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How to Identify Hazardous Chemical Waste

Follow the steps below to decide if your material is a chemical waste, and if it is hazardous or extremely hazardous.

If you have an unknown chemical or can't answer a question in the steps below, contact the EH&S Environmental Management Facility, (858) 534-2753.

If the waste material has a Safety Data Sheet, and you would be reluctant to eat, drink, or wear the material, it is probably a hazardous waste per California regulations.

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1. Determine if the chemical is a "waste."

Anything that meets the following criteria is a waste and must be handled according to applicable local, state, and federal regulations. Regularly check chemical inventories for material that is:

  • Spent material
  • Unusable because it doesn't meet its required specifications
  • Past its expiration date
  • Unlabeled, and has been unlabeled for more than 10 days
  • Abandoned
  • A container that once held chemicals
  • Unwanted and intended to be discarded or recycled

2. Determine if the chemical is an "extremely hazardous" waste.

  • Check the list of Known Hazardous and Extremely Hazardous Wastes.
    • If your chemical waste is listed, follow its link to appropriate disposal procedures.
    • If your chemical waste is not listed, continue to questions below.
  • Answer the questions below.
    1. Do any of these exposure criteria apply to the material, in any species?
      • Does it have an acute oral LD50 less than or equal to 50 milligram per kilogram?
      • Does it have an acute dermal LD50 less than or equal to 43 mg/kg?
      • Does it have an acute inhalation LC50 less than or equal to 100 ppm as a gas or vapor?
    2. Has it been shown through experience or testing that human exposure to the waste or material my likely result in death, disabling personal injury or serious illness because of the carcinogenicity, high acute or chronic toxicity, bioaccumulative properties, or persistence in the environment of the waste or material?
    3. Is it water reactive?

    If you answer NO to all of them, proceed to Step 3. The material may be classified as hazardous waste according to the criteria in Step 3.

    If you answer YES to any of them, the chemical is extremely hazardous waste. Proceed to How to Store and Dispose of Extremely Hazardous Chemical Waste.

    For empty containers that once held extremely hazardous chemical wastes, read How To Store and Dispose of Hazardous Chemical Waste.

3. Determine if the chemical is "hazardous" waste.

  • Answer the questions below.

    If you answer NO to all the questions below, your chemical waste is not hazardous waste. Dispose of nonhazardous waste according to its type:

    • Solids can go in the regular trash. DO NOT attempt to dissolve powders or salts and dispose of them in a drain. Chemically contaminated solid waste includes 3 categories that are packaged differently for disposal: lab trash, dry chemicals, and sharps. Read How to Store & Dispose of Extremely Hazardous Waste.
    • Liquids can be poured down a drain, but may first require neutralizing or other conditioning. Read Sewer Disposal: What Can Go Down the Drain? for more information.

    If you answer YES to any of the questions below, your chemical is hazardous chemical waste. Proceed to How To Store and Dispose of Hazardous Chemical Waste.

    For empty containers that once held hazardous chemical wastes, read How to Dispose of Empty Hazardous Materials Containers.

  • Does the waste consist of solid reagent chemicals in a manufacturer's container?
  • Is the waste ignitable?
    • Is the flashpoint less than or equal to 140°F or 60°C?
    • Can the waste cause fire at standard temperature and pressure through friction, absorption of moisture, or spontaneous chemical changes?
    • Is the waste an ignitable compressed gas?
    • Is the waste an oxidizer?
    • Will it release oxygen when reacting with another chemical?
    • Will it react with organic materials such as oils, greases, solvents, paper, cloth, wood, etc., to ignite?
  • Is the waste corrosive?
    • Is it a liquid with pH less than or equal to 2, or greater than or equal to 12.5?
    • Is it a solid with pH less than or equal to 2, or greater than or equal to 12.5 when mixed with an equal weight of water?
    • Will it aggressively corrode steel?
    • Will it destroy living tissue?
  • Is the waste reactive?
    • Is it normally unstable or subject to violent change?
    • Does it react violently with water by forming potentially explosive mixtures or toxic gasses, vapors, or fumes?
    • Is it a cyanide- or sulfide-bearing waste that can create toxic gasses, vapors, or fumes when exposed to pH conditions between 2 and 12.5?
    • Can it detonate or explode when decomposing at standard temperature and pressure, when subjected to a strong initiating source, or when heated under confinement?
  • Is the waste toxic? (Toxicity measures apply to all species.)
    • Does it have an acute oral LD50 less than 2,500 milligrams per kilogram?
    • Does it have an acute dermal LD50 less than 4,300 mg/kg?
    • Does it have an acute inhalation LC50 less than 10,000 ppm as a gas or vapor?
    • Does it have an acute aquatic 96-hour LC50 less than 500 milligrams per liter?
    • Has the material shown through experience or testing to pose a hazard to human health or the environment because of its carcinogenicity (carcinogen, mutagen, teratogen), acute toxicity, chronic toxicity, bioaccumulative properties, or persistence in the environment?

Note: Many hazardous wastes are still hazardous at very low concentrations (less than 1%). Contact the EH&S Environmental Management Facility, (858) 534-2753, for assistance in determining if your low-concentration waste is hazardous.

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