Hazardous Waste Determination

This page will help you determine if a given waste material must be classified as hazardous.  The rules are spelled out in the Resource Conservation and Recovery Act (RCRA), and in the large body of regulations developed by the Environmental Protection Agency to implement RCRA. 

Please note that a special rule applies to hazardous waste pharmaceuticals that allows healthcare facilities to manage hazardous pharmaceutical waste in a manner that is better tailored to the healthcare industry and the common practices associated with the management of waste pharmaceuticals. In addition, this rule eliminates the dual regulation of hazardous waste pharmaceuticals that are also controlled substances regulated by the Drug Enforcement Administration (DEA). For more information, see: Hazardous Waste Pharmaceuticals.

It is important to know the correct classification of all of your facility's waste. The reason is that different sets of rules will apply to your facility depending on the total amounts of each type of hazardous waste that you generate per calendar month. Large quantity generators operate under more stringent rules than small quantity generators. The information on this page will help you determine what wastes to count toward the total.

Once you have determined the types and amounts of hazardous waste generated per calendar month at your facility, you will be able to find which rules apply to your facility by using the information provided on the page "Managing Hazardous (RCRA) Wastes" (see Generator status, EPA ID).

Please note that the regulations in your state may be different in some respects from the federal regulations.  Consult the HERC State Hazardous Waste Locator to find more information on your state's hazardous waste regulations.

Outline of the six steps

EPA recommends that you follow a six step process to determine whether a waste is hazardous.  The steps are listed below, expressed as a series of questions:

The steps are discussed in some detail in the following sections, with an emphasis on issues that would typically arise in healthcare facilities.  Because the issues can get complicated, the sections also provide links to more detailed information.

Is it "solid waste"?

The first step in determining if a material is a hazardous waste is to determine whether it is classified as a "solid waste".  The rules specify that a material cannot be a hazardous waste unless it is first determined to be a solid waste.

"Solid" for RCRA purposes doesn't mean what it means to you and me.  The regulatory usage of the term "solid" in this context is closer to the sense of the word "contained".

RCRA states:

“The term “solid waste” means any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility, and other discarded material including solid, liquid, semisolid or contained gaseous material…”  (US Code, Title 42, paragraph 6903, emphasis added)

So even gaseous material can, in some circumstances, qualify as a "solid waste".

Most materials of concern in healthcare facilities will fall under the "other discarded material" category in the RCRA definition.  So how can you recognize when material has been "discarded"?  According to EPA usage, there are three types of "discarded" material:

  1. Abandoned
  2. Recycled
  3. Inherently waste-like

Abandoned: In simplest terms, a material is considered "abandoned" if you plan to get rid of it. It clearly applies to material you have already disposed of, or that you have incinerated. It also applies to material that is being accumulated, stored and treated for eventual disposal.

It's not hard to imagine situations in which a facility and an inspector might have a difference of opinion about whether some stored material is or is not a waste.  Here are some of the questions the inspector might ask:

  1. Does the facility have a use for the material?
  2. Does the facility treat the material as if it was a valuable commodity?
  3. Does the facility plan to give it to someone else that has a use for it?

For example, suppose the inspector comes across a 55 gallon drum of solvent in the basement that is rusted, corroded and sitting in a pool of water. Even if the solvent is a valuable commodity, the facility is not ‘treating’ it as such.  They are treating it as waste. The inspector would be likely to consider it abandoned.

Recycled:  Specific types of recycled materials are considered ‘discarded’ and are therefore solid waste.

A material is normally considered to be discarded if it is:

  • used in a manner constituting disposal
  • burned for energy recovery
  • reclaimed
  • accumulated speculatively

"Speculative accumulation" refers to all those piles of material that you fully intend to recycle, but haven't quite gotten around to.  EPA will generally consider that your material is being "accumulated speculatively" if you cannot demonstrate a viable market for it, or if you have not recycled at least 75% of it in a given calendar year.

A material is also considered discarded if it is accumulated, stored or treated before recycling.

Please note that some materials that are reclaimed are not considered solid wastes under RCRA, even if they exhibit a characteristic of hazardous waste (like ignitability or corrosivity --  see below).  These include:

  • commercial chemical products
  • sludges
  • by-products

Similarly, commercial chemical products that are speculatively accumulated are also not solid wastes under RCRA.

Inherently waste-like:  Certain materials pose such a significant threat to human health that they are deemed "inherently waste-like" and are always considered solid wastes.  A standard example is any material containing dioxins -- that is in fact the only example so far.

In case of dispute:  It can sometimes happen that an inspector will consider that a particular material has been "discarded", and the facility will not agree.  In such a case, the facility will have to submit appropriate documentation to the inspector.  For example, if you are claiming that the material is a valuable commodity or has another use, you will need to show that you have a market for it, or that someone is actually taking and using it beneficially, etc.

Is it excluded?

The next step is to determine if the waste qualifies for an exclusion from RCRA regulation.  There are three main avenues:

  • solid waste exclusion
  • solid waste variance
  • hazardous waste exclusion
  • recycling

Solid waste exclusion:  There are some materials that are specifically excluded from the definition of "solid waste".  You can find a full listing in 40 CFR 261.4(a), but most cases are not likely to be relevant to healthcare facilities.  Examples include solid or dissolved material in domestic sewage, certain nuclear materials (already covered under the Atomic Energy Act), and a long list of materials from industrial and agricultural processes.

Regarding the case of domestic sewage, please be aware that this exclusion does not give you an opportunity to throw questionable waste down the drain and then claim that it's excluded under 40 CFR 261.4.  The purpose of that exclusion is to allow facilities like municipal sewage treatment plants (known as "publicly owned treatment works", or POTWs) to deal with their waste streams without having to comply with RCRA requirements that would be inappropriate for them.  Healthcare facilities must have a written agreement from their POTW to accept any waste that might qualify. 

Solid waste variance:  Another possible way to keep a particular material from being regulated under RCRA is to apply for a solid waste variance.   This option applies to:

  • Materials accumulated speculatively without sufficient amounts recycled
  • Materials reclaimed and reused within original process
  • Materials incompletely reclaimed

In order to use these variances, you will have to submit documentation demonstrating your case. If your state is authorized to administer the variance program, send the documentation to the director of your state agency.  Otherwise, send it to the EPA Regional Administrator.  You can find the rules governing solid waste variances in 40 CFR, sections 40 CFR 260.30, 40 CFR 260.31 and 40 CFR 260.33.

Hazardous waste exclusion:  Even if a material is indeed a solid waste, and even if it does not qualify for a solid waste variance, the regulations provide yet another possibility for exclusion.  The solid waste might be excluded from being considered a "hazardous waste" if it falls under any of the exemptions listed in the next subsection of the Code, 40 CFR 261.4(b).

Most of the hazardous waste exclusions listed in that subsection are not relevant to healthcare facilities, but here are three possibilities that may apply to you:

  1. Household waste (see 261.4(b)(1))
    • Waste from university dormitories, military housing, and any residents’s housing that you may have at your facility will fall under this exclusion. 
    • However, note that only wastes normally found in a household would fall under this exclusion.
    • Note: if your facility hosts a mercury thermometer swap for the community, this would be household waste and would qualify for the exclusion, as long as that waste is kept separate from other hospital waste.
  2. Used Freon (see 261.4(b), paragraphs (11) and (12))
  3. Samples of solid waste collected for the purpose of testing and treatability studies (see 261.4(d),(e), and (f))

Is it listed?

The RCRA regulations include four lists of materials, designated with the letters F, K, P, and U.  (The origin of the letter designations is obscure.)  If the waste you are screening appears on the any of the lists, your task is done -- it's hazardous.

What distinguishes the lists?

The F- and K-lists cover process wastes -- wastes generated from processes carried out in your facility.  The P- and U-lists cover unused commercial chemicals that are being discarded for various reasons;  for example, they may be off-specification or expired,  they may have been spilled and cleaned up, or they may be residues left in containers.

The distinction between the two process waste lists (F and K) lies in their specificity.  The K-list deals with very specific processes that are typically carried out by one manufacturing sector only, such as organic chemical manufacturing or petroleum refining.  The F-list covers general processes that might occur in a range of sectors, such as solvent use, metal finishing processes, and wood preserving.

The unused chemicals lists (P and U) differ in their degree of risk. P-listed wastes are "acutely toxic", meaning that they can cause death or irreversible illness at low doses. U-listed wastes are "toxic": they are still regarded as hazardous, but some of the more stringent regulations that apply to the P-list do not apply to U-listed wastes. It should be noted that the drug is only listed if its sole active ingredient is listed on the P or U list.

The P- and U-lists do not apply to manufactured articles that contain a P- or U-listed waste (e.g. mercury thermometers) or to products that contain more than one active ingredient.   Such wastes might still be hazardous, but their hazard classification would fall under a different category (most likely the toxicity characteristic discussed in the next section).


Healthcare facilities do not carry out manufacturing processes, and would not typically generate any K-listed materials.


The first five F-listed categories, F001 - F005, cover a range of solvents used in a variety of applications.  A healthcare facility might generate F-listed solvents such as acetone, methanol, toluene, xylene, and methylene chloride from departments such as:

  • pathology laboratory
  • histology laboratory (xylene)
  • pharmacy
  • morgue
  • maintenance shops (degreasers)

The rest of the F-list is not likely to apply to healthcare facilities.


If you are interested in reducing the hazardous waste generated in your facility, eliminating or finding substitutes for P-listed chemicals is a good place to start.  A small quantity -- one kilogram -- of a P-listed waste can cause a facility to be classified as a "large quantity generator," and to have to comply with more stringent rules as a consequence.

The P-list includes about 239 different "acutely toxic" substances, listed under about 135 different waste codes.  (Some codes cover several substances.)  HERC has identified 15 of these that you might expect to find in a healthcare facility.  They are listed below, along with their waste codes and typical uses associated with each.  The CAS numbers for these compounds can be found in the official list at 40 CFR 216.33.

Please note that our short list is not meant to be exhaustive, and also that states may impose restrictions that apply to wastes beyond those listed in the federal list.

P-listed chemicals commonly found in healthcare facilities




Arsenic Trioxide



Cyanide Salts





smoking cessation, nicotine patches, etc.

Potassium Silver Cyanide



Warfarin >0.3%


blood thinner

Physotigmine Salicylate




The U-list includes about 472 distinct materials, listed under about 247 different waste codes.  (As with the P-list, the same code can refer to several different materials.)  HERC has identified 66 of them that you might expect to find in a healthcare setting, and has listed them, along with their waste codes and typical uses, below.    The CAS numbers for these compounds can be found in the official list at 40 CFR 216.33.

Our list is not meant to be exhaustive.  States may impose restrictions that apply to wastes beyond those listed in the federal list.

U-listed chemicals commonly found in healthcare facilities




Mitomycin C



Chloral hydrate (CIV)











lice, scables




Selenium sulfide


anti-fungal, dandruff




Benzidine dichloride


pathology laboratory

Chemotherapy agents

Some chemicals used to treat cancer patients during chemotherapy fall on either the U or P lists.  These agents are often referred to by their brand names rather than the chemical designations appearing on the lists. 

Is it characteristic?

Designating hazardous materials by listing them explicitly is fine as far as it goes, but that strategy will never go far enough.  There are many more materials used in commerce than could ever be covered in a manageable set of lists.  Furthermore, some mixtures of materials can be just as hazardous as single materials, while others can be relatively benign.  Given the astronomical number of possible combinations of materials, listing is not a practical way to account for mixtures.

To cope with these possibilities, RCRA provides another set of criteria for classifying a waste as hazardous.  Whatever its composition, a waste is considered hazardous by RCRA if it exhibits any of four characteristics:

They are discussed in greater detail below.

Note:  Even if a waste has been determined to be a listed waste, it should also be evaluated to see if it also qualifies as a characteristic waste.  Additional rules may apply to it in some cases.


Ignitable wastes pose hazards because they either catch fire readily themselves, or (in the case of strong oxidizers) promote fires.

A waste is considered "ignitable" under RCRA if it is:

  • a liquid with flash point under 140oF, or
  • a non-liquid, but susceptible to vigorous burning by friction, water absorption, or spontaneous chemical change, or
  • a flammable compressed gas, or
  • a strong oxidizer

(The "flash point" of a liquid is the temperature at which the vapor above a pool of liquid will catch fire under a standard set of conditions.)

Ignitable wastes commonly found in hospitals include:

  • rubbing alcohol (if the alcohol concentration exceeds 24%)
    • certain mouthwashes including Listerine' fall into this category
  • paregoric
  • methanol
  • silver nitrate
  • certain topical preparations, such as
    • Cleocin T topical solution
    • Erythromycin topical solution
    • Retin A gel
    • collodion based preparations
  • certain injectable materials

The regulations covering the ignitability characteristic can be found in Title 40 of the Code of Federal Regulations, Part 261, Section 21 (40 CFR 261.21).


Corrosive wastes include liquids with pH less than 2 or greater than 12.5, or that corrode steel faster than a quarter-inch per year at 55oC.

Examples of corrosive wastes occurring in hospitals include concentrated solutions of acetic acid or sodium hydroxide (lye).

The regulations covering the corrosivity characteristic can be found in Title 40 of the Code of Federal Regulations, Part 261, Section 22 (40 CFR 261.22).


Reactive wastes include:

  • materials that generate toxic gases in contact with water
  • wastes that contain cyanide or sulfide and can release toxic gases in contact with strong acids or bases
  • explosive materials, or materials that are explosive when heated

Reactive wastes that may be found in hospitals include:

  • lithium-sulfur batteries
  • dry picric acid
    • explosive when dry -- should be handled with extreme care
    • may be found in histology laboratories
    • a component of the tissue preservative Bouin's Solution
  • nitroglycerin formulations (see the HERC Pharmaceuticals page for more information on nitroglycerin)
  • ethylene oxide


The RCRA sense of toxicity is somewhat indirect.  The concern is not so much with the toxic properties of the wastes themselves as with the extent to which toxic materials can leach out of the wastes if they are exposed to water in the environment.

To measure this potential, the rules specify a test called the Toxic Characteristic Leaching Procedure, or TCLP (EPA Method 1311).  The test is designed to give some indication of how readily various materials would tend to leach into groundwater if the waste were placed in a landfill.  One form of the test involves subjecting the waste to a mild acetic acid solution (about the strength of household vinegar) at room temperature for 18 hours.  The solution is then tested for the presence of any of the so-called "D-listed" chemicals.  For each of the chemicals, the RCRA rules specify a threshold level (concentration).  If any of the chemicals is present in the solution at a concentration above its threshold level, the waste is considered a toxic hazardous waste.

This link will take you to the most recent available version of the complete D-list.

Examples of hospital wastes that are considered by RCRA to have the toxicity characteristic include:

  • mercury
  • mercury compounds, such as thimerosal, used as a preservative in vaccines
  • phenylmercuric acetate
  • arsenic compounds
  • barium compounds
  • certain compounds containing other metals, including
    • chromium
    • cadmium
    • selenium
    • silver
  • chloroform
  • m-cresol
  • Lindane

Is it a mixture?

If a hazardous waste and a non-hazardous waste are mixed, the resulting mixture may inherit the hazardous classification.  The rules are different for listed and characteristic wastes.

  • Mixing in any amount of a listed waste will cause the mixture to be considered hazardous.
  • Mixing in a characteristic waste will cause the mixture to become hazardous only if the mixture itself exhibits the characteristic.

There are various exceptions and exemptions -- see, for example, the RCRA Orientation Manual listed in the More Resources section for additional information and references.

Is it derived from a hazardous waste?

Similar rules apply to wastes that are derived from listed or characteristic hazardous wastes as residues from waste treatment processes.  Since most healthcare facilities are not hazardous waste Treatment, Storage, and Disposal (TSD) sites (and thus should be sending all hazardous wastes to a licensed TSD facility), this consideration is unlikely to apply to them.

More resources

Related EPA Policy Memos

The definition of "solid waste" appearing above can be found in the US Code.  A different definition appears in the Code of Federal Regulations 40 CFR 261.2.   The US Code contains the text of laws passed by Congress, while the Code of Federal Regulations contains the text of rules written by executive agencies. The former is the definition most frequently cited by EPA.

RCRA Orientation Manual https://www.epa.gov/hwgenerators/resource-conservation-and-recovery-act-rcra-orientation-manual

©2015 Healthcare Environmental Resource Center