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It may seem easy – "waste" is everything that no longer has a use or purpose and needs to be disposed of, right? Right. The term certainly applies to discarded material, but there are specific definitions for waste that affect how waste is regulated and must be handled, especially in professional settings.


The majority of household and veterinary medical waste is considered "solid waste," regardless of whether it's actually "solid" in physical form. The U.S. Environmental Protection Agency (EPA) defines solid waste as "any garbage or refuse, sludge from a wastewater treatment plant, water supply treatment plant, or air pollution control facility and other discarded material, including solid, liquid, semi-solid, or contained gaseous material resulting from industrial, commercial, mining, and agricultural operations, and from community activities." Based on this definition, examples of solid waste generated by veterinary clinics include, but aren't limited to: animal tissues, fluids and carcasses; animal waste; chemicals used in laboratory, cleaning or radiographic procedures; syringes and other medical supply waste; some medications, such as epinephrine and nitroglycerin; chemotherapy agents; mercury from thermometers; light bulbs and batteries; pesticides; paint and other solvents; and more.


As you can tell, "solid waste" is a broad category. It is further subdivided into subcategories as shown in the chart on the right.


Medical Waste Definitions 

Solid waste is regulated on the federal level by the EPA in accordance with the Resource Conservation and Recovery Act (RCRA), which provides the EPA with the authority to regulate hazardous wastes from "cradle to grave." This includes when it's made to when it's disposed of, and everything in between.

Waste streamA waste stream is the flow or movement of wastes from the point of generation (e.g., a household or veterinary practice) to final disposal (e.g. incineration, landfill, etc.).


Hazardous waste

A subcategory of solid waste, the EPA defines hazardous waste as items that are classified as solid waste and that are potentially dangerous or harmful to the environment or human health. Hazardous waste is further subdivided into listed, characteristic, universal, dual, and mixed wastes. In addition to the broader categories relevant to veterinary practices, dual and mixed wastes need special attention because they may be under-recognized, leading to potential miscategorization and improper disposal. If either of these is generated at your facility, it is vital to make sure that the company you use to dispose of each of these is authorized to do so.


For more information:


Environmental Protection Agency (EPA) Hazardous Waste Regulations

  • 40 CFR 261 identifies and lists all hazardous materials regulated by Resource Conservation and Recovery Act (RCRA).

  • 40 CRF 262 discusses the requirements of hazardous waste generators, which depending on the situation, veterinarians may be classified.


Veterinary Compliance Assistance (VetCA)

  • Hazardous Materials—Overview

  • Hazardous Waste Determination

  • Reducing Hazardous Materials

    Listed waste

  • A subcategory of hazardous waste, listed waste is subdivided into 4 categories: F-listed, K-listed, P-listed and U-listed wastes. These substances are specifically defined in the RCRA. For more information on these types of waste, view the specific entries in the Code of Federal Regulations (CFR).

  • F-listed wastes are solid wastes from non-specific sources and include certain spent solvents and chemical baths as well as certain waste water items and other categories. These wastes are most likely to be found in the laboratory of a veterinary practice. Examples include acetone, methanol, toluene, xylene, and methylene chloride. Subcategories F001 through F005 are the most relevant for veterinary practices. (For more information: 40 CFR 261.31)


  • K-listed wastes include those generated during the manufacture of pesticides, pigments, chemicals, wood preservatives, etc. They are generally not found in veterinary practices, but may be found at facilities that manufacture veterinary pharmaceuticals. (For more information: 40 CFR 261.32)


  • P-listed wastes are products or chemicals that are acutely toxic, which means that a very small amount has severe or lethal effects (oral dose LD50 of 50 mg/kg or less), and include arsenic, warfarin, epinephrine, nitroglycerine, certain chemotherapeutic agents, and others. (For more information: 40 CFR 261.33)


  • U-listed wastes are products that are toxic and some also possess other characteristic waste properties such as ignitability, corrosivity or reactivity), and include acetone, chloral hydrate, ethylene oxide, formaldehyde, mercury, phenol, reserpine, certain chemotherapeutics, and others. (For more information: 40 CFR 261.33)








  • Characteristic wastes are hazardous solid wastes that possess the certain characteristics of ignitability, corrosivity, reactivity, or toxicity. (For more information: 40 CFR 261.20 – 261.24) You'll notice that this overlaps with the definition of U-listed wastes – characteristic waste is a category of waste that is somewhat of a "catch-all" for waste that isn't specifically listed (K-, F-, P- or U-listed) but possess one or more of the 4 characteristics of ignitability, corrosivity, reactivity or toxicity.





  • Mixed wastes are hazardous solid waste items that are radioactive. This includes waste materials associated with radionuclide (radioisotope) generation and use in veterinary medicine.



  • Dual wastes are both hazardous solid waste and infectious or potentially infectious items (regulated medical waste). Examples include non-empty syringes containing hazardous waste pharmaceuticals with needles attached.


  • As the name indicates, household hazardous wastes are hazardous solid wastes that are generated in small amounts by individual households across the nation. This category includes various household cleaners, paints, solvents and other chemicals. Some of the items in this category, such as batteries, light bulbs and pesticides, are also considered universal waste.


  • Non-hazardous wastes, which comprise the other category of solid waste, are solid wastes that do not meet the Resource Conservation and Recovery Act (RCRA) and are not subject to RCRA Subtitle C regulations. However, it is not safe to assume that waste classified as "non-hazardous" poses no risk. This category is further subdivided into municipal solid waste and industrial waste.



  • Municipal solid waste is a broad category of non-hazardous solid waste that includes animal carcasses as well as the typical garbage or trash.



  • Agricultural solid waste is a subcategory of municipal solid waste and is waste that is generated by the rearing of animals and the production or harvesting of crops or trees. This category includes animal waste and animal carcasses. (For more information: 40 CFR 246.101) 



  • Industrial solid waste is a second subcategory of non-hazardous solid waste and includes solid waste generated by industrial processes and manufacturing. This category also includes medical waste and regulated medical waste, which are particularly relevant for veterinarians.



  • Medical waste is industrial solid waste "generated in the diagnosis, treatment, or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biologicals" according to the Medical Waste Tracking Act of 1988. Depending on the situation, this category may include potentially infectious animal wastes, bedding, carcasses or tissues.


Regulated medical waste, more typically known as "biohazard" or "infectious" waste, includes the following:

  • Equipment, instruments, utensils, and fomites (any substance that may harbor or transmit pathogenic organisms) of a disposable nature from the rooms of patients who are suspected to have or have been diagnosed as having a communicable disease and must, therefore, be isolated as required by public health agencies;

  • Laboratory wastes, such as pathological specimens (e.g. all tissues, specimens of blood elements, excreta, and secretions obtained from patients or laboratory animals) and disposable fomites attendant thereto;

  • Surgical operating room pathologic specimens and disposable fomites attendant thereto and similar disposable materials from outpatient areas and emergency rooms.


For more information, see 40 CFR 246.101 (q)

​There is variation among states as to how they define and regulate waste generated by practicing medicine. On a federal level, the Occupational Safety and Health Administration (OSHA) and the Department of Transportation (DOT) are the primary oversight agencies.







Of the listed wastes, the P-, U- and F-listed (and, in particular, the F001-F005 subcategories) are the most important and should not be overlooked because violation of regulations regarding these products can result in strict disciplinary action.

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