459 HAZARDOUS WASTES A hazardous waste is a solid waste than may (1) cause or significantly contribute to an increase in serious irreversible or incapacitating reversible illness, or (2) pose a substantial threat or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed. Hazardous wastes are managed under two categories: (1) waste material currently being gener- ated and subject to control by the Resource Conservation and Recovery Act (RCRA), and (2) wastes that have accu- mulated at inactive or abandoned sites or wastes result- ing from spills that require emergency response. Both are addressed by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund. The RCRA identifies hazardous wastes based upon lists of specific wastes and four characteristics. All waste genera- tors are required to determine if any of these four character- istics are exhibited by their wastes. SOLID WASTES Hazardous wastes are managed as part of solid wastes; there- fore, a discussion of the legal definition of solid waste is nec- essary. The word “solid,” in this case, is misleading, because solid wastes can include liquids and contained gases. Thus, the important term is “waste,” which is any material that is dis- carded—for example, discarded military munitions are con- sidered solid wastes. Recycling has become a major factor in waste management, and the manner in which a waste is recy- cled determines whether it is to be treated as a solid waste. Material in a waste stream that is recycled by introducing it directly as an ingredient in a production process is not a solid waste, nor is it a solid waste if it is used as a substitute for a commercial product. On the other hand, waste disposed of by burning as a fuel, or in fuels, is a solid waste, as is material containing dioxin. If wastes are stored for recycling but are not 75% recycled in a calendar year, they are solid wastes. Certain specific types of wastes, such as untreated domestic sewage, industrial wastewater discharges, irriga- tion return flows, and nuclear materials as defined by the Atomic Energy Act of 1954, are excluded from the defini- tion as solid wastes. HAZARDOUS WASTES The growth of industry during World War II was accompanied by a great increase in the generation of hazardous wastes. It is estimated that this increase was accelerated after the war from half a million metric tons per year to almost 280 million metric tons by 1995. This phenomenal rate of growth caused Congress to react by passing the RCRA in 1976 as an amendment to the Solid Waste Disposal Act (SWDA) of 1965. The RCRA itself has been amended several times, most significantly in 1984 by the Hazardous and Solid Waste Amendments (HSWA) of 1984. The management of underground storage tanks (USTs) was included among the amendments. There are three subtitles in the RCRA that have spe- cial significance to hazardous wastes. Subtitle C describes the hazardous-waste program, and Subtitle I describes the underground storage-tank problem. Subtitle D, which per- tains to solid wastes, is important because a hazardous waste must first be identifiable as a solid waste. As directed by Congress, the Environmental Protection Agency (EPA) has defined hazardous wastes by listing certain specific solid wastes as hazardous and by identifying charac- teristics of a solid waste that make it hazardous. Is a waste Hazardous? 1. Is the waste excluded? (40 CFR 261.4) Code of Federal Regulations If not, 2. Is it listed? (40 CFR 261, Subpart D) F Non specific sources such as spent solvents. K Source specific wastes. P - U Discarded products, off-spec material, con- tainer or spill residues. If not, 3. Is it a characteristic waste? (40 CFR 261 Subpart C) All of the wastes on these lists are assigned an identifica- tion number. All listed wastes are presumed to be hazardous regardless of their concentration and must be handled accord- ing to Subtitle D of RCRA. © 2006 by Taylor & Francis Group, LLC 460 HAZARDOUS WASTES Hazardous-Waste Characteristics A waste that falls into one of the lists must still be examined to determine if it exhibits one or more of these characteristics: ignitability, corrosivity, reactivity, or toxicity. If it does, it is considered to represent an additional hazard and may necessitate special regulatory precautions. Ignitability: Liquid wastes with a flash-point test less than 60°C and nonliquids that spontaneously catch fire through friction or by reaction with moisture and materials that meet the Department of Transportation definition of an oxidizer Corrosivity: Aqueous wastes with a pH greater than or equal to 12.5 or less than or equal to 2, and liquids that can readily corrode or dissolve flesh, metal, or other materials (liquids that corrode steel at greater than 0.25 in. per year at 55°C) Reactivity: Wastes that readily explode or undergo violent reactions, for example, sodium hydride Toxicity: Wastes likely to leach chemicals into groundwater when discarded, for example, in a municipal landfill The EPA designed a procedure called the toxicity char- acteristic leaching procedure (TCLP) to be used to deter- mine the leachability of a waste. If the leachate contains an amount of any of 40 different toxic chemicals above its regulatory level, the waste is given the waste code associated with that compound or element. Excluded Wastes (40 CFR 261.4) Certain wastes have been excluded from hazardous wastes for practical or economic reasons. Wastes are excluded because: • They fall within 19 categories that are listed as not solid wastes • They fall within 17 categories that are listed as not hazardous wastes • They are regulated under other laws, such as the Clean Water Act or the Atomic Energy Act • They are generated in laboratory experiments or waste-treatability studies • They are generated in raw material, product stor- age, or manufacturing units Examples: Domestic sewage discharged into a sewer to a munic- ipal wastewater treatment plant, regulated under the Clean Water Act Certain radioactive materials that are regulated by the Atomic Energy Act Scrap metal that has been processed to make it easier to handle Circuit boards that have been shredded and are free of potentially dangerous materials Household wastes generated by normal household activities that could technically be considered hazardous wastes Certain wastes from the exploration and production of oil, gas, and geothermal energy Treated wood containing hazardous materials such as arsenic that is discarded by end users Dredge materials subject to the Marine Protection, Research, and Sanctuaries Act of 1972 Underground Storage Tanks The greatest potential hazard from underground tanks is leakage that will contaminate groundwater. The EPA estimates that about 25,000 tanks out of 2.1 million regulated tanks contain hazardous mate- rials. In 1984, Congress added Subtitle I to the RCRA to initiate a program to protect the environment from under- ground tanks leaking petroleum products and other hazard- ous materials. For practical and economic reasons, many tanks are excluded from meeting federal requirements (but not neces- sarily state or local): • Tanks of 1,100 gallons or less used to hold motor fuels for noncommercial purposes on farms and residences • Tanks for heating oil used on the premises where tank is stored • Tanks in basements or tunnels • Septic tanks and storm and wastewater collectors • Tanks with a capacity of 110 gallons or less The nature and complexity of the program led the federal government to allow approved state programs to act in its place. Inasmuch as state regulations can be more stringent, it is important that anyone concerned about underground stor- age tanks be familiar with state requirements. The Petroleum Equipment Institute Web site presents a map showing which states regulate tanks; however, it is recommended that your local regulatory agency be consulted. LUST, the program for leaking underground storage tanks, is funded by a 0.1-cent federal tax on every gallon of motor fuel sold in the country. Accumulated Wastes Past practices have left huge quantities of hazardous wastes deposited in landfills, ponds, fields, and storage in a manner that threatens our health and environment. Surface and groundwater supplies of drinking water are especially sen- sitive to contamination by these accumulations, which can take thousands of years to clean themselves. Depending on the type of contamination, treatment may be impractical or prohibitively expensive. The federal government response to the problem of accumulated wastes and emergencies that release haz- ardous wastes was CERCLA, commonly referred to as Superfund. This law was enacted by Congress December 11, 1980, and amended by the Superfund Amendments and © 2006 by Taylor & Francis Group, LLC HAZARDOUS WASTES 461 TABLE 1 Toxicity-characteristic waste The D List If your waste contains one or more of these contaminants at or above the regulatory level, it is a hazardous waste. Maximum Concentration of Contaminants for the Toxicity Characteristic EPA Waste # Contaminant CAS No. Regulatory Level (mg/l) D004 Arsenic 7440-38-2 5.0 D005 Barium 7440-39-3 100.0 D018 Benzene 71-43-2 0.5 D006 Cadmium 7440-43-9 1.0 D019 Carbon tetrachloride 56-23-5 0.5 D020 Chlordane 57-74-9 0.03 D021 Chlorobenzene 108-90-7 100.0 D022 Chloroform 67-66-3 6.0 D007 Chromium 7440-47-3 5.0 D023 o-Cresol 95-48-7 200.0* D024 m-Cresol 108-39-4 200.0* D025 p-Cresol 106-44-5 200.0* D026 Cresol — 200.0* D016 2,4-D 94-75-7 10.0 D027 1,4-Dichlorobenzene 106-46-7 7.5 D028 1,2-Dichloroethane 107-06-2 0.5 D029 1,1-Dichloroethylene 75-35-4 0.7 D030 2,4-Dinitrotoluene 121-14-2 0.13 D012 Endrin 72-20-8 0.02 D031 Heptachlor (and its epoxide) 76-44-8 0.008 D032 Hexachlorobenzene 118-74-1 0.13 D033 Hexachlorobutadiene 87-68-3 0.5 D034 Hexachloroethane 67-72-1 3.0 D008 Lead 7439-92-1 5.0 D013 Lindane 58-89-9 0.4 D009 Mercury 7439-97-6 0.2 D014 Methoxychlor 72-43-5 10.0 D035 Methyl ethyl ketone 78-93-3 200.0 D036 Nitrobenzene 98-95-3 2.0 D037 Pentachlorophenol 87-86-5 100.0 D038 Pyridine 110-86-1 5.0 D010 Selenium 7782-49-2 1.0 D011 Silver 7440-22-4 5.0 D039 Tetrachloroethylene 127-18-4 0.7 D015 Toxaphene 8001-35-2 0.5 D040 Trichloroethylene 79-01-6 0.5 D041 2,4,5-Trichlorophenol 95-95-4 400.0 D042 2,4,6-Trichlorophenol 88-06-2 2.0 D017 2,4,5-TP (silvex) 93-72-1 1.0 D043 Vinyl chloride 75-01-4 0.2 * If the o-, m-, and p-cresol concentrations cannot be differentiated, the total cresol (D026) concentration is used. The regulatory level of total cresol is 200 mg/l. © 2006 by Taylor & Francis Group, LLC 462 HAZARDOUS WASTES Reauthorization Act (SARA) on October 17, 1986, creating a hazardous-waste-site response program and liability scheme that authorizes the government to hold persons who caused or contributed to the release of hazardous substances liable for the cost or the cleanup of affected sites. The president or the delegated agency is authorized to draw funds from a revolving trust fund (Superfund) to respond to releases of hazardous substances: (1) the EPA can take action at the site using Superfund money that it can recover from potentially responsible parties (PRPs), (2) the EPA can order PRPs directly or through a court to clean up a site, and (3) the EPA can enter into settlement agreements with PRPs that require them to clean up or pay for the cleanup of a site. Superfund money can be used for sites that meet the fol- lowing criteria: (1) The site is listed on the National Priority List (NPL). (2) The state in which the site is located either con- tributes or provides financial assurances for 10% of any remedial costs incurred. (3) The remedial action is not inconsistent with the National Oil and Hazardous Pollution Contingency Plan (NCP). The NCP was revised in 1994 to reflect the oil-spill provisions of the Oil Pollution Act of 1990 (OPA). To establish that a person is liable under CERCLA, the EPA must prove that a hazardous substance was released from a facility that caused the government to incur costs in responding. CERCLA imposes liability on current and former owners and operators of a facility, persons who arranged for treatment or disposal of hazardous substances, and transporters of hazardous substances who selected the disposal site. Planning Ahead The Toxic Substances Control Act (TSCA), which became law on October 11, 1976, authorizes the EPA to secure infor- mation on all new and existing chemical substances and to control any that were determined to be unreasonable risks to public health or the environment. The Asbestos Hazard Emergency Response Act (AHERA) amended the TSCA on October 22, 1986, and the Radon Reduction Act amended it in October 1988. In 1990 AHERA was amended by the Asbestos School Hazard Abatement Reauthorization Act, which required accreditation for persons conducting asbes- tos inspection and abatement activities in schools and com- mercial and public buildings. The TSCA was amended in October 1992 to add the Lead-Based Paint Exposure Reduction Act. All manufacturers and importers, processors, distributors, and users of chemical substances may be subject to TSCA reporting, record keeping, and testing requirements. Penalties for noncompliance may be up to $27,500 per violation per day. The demand for greater environmental protection at less cost led the EPA to recommend a one-stop approach toward controlling the release of pollutants from different types of facilities in the May 10, 1996, Federal Register. This Public Performance-Based Permitting Program (P3) is oriented toward identifying the actual impact on the environment, the compliance over time, and how well the enforcement agen- cies perform. The ultimate approach to the prevention of exposure of the public and contamination of the environment by hazard- ous wastes is to find ways to produce what we need while minimizing the hazardous side products. The flood of legis- lation and its costs in money and time to industry has helped to generate a movement sometimes known as “green tech- nology” that introduces environmental consciousness at the early stages of product development. Industry’s aim for a maximum yield is being tempered by the necessity to mini- mize unwanted and costly-to-dispose-of materials that must be classified as hazardous wastes. The Control of Exposures Certain factors must be understood and managed in control- ling exposures to hazardous materials: • Where in the environment have hazardous materi- als accumulated or are currently being introduced as a result of ignorance, carelessness, or criminal disregard for human health or the welfare of the environment? • How much hazardous material has accumulated or is being released? • What are the environmental pathways and mech- anisms by which these materials reach human receptors? • How hazardous are specific materials and how can their risks be estimated? • How can their generation be minimized? • How can their impact be minimized? • How best can the public be informed about the important aspects of hazardous material control? • How can the credibility of the agents responsible for informing and protecting the public be established? • How can the priority for control of hazardous materials be determined within the complex struc- ture of society’s problems? • How can public outrage, often generated by media treatment of environmental problems, be man- aged so that priorities and resources are directed to where they are most needed? The Effects of Exposures The prime motivation for continuing generation of laws to control exposures to hazardous materials has been the fear of cancer; however, it should be noted that there are other health perils inherent in exposures. Environmental expo- sures pertinent to carcinogenesis include not only hazardous materials but also diets, infectious agents, and even social behavior, as illustrated by the summary prepared in 1981 by © 2006 by Taylor & Francis Group, LLC HAZARDOUS WASTES 463 the Office of Technology Assessment of the Congress of the United States (Table 2). Determining the probability of cancer being caused at the concentration levels of a substance encountered in the environment is very difficult. Testing on human beings is not to be considered; therefore, accidental exposures are an important source of information, but the actual exposures and doses are usually poorly documented and existing records can be misleading. As a result, the use of animals as surro- gates is the usual alternative, with the size of the doses used and the difference in response between humans and animals as serious complicating factors. Toxicity and Risk Assessment Three elements must be present for a situation to have toxi- cological implications: 1. A chemical or physical agent capable of causing a response 2. A biological system with which the agent inter- acts to produce a response 3. A response that can be considered deleterious to the biologic system The deleterious response—that is, injury to health or the environment—should be significant. It is counterproductive to the goal of focusing our available resources on significant toxicological problems to include substances that cause only momentary discomfort or quickly reversible physiological change from the types of exposures that can be reasonably expected in daily life. There are no harmless substances if one does not place a limit on the type or extent of exposure. Nitrogen, oxygen, carbon dioxide, and water can all be harmful or even deadly under different types of exposures. Therefore, judgment must be used in making decisions about substances and the possibility of exposures at levels that can cause harm. Substances that can cause harm by interfering with or destroying the functions of organs can be distinguished from those whose mode of action is attack on cell growth and reproduction. Thus, the action of cyanide (which prevents tissues from using the oxygen provided by the blood) classifies it as dif- ferent from a carcinogen (which causes the abnormal pro- liferation of cells), a mutagen (which changes the genetic material and thus damages new cells), and a teratogen (which changes the cell framework of an embryo). Quantification of the risk associated with environmen- tal exposures is a major activity of environmental control. Originally, this effort focused on the effects of carcinogens; noncarcinogens were delegated to minority status. Now there is an increased level of concern about effects other than cancer—for example, the impact of synthetic chemi- cals on the endocrine system that can result in disruptions of the immune system or behavioral problem. The immu- notoxicity, neurotoxicity, teratogenicity, and toxicity to spe- cific body tissues of many compounds have not received significant attention in comparison to their mutagenicity and carcinogenicity. There is danger that once a substance’s carcinogenicity or noncarcinogenicity has been declared, its other harmful properties will be neglected. To evaluate the risk from exposure to a specific hazard- ous material, it is important to obtain as realistic as possible an estimate of the dose received by a representative individual via inhalation, ingestion of food or drink, and other possible ways that substances can be absorbed. In the case of children in contact with soil and other materials, both indoor and outdoor, the possibility of hand-to-mouth exposure must be considered. As an example, an individual living in the vicinity of an oper- ation that releases dioxin into the atmosphere is affected by both inhalation and by the amount of food and water ingested because of possible contamination from fallout. Obtaining the necessary dose data requires knowledge of emission rates and patterns, stack heights and local meteorological conditions, and TABLE 2 Summary of cancer-associated environmental factors Factor Sites Range of estimates Diet Digestive tract, breast endometrium, ovary 35 –50% Tobacco Upper respiratory tract, bladder, esophagus, kidney, pancreas 22–30% Asbestos Upper respiratory tract, others 3–18% Occupational Upper respiratory tract, others 4–38% Alcohol Upper digestive tract, larynx, liver 3–5% Infection Uterine cervix, prostate, and other sites 1–5% Sexual development, reproductive patterns, and sexual practices Breast, endometrium, ovary, cervix, testis 1–13% Pollution Lung, bladder, rectum 5% Medical drugs and radiation Breast, endometrium, ovary, thyroid, bone, lung, blood 1–4% Natural radiation Skin, breast, thyroid, lung, bone, blood 1–3% Consumer products Possibly all sites 1–2% Unknown—(e.g. new chemicals, dumps, stress) All sites ? © 2006 by Taylor & Francis Group, LLC 464 HAZARDOUS WASTES the topography of the land and its uses. The behavior patterns of the individual—that is, the time and places occupied, the food and drink ingested and its sources, and the possibility of direct ingestion of contaminated soil through work or play— must be factored in to obtain a realistic dose estimate. Estimation of the carcinogenic hazard of a substance has become a very complex procedure; however, the general idea can be presented in a model that calculates the indi- vidual or aggregate risk based on linear extrapolation from experimental data to zero dose of the curve relating dose to the probability of cancer. This assumes that there is no threshold for the incident of cancer, i.e., the only exposure for which there is zero prob- ability of cancer is zero exposure. The experimental data most convincing are those derived from studies of the human population supported by documented exposures and inci- dences of cancer. In most cases such data are not available; therefore animal-study data are used, with conservative fac- tors introduced to compensate for lack of information about interspecies relationships. The safety factors that have been used have been as large as 10,000—that is, in some cases the effects on humans are assumed to take place at exposures that can be as much as 10,000 times less than those causing similar effects on the surrogate species. The doses are commonly measured in terms of mil- ligrams of chemicals absorbed in the body each day per kilogram of body weight over a lifetime. For the part that is inhaled, it is customary to convert dosage units into micro- grams per cubic meter in the inhaled air. For the purposes of this conversion, a body weight of 70 kg is assumed and the inhaled volume is 20 cubic meters per day. 1 mg kg-day 70 kg person 1 20 person-day m g mg 3500 g m 3 3 ϫϫ ϫ ␮ ϭ ␮ 1000 Therefore, a bodily intake of 1 mg per kilogram of body weight per day is equivalent to the inhalation of air contain- ing 3500 µ g of the chemical per cubic meter. The unit risk value (URV) is the cancer probability corresponding to the inhalation over a lifetime of 70 years of air containing 1 µ g per cubic meter of the substance—that is, the risk is the ratio of the probability of cancer to the micro- gram per cubic meter inhaled: URV Probability of cancer gm 3 ϭ ␮ The URV multiplied by the average concentration inhaled over a lifetime is the individual lifetime risk of cancer: URV g m individual life time risk 3 ϫ ␮ ϭ The individual risk multiplied by the number in the popula- tion is the aggregate lifetime risk. A commonly used value to describe a hazardous substance is the atmospheric concentration that over a lifetime will result in one cancer per million inhabitants. URV g m 10 1 3 6 ϫ ␮ ϫϭ ␮ ϭ ϫ g m 1 URV 10 36 HAZARDOUS-WASTE INFORMATION Information about Superfund locations and hazardous- waste activities in your zip code, city, county, or state can be obtained over the Internet from the U.S. Environmental Protection Agency’s (EPA) Envirofacts Data Warehouse. REFERENCES Book of Chemical Lists (CD-ROM), Business and Legal Reports Inc. CERCLA/Superfund Orientation Manual, 1992 EPA Office of Solid Wastes and Emergency Response National Center for Environmental Assessment, EPA RCRA Orientation Manual, Jan. 2003, EPA 530-R-02–016 Toxicology Excellence for Risk Assessment, TERA@Tera.org EDWARD F. FERRAND Edward F. Ferrand Associates © 2006 by Taylor & Francis Group, LLC . 744 0-4 7-3 5.0 D023 o-Cresol 9 5-4 8-7 200.0* D024 m-Cresol 10 8-3 9-4 200.0* D025 p-Cresol 10 6-4 4-5 200.0* D026 Cresol — 200.0* D016 2,4-D 9 4-7 5-7 10.0 D027 1,4-Dichlorobenzene 10 6-4 6-7 7.5 D028 1,2-Dichloroethane. Trichloroethylene 7 9-0 1-6 0.5 D041 2,4,5-Trichlorophenol 9 5-9 5-4 400.0 D042 2,4,6-Trichlorophenol 8 8-0 6-2 2.0 D017 2,4,5-TP (silvex) 9 3-7 2-1 1.0 D043 Vinyl chloride 7 5-0 1-4 0.2 * If the o-, m-, and p-cresol. 10 7-0 6-2 0.5 D029 1,1-Dichloroethylene 7 5-3 5-4 0.7 D030 2,4-Dinitrotoluene 12 1-1 4-2 0.13 D012 Endrin 7 2-2 0-8 0.02 D031 Heptachlor (and its epoxide) 7 6-4 4-8 0.008 D032 Hexachlorobenzene 11 8-7 4-1