrated on their non-pathogenic effects. It was only after World War II that professionals began to pay greater attention to health and the environment.

The first federal legislation regarding hazardous waste was the 1970 Solid Waste Disposal Act. Section 212 required that the Environmental Protection Agency (EPA) investigate the storage and disposal of hazardous wastes. The resulting 1974 report to Congress on the disposal of hazardous wastes led to the passage in 1976 of the Resource Conservation and Recovery Act (RCRA), which defined hazardous wastes that can cause illness or pose a hazard to health and to the environment when improperly stored, transported, or managed. In 1980, the EPA announced regulations implementing cradle-to-grave controls for handling hazardous wastes.

RCRA did not touch on the dangers of wastes buried in industrial and municipal landfills. For decades, industries had disposed of hazardous materials in landfills. Land disposal of wastes increased in the post-World War II period, as states put limits on water disposal. These older sites, in many cases abandoned or closed, posed a threat to groundwater supplies. The case of Love Canal, a chemical waste dump formed by the Hooker Chemical and Plastics Corporation in Niagara Falls, New York, and from which toxic chemical wastes migrated to endanger neighboring residential areas, focused public and govern-mental attention on the problem in the late 1970s.

Congress responded to the perceived danger of these sites in 1980 by approving the Comprehensive Environ-mental Response, Compensation, and Liability Act (CERCLA), or Superfund, which provided $1.6 billion for the cleanup of toxic wastes. Under CERCLA, the EPA established procedures of site-specific risk assessments to determine whether the hazardous wastes were a threat to human health. The Superfund Amendments and Reauthorization Act in 1986 increased the fund to $9.6 billion. The Superfund Act and its amendments sought to cover the costs of cleanup by requiring retrospective liability. That is, it made those people and companies responsible for creating hazardous waste sites liable for the costs of cleanup. The amendments also required that firms that imported, processed, or produced more than 50,000 pounds per year of any of the EPA's listed chemicals and compounds, register them in the EPA's annual Toxics Release Inventory. The slow pace of cleanups, however, as well as cumbersome procedures, convinced many experts that Superfund was not only underfunded but imposed unreasonable standards of cleanliness, given future site uses.

One of Superfund's main tools was a trust fund that contained money contributed by corporations that were taxed to help pay for cleanup operations at Superfund sites. In 1995, that legislation expired. In the following years, Democratic President Bill Clinton annually attempted to renew the legislation, but the Republican-controlled legislature consistently blocked his efforts. Once Republican President George W. Bush came into office, the White House ceased to agitate for renewal. Many critics see the Superfund program as fundamentally flawed because it spends too much money in court battles to determine who is responsible for cleaning up hazardous sites. Furthermore, they argue that taxing the chemical and petrochemical industries to clean up sites that they did not pollute is unfair. In 2001, $860 million was available for Superfund cleanup, but that amount was projected to fall to $28 million by 2003.


Anderson, Terry L., ed. Political Environmentalism: Going Behind the Green Curtain. Stanford, CA: Hoover Institution Press, 2000.

Barnett, Harold C. Toxic Debts and the Superfund Dilemma. Chapel Hill: University of North Carolina Press, 1994.

Hird, John A. Superfund: The Political Economy of Environmental Risk. Baltimore: Johns Hopkins University Press, 1994.

Mazur, Allan. A Hazardous Inquiry: The Rashomon Effect at Love Canal. Cambridge, Mass: Harvard University Press, 1998.

Switzer, Jacqueline Vaughn. Environmental Politics: Domestic and Global Dimensions. New York: St. Martin's Press, 1994; 1998.

Joel A.Tarr/a. e.

See alsoEnergy, Department of ; Energy Industry ; Environ-mental Business ; Environmental Protection Agency ; Times Beach ; Waste Disposal ; Water Pollution .

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Hazardous Waste


All human activities generate some form of waste. In its most general sense, the term "hazardous waste" comprises toxic chemicals, radioactive materials, and biologic or infectious waste. Hazardous waste poses a threat to workers through occupational exposure and to the public through exposure in homes, communities, and the general environment. Exposure may occur near the site of generation, along transportation corridors, and near the ultimate disposal sites. Most hazardous waste results from industrial processes that yield unwanted intermediates, products that fail quality control, and spilled material.

Hazardous waste management is divided into two main areas: currently generated waste, which is regulated under the Resource Conservation and Recovery Act (RCRA) of 1976, and waste at abandoned sites, which is regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. The Environmental Protection Agency (EPA) has jurisdiction and responsibility for managing the "cleanup" of hazardous waste sites. The Agency for Toxic Substances and Disease Registry (ATSDR), a branch of the Centers for Disease Control and Prevention (CDC), evaluates and assists communities that have been exposed to hazardous waste.

Under RCRA, industries assume responsibility for all of the waste they generate. They may manage it on-site or ship it off-site. In the latter case they retain responsibility, even when it has reached a legal disposal site. This is termed "cradle-to-grave" responsibility. Under CERCLA (also known as the Superfund Act), states may petition the EPA to have a hazardous waste site listed on the National Priorities List. This makes the site eligible for federal cleanup assistance in the event that a responsible party is not identified or does not accept responsibility.

Under RCRA, solid waste is defined as hazardous if its "quantity, concentration, or physical, chemical, or infectious characteristic" leads to death or serious illness or otherwise poses a "substantial present or potential hazard to human health or the environment, when improperly treated, stored, transported, or disposed of, or otherwise mismanaged." Under the Toxic Substances Control Act, more than 55,000 individual chemicals can fit the definition of a hazardous waste.

The main types of hazardous wastes are depleted raw materials, reaction products, tank residues, filter cake, precipitates, and spent solvents. They may be disposed of in liquid or solid form, either contained or uncontained. Wastes must be listed on a manifest, hauled by a licensed hauler, and disposed of at an approved hazardous waste site.

It is estimated that hazardous chemical wastes have been stored at more than 50,000 sites in the United States alone, although only 1,500 are listed on the National Priorities, or Superfund, List. To be listed, a site must be assessed using the EPA Hazard Ranking System. Once the site is identified, a preliminary site assessment is performed to determine if there is a potential hazard. If a hazard exists, there may be emergency remediation, but typically the second phase is a remedial investigation/feasibility study that categorizes a site and identifies remediation options. Remediation may range from an enclosure and warning signs to complete removal of waste, capping, and treatment of groundwater.

The Hazard Ranking System yields three scores, involving: (1) the possibility of offsite migration; (2) the likelihood of human receptors coming in contact with contaminated air, water, soil, or organisms; and (3) the explosivity or fire hazard posed by the material.

The ten substances most often identified at Superfund sites are: trichloroethylene, toluene, benzene, lead, chloroform, polychlorinated biphenyls (PCBs), tetrachloroethylene, phenol, trichloroethane, and chromium. The receptor populations include not only neighbors living adjacent to industrial sources or waste sites, but emergency responders, public safety officials, regulatory agency personnel, and hazardous-waste remediation workers.

Pathways of exposure include: direct contact with contaminated soil from playing or working on or adjacent to a waste site, consumption of contaminated groundwater, inhalation of vapors or dust from a site, and consumption of contaminated food stuffs.

Michael Gochfeld

(see also: Agency for Toxic Substances and Disease Registry; Benzene; Environmental Determinants of Health; Environmental Protection Agency; Hazardous Waste; Landfills, Sanitary; Lead; Municipal Solid Waste; Nuclear Waste; Occupational Safety and Health; PCBs; Pollution; Toxic Substances Control Act; Toxicology )


Gochfeld, M. (1995). "Hazardous Waste." In Textbook of Occupational and Environmental Medicine, eds. L. Rosenstock and M. Cullen. Philadelphia, PA: W. B. Saunders.

Gochfeld, M., and Burger, J. (1995). "Assessment and Mediation of Hazardous Waste Sites." In Environmental Medicine, ed. S. Brooks et al. St. Louis, MO: Mosby.

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