Properly handling hazardous chemical waste is important to environmental and occupational health. The following waste categories are designated as hazardous:

  • Toxic
  • Flammable
  • Oxidizers
  • Corrosive
  • Reactive
  • Persistant
  • Carcinogenic

You must label your waste with a hazardous waste label and pickup is scheduled through UW EH&S.

*NOTE* As of November 2019, UW EH&S has updated the Hazardous Waste labels to comply with EPA's Hazardous Waste Generator Improvements Rule. Please ensure that you are using the NEW labels.


New Hazardous Waste Label

Remember to only combine compatible wastes and use suitable waste containers. If you are not sure about the compatibility of two wastes, keep them separate!


Toxic waste at the University of Washington is classified as having an Equivalent Concentration ≥ 0.001%. The equivalent concentration is calculated based on the toxicity category of each of a solution's individual components. To determine this, you must consult the safety data sheets of each toxic component.

Equivalent Concentration equals the summation of the toxic categories divided by factors of ten.

Acute toxicity hazard symbol

Poison or very acutely toxic hazard symbol







Flammable wastes are those that have a flashpoint <60°C. When flammable components are in solution utilize available flash point curves to determine flammability.

Flammable Hazard Symbol


For the purpose of hazard labelling, oxidizers are chemicals that can cause or contribute to the combustion of another material.

Oxidixer hazard symbol







Corrosive wastes are those with a pH <5.5 or >12 or others that are inherently corrosive. Acidic and basic non-toxic solutions can be treated and disposed of down the sink if you have proper authorization from UW EH&S.

Corrosive Hazard Symbol


Consult a chemical's safety data sheet to determine reactivity and any incompatible conditions.

Explosive hazard symbol






These are wastes that are not readily degraded in the environment and include solutions containing Halogenated Organic Compounds (HOCs) >0.01% or Polycyclic Aromatic Hydrocarbons (PAHs) >1%.

Environmental toxicity hazard symbol






Carcinogenic and Chronic Health Hazards

Where data is available, known, probable, or suspected carcinogens should be handled as hazardous waste. For wastes with chronic health hazards, consult an EH&S specialist for disposal recommendations.

Chronic health hazard symbol