Chemical Waste Disposal Procedures

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The University of Toronto manages the disposal of chemical waste through the Environmental Protection Services (Hazardous Materials) of the Office of Environmental Health and Safety. Any questions with respect to the disposal of chemical wastes should be directed to this Section at: 978-7000 or 978-4821 or email at

The following waste handling procedures are mandatory when preparing chemicals for disposal. The procedures apply to operations on all University campuses.


  1. Chemical wastes sent for disposal should not be mixed with biohazardous or radioactive wastes.
  2. Hazardous liquids must not be flushed down drains as a method for disposal. This practice is illegal and may lead to dangerous reactions and damage to the draining system as well as create a potential hazard to trades personnel working on the system. Solid or liquid waste chemicals must not be mixed with general garbage.
  3. In order to avoid explosions, fires or spills, incompatible combinations of chemicals must not be mixed in a single container (see Segregation of chemical wastes).
  4. The waste generator bears the primary responsibility for proper packaging and labelling.
  5. If the Manager, Environmental Protection (Hazardous Materials) overseeing the collection has any doubts about proper labelling or packaging techniques, waste will not be removed until it is properly prepared.
  6. Materials requiring special handling include organic peroxides, PCBs [polychlorinated biphenyls] and explosives. Before disposing these materials, consult the Co-ordinator, Hazardous Waste Management.



  1. All containers used for storing chemical waste must be sealed and undamaged. Any container not properly sealed will not be removed. (corks or rubber stoppers are not recommended)
  2. Liquid waste containers should only be filled to 70-80% capacity to allow for vapour expansion and to minimize the potential for spills occurring from overfilled containers.
  3. Container material must be compatible with the stored chemical waste [eg. hydrofluoric acid cannot be stored in glass containers].



  1. To prevent the mixing of waste which could create an incompatible reaction, all materials must be clearly identified by means of standard Chemical Waste labels provided by the Environmental Protection Services (Hazardous Materials).
  2. The following information must be provided:
    • Specific generic names of the components in the container along with approximate percentages of each component present must be listed. No abbreviations or trade mark names are to be used. Vague categories [eg. solvent waste] are not acceptable.
    • Building name, room number and individual to contact. The general hazards can be indicated by marking the appropriate boxes on the Chemical Waste Label.
  3. If the waste is not identified, the containers will not be removed.



  1. Waste chemicals should, if possible, be stored in a central waste-holding facility of the building.
  2. Should such a facility be non-existent, the chemical waste should be temporarily stored in the generator's laboratory.
  3. All safety precautions required for handling and storage of chemicals will also be observed with generated wastes.
  4. It is recommended that waste be segregated according to compatibility groups.



  1. If a building has a central waste-holding facility, the individual managing the area is responsible for scheduling collection.
  2. If chemical waste is stored in an individual's laboratory, it is the responsibility of the generator to schedule a waste collection.
  3. Chemical waste collection is arranged through the Environmental Protection Services (Hazardous Materials) at 978-7000 or 978-4821 or email at
  4. Chemical waste must not be allowed to accumulate. The frequency of collection is dependent upon the type and amount of waste generated.
  5. Waste or empty gas cylinders generally can be returned directly to the supplier. If this is not possible, contact the Environmental Protection Services (Hazardous Materials).



Waste chemicals should be stored according to the following groupings based on chemical reactivities. For any waste that cannot be classified according to these groups, the Manager, Environmental Protection Services (Hazardous Materials) [978-7000] should be consulted.

Materials requiring special handling include organic peroxides, PCBs [polychlorinated biphenyls] and explosives. Before disposing these materials, consult the Manager, Environmental Protection Services (Hazardous Materials).

Group A - Inorganic Acids and Acid Salts

  • All inorganic acids (eg. sulphuric, hydrochloric)
  • All compounds which do not liberate a gas when acidified (eg. ferric chloride, sodium sulphate).
  • Inorganic solids which are inert (eg. silica).

    Note: Perchloric acid, although an inorganic acid, is a powerful oxidizing agent and should be included in Group E.

Group B - Nitrogenated Bases, Caustics and Acid-Reactive Compounds

  • Organic and inorganic bases (eg. pyridine, amines, sodium hydroxide).
  • Elements and inorganic salts that may react with acids to liberate gaseous products (eg. potassium cyanide, ferric sulphide).

Group C - Neutral Organic Solids

  • All solid organic compounds which are neutral - no acids or bases (eg. carbon black, styrene).

Group D - Flammable Liquids, Halogenated Solvents and Organic Acids

  • All organic liquids excluding organic bases (eg. toluene, chloroform).
  • Organic acids (eg. formic acid, acetic acid).

Group E - Oxidizers

  • Any inorganic compound that assists fire (eg. hydrogen peroxide, lead nitrate).

Group F - Pesticides

  • Any compounds used to destroy or inhibit plant or animal pest such as pesticides, fungicides, insecticides etc.

Group Specials - Water and Air Reactive Materials

  • All chemicals which react to air and/or water, including fuming substances (eg. sodium - a water reactive, phosphorus - an air reactive, lithium aluminum hydride - both air and water reactive, thionyl chloride and phosphorus tribromide - fuming substances).


When preparing chemical waste for disposal, it is the generator's responsibility to ensure that incompatible chemicals are not stored in the same container. A few general examples are:

  • Oxidizers [Group E] should never be mixed with reducing agents [eg water-reactive chemicals such as sodium] or organic materials [Groups B, C and D]
  • Acid-reactive compounds [Group B] which liberate gaseous products when acidifies should not be mixed with any acid [Group A and E].
  • Organic acids [Group D] should be segregated from inorganic acids [Group A]. Generally inorganic acids are oxidizing agents while some organic acids may be either reducing agents or combustible.

Once the waste has been classified according to the chemical groups, it must be segregated to minimize the risk of mixing incompatible groups.