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Categories of Dangerous Waste

Identify Categories of Dangerous Waste

Identifying waste as a "dangerous waste," subject to or exempt from the Dangerous Waste Regulations and applying a waste code is called waste designation. There are three categories of dangerous waste. These categories are important for applying the proper waste code to each waste or waste stream. 

All Dangerous Wastes subject to regulations are Listed, Characteristic, or State Criteria Wastes. Two smaller subsets of dangerous waste, "Extremely Hazardous Wastes" and "Acutely Hazardous Wastes" have special regulations attached to them.

Listed Wastes
The Dangerous waste regulations contain lists of chemicals and specific waste streams. These lists are used to identify dangerous wastes, and are divided into two main categories:

  1. Discarded chemical products are unused commercial chemical products containing only one sole active ingredient. There are two lists of discarded chemicals:
    1. Acutely hazardous “P” listed chemicals are stringently regulated
    2. “U” listed chemicals are less stringently regulated
  2. Waste streams listed by source. There are three lists of waste streams from sources:
    1. “F” listed wastes are from non-specific sources
    2. "K” listed wastes are from specific types of industries and manufacturing processes
    3. “WPCB" Washington State-only sources. Includes discarded transformers, capacitors or bushings containing polychlorinated biphenyls (PCB) at concentrations of 2 parts per million or greater. Washington State regulates PCBs much more stringently than EPA.

Characteristics Wastes


General Definition (see WAC 173-303-090 for full description)

Ignitable If a liquid, has a flashpoint of 140 degrees Fahrenheit or less. If a solid, will ignite and burn vigorously through friction, absorbtion of moisture or spontaneous chemical changes. Compresses gases and oxidizers are also classified as ignitable under certain conditions.
Corrosive If a liquid, has a pH less than 2 and greater than 12.5, or it is a liquid and corrodes steel at a specified rate. If a solid or a semisolid it has a pH less than 2 or greater than 12.5 (solid corrosive are a Washington state-only waste).
Reactive Could explode, reacts violently or produce harmful vapors.
Toxicity A solid waste exhibits the toxicity characteristics if an extract of a representative sample (obtained by the toxicity characteristics leaching procedure (TCLP)) contains regulated levels of chemicals listed at WAC 173-303-090(8). Currently 40 chemicals are listed, including heavy metals, pesticides, solvents and other organics.

Identify (Designate) Dangerous Waste describes methods for determining if wastes have characteristics that might place them in this category of waste.

Washington State Criteria Wastes
The Washington State dangerous waste regulations are more stringent than the federal hazardous waste rules. Washington State regulates additional toxic and persistent dangerous wastes according to criteria. "Dangerous waste criteria" is found at WAC 173-303-100 in the Dangerous Waste Regulations. This section describes the standards for designating waste as a state-only toxic or persistent criteria waste.

Toxic Criteria Waste
Toxic criteria waste are regulated because testing shows they are lethal to fish or animals. A generator can have a lab test his waste using a bioassay test. More commonly, generators will use information from toxicity databases. These databases show results from testing specific chemicals on animals or fish. Highly toxic chemicals will cause mortality at low concentrations. The generator must know the concentration of the specific chemicals found in their waste in order to calculate if their waste is a state toxic waste

Persistent Criteria Wastes
Persistent Criteria Wastes linger in the environment for a long time. Two groups of Persistent Criteria Wastes are highlighted in the Dangerous Waste Regulations, Polycyclic Aromatic Hydrocarbons (PAHs) and Halogenated Organic Compounds  (HOCs).

The regulations list 20 hazardous chemicals identified as PAHs, having hydrocarbon molecules fused with two or more benzene rings.  Wastes with more than 1% PAHs are a dangerous waste.    

HOCs are any organic (carbon-based) compound which includes at least one atom of either bromine, chlorine, fluorine, or iodine bonded directly to a carbon atom.  A common HOC is dry cleaner perchloroethylene solvent.

State Criteria Wastes and Codes


Waste Code

Extremely Hazardous Toxic Criteria Waste or Dangerous Toxic Criteria Waste based on testing, book designation or the generator's knowledge of their waste. (This is not the EPA Toxicity Characteristic Leaching Procedure or TCLP test.) WT01 or WT02
Extremely Hazardous Persistent Criteria Waste or Dangerous Persistent Criteria Waste based on the total concentration of Halogenated Organic Compounds (HOCs) WP01 or WP02
Extremely Hazardous Persistent Criteria Waste based on the total concentration of Polycyclic Aromatic Hydrocarbons (PAHs) WP03

Related information

Chemical Testing Methods for Designating Dangerous Waste, Ecology Publication 97-407

Which Rules Apply? discusses generator status based on the amounts and types of waste generated.

Identify (Designate) Dangerous Waste describes methods for determining if wastes have the characteristics that might place them in this category of waste.

Hazardous Waste: More Common Than You Think is a basic Ecology Publication describing dangerous waste and where it might be found.

Checklist for Hazardous Waste Generators is an Ecology checklist that will help determine if a business produces dangerous wastes. It summarizes generator responsibilities.

Report Waste briefly discusses waste codes need for Annual Dangerous Waste Reporting.

Designation of Dangerous Waste  is at WAC 173-303-070 of the Dangerous Waste Regulations.

Excluded Categories of Waste is at WAC 173-303-071 of the Dangerous Waste Regulations.

Procedures and bases for exempting and excluding wastes is at WAC 173-303-072 of the Dangerous Waste Regulations.

Dangerous waste characteristics is at WAC 173-303-090 of the Dangerous Waste Regulations.

Dangerous waste criteria is at WAC 173-303-100 of the Dangerous Waste Regulations.

Alphabetic definitions list in the Dangerous Waste Regulations at WAC 173-303-040 lists PAHs under "polycyclic aromatic hydrocarbons."