How Is Hazardous Waste Listed and Categorized?

Most waste can easily be tossed into the trash and sent to the dump or recycling centers without a second thought. However, hazardous waste includes potentially toxic and dangerous chemicals that must be disposed of properly to ensure public safety. If your business creates hazardous waste, you need to learn about how hazardous waste is listed and categorized.


Much of hazardous waste is considered listed, which allows it to be separated into F, K, P, and U lists. All are considered hazardous, but waste from F and K lists is caused by manufacturing, and waste from P and U lists is unused commercial chemicals.

F and K Lists

All F- and K-listed wastes are manufacturing process waste. F-list wastes, however, do not come from a specific source. In other words, they may come from any manufacturing process. Examples of F-list waste include spent solvent waste, electroplating waste, wood preserving waste, and wastewater treatment sludge waste from a petroleum refinery.

K-list waste is from a specific source, which means it comes from manufacturing specific products. Common examples of K-list waste comes from pesticide manufacturing, ink formulation, veterinary pharmaceutical manufacturing, and iron and steel production.

P and U Lists

P- and U-listed wastes only include commercial chemicals that have been unused but need to be disposed of. One reason you may need to dispose of unused commercial chemicals is if they are expired. Similarly, if the chemicals have been spilt, they should be disposed of as P- or U-list waste.

The difference between P-list and U-list waste is the toxicity. P-list waste is considered more toxic than U-list waste.


Some waste is unlisted, and in order to organize the waste, the EPA has four characteristics, including ignitability, corrosivity, reactivity, and toxicity.


The first characteristic used to measure the danger of a hazardous material is ignitability. This type of waste can quickly catch on fire and includes liquid that releases fumes at 140 degrees Fahrenheit, such as gasoline.

This type of waste also includes solids that may spontaneously combust, such as metal powders or activated charcoal. Ignitable compressed gases and oxidizers are also considered highly ignitable.


Corrosivity usually refers to acidic waste, including inorganic acids (such as hydraulic acid), organic acids (such as lactic acid), and alkaline compounds (such as hydroxides). These substances need to have a pH of less than 2 or higher than 12.5 to be considered acidic.

As an added insult, corrosive waste may actually be able to destroy the container in which it is housed, making it potentially hard to store for long periods of time.


Reactive wastes are those that have the potential to be dangerous and explosive. Some become dangerous when exposed to water, such as anhydrous metal salts, alkali metals, and metal powders. Some compounds even cause explosions when exposed to water, such as calcium carbide and metal hydrides.

Reactive wastes may also include unstable compounds that can change without detonating. This includes diethyl zinc and organometallic gases. Finally, compounds that could create explosive reactions include dry picric acid and trinitro compounds.


Toxic waste refers to any poisonous substance that can affect groundwater, which can affect the environment and humans. Heavy metals included in this category are arsenic, lead, mercury, and silver.

Many pesticides are also considered toxic as well as common organic chemicals like chloroform, vinyl chloride, and cresols.

If you have hazardous waste, it needs to be disposed of properly. Failure to comply with federal rules and regulations can result in serious punishment for you and your entire business. If you would like to learn more about waste removal, contact us at City Disposal today.

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