1.2 When is a Waste Hazardous?

Hazardous waste is a very specific term that is defined by EPA. EPA groups hazardous waste into two categories: 

  • characteristic waste (physical properties) and 
  • listed waste (specifically identified by technical name). 

EHS also collects chemical waste that may not be defined by EPA as hazardous, but presents a hazard significant enough to warrant handling as a hazardous waste.

General Characteristic Waste

Waste exhibiting any of these characteristics is hazardous.

1. Ignitability (EPA code D001)

  • Liquids that have a flash point less than 140° F (60° C.), e.g., xylene, acetonitrile, ethanol, toluene, paint thinner, methyl ethyl ketone.
  • Solids capable of causing fire by friction, absorption of moisture, or spontaneous chemical change and when ignited burn vigorously and persistently to create a hazard, e.g., picric acid, sodium dithionite.
  • Flammable compressed gases, e.g., hydrogen, ethylene, methane.
  • Oxidizers: substances that yield oxygen readily to stimulate combustion, e.g., potassium permanganate, sodium chlorate, sodium nitrate.

2. Corrosivity (EPA code D002)

  • Aqueous solutions with pH equal to or less than 2 or greater than 12.5.
  • Liquids capable of corroding steel at a specified rate and temperature.

3. Reactivity (EPA code D003)

  • Substances that react with water violently, or produce toxic gases or explosive mixtures with water, e.g., potassium, sodium, and sodium hydride.
  • Substances that are normally unstable or explosive, e.g., phosphorous.
  • Chemicals containing cyanide or sulfide that generate toxic gases when exposed to pH between 2 and 12.5, e.g., potassium cyanide, sodium sulfide.

4. Toxicity (EPA code D series D004 thru D043)

  • Materials that contain certain heavy metals above regulated levels, e.g., silver, cadmium, mercury, arsenic. (Appendix I)
  • Materials that contain certain organic constituents, mainly solvents and pesticides, above regulated levels, e.g., benzene, chloroform. (Appendix I)

Specifically Listed Waste

EPA specifically lists approximately 500 chemicals as hazardous waste.

  • EPA P List (P coded), acutely toxic chemicals (Appendix II).
  • EPA U List (U coded), toxic chemicals (Appendix III).
  • EPA F List (F coded), wastes from non-specific sources (Appendix IV).
  • EPA K list (K coded), wastes from specific sources (Appendix V).

Used Oil

Used oil is an EPA regulated material. Regulations direct that used oil should be recycled.

Universal Wastes

EPA also regulates a group of waste materials that are both hazardous to the environment and commonly found in industry as well as households. Because the materials are common, they are known as Universal Waste. Items that are Universal Waste include:

  • Mercury containing instruments such as thermometers, barometers, thermostats.
  • Fluorescent lamps that contain mercury vapor.
  • Batteries that contain hazardous materials such as NiCad, lithium and lead-acid batteries.

Other Chemical Waste

There are many other chemicals that present a hazard to human health and the environment but are not specifically regulated by EPA under RCRA. Some items that are not hazardous to human health or the environment are simply prohibited from disposal at the local landfill. These include such things as:

  • Ethidium bromide and ethidium bromide gels.
  • Carcinogens, mutagens, teratogens.
  • Pharmaceuticals.
  • Pesticides and herbicides.
  • Aerosol cans.
  • Latex paints.

See Section 1.8 of this manual for more information on disposal of specific types of waste.