Chemical Waste

What Is a Hazardous Chemical Waste

The proper identification of regulated hazardous chemical waste or "Controlled Hazardous Waste" (Maryland uses the term Controlled Hazardous Substance as a synonym for hazardous waste) is essential to facilitate the proper disposal of those wastes.

Waste compounds or solutions that meet one or more of the following criteria or are on one of the following lists are regulated as a hazardous waste by the EPA and the state of Maryland:

It is a solid waste that exhibits one or more of the hazardous waste characteristics for:

  • Ignitability
    • A liquid, other than an aqueous solution containing less than 24 percent alcohol by volume, and has a flash point less than 60 degrees Centigrade (140 degrees Fahrenheit); or
    • Not a liquid but is capable under standard temperature and pressure, of causing fire through friction, absorption of moisture or spontaneous chemical changes, and when ignited burns vigorously and persistently that it creates a hazard; or
    • An ignitable compressed gas as described in 49CFR 173.300 and as determined by the test methods described in that regulation; or
    • An oxidizer as defined in 49CFR 173.151
  • Corrosivity
    • An aqueous liquid that has a pH less than or equal to 2 or greater than or equal to 12.5; or
    • A liquid that corrodes steel at a rate greater than 6.35 mm per year at a temperature of 55 degrees Centigrade (130 degrees Fahrenheit) as specified in the appropriate test method.
    • Reactivity
    • Any hazardous material that is normally unstable and readily undergoes violent change without detonating; or
    • It reacts violently or forms potentially explosive mixtures with water; or
    • Any cyanide or sulfide-bearing waste that when exposed to pH between 2 and 12.5, can generate toxic gases, vapors or fumes in a quantity sufficient to present a danger to human health or the environment; or
    • It is capable of detonation or explosive reaction if it is subjected to a strong initiating source or if heated under confinement; or
    • It is readily capable of detonation or explosive decomposition or reaction at standard temperature or pressure; or
    • An explosive as defined in 49CFR 173.51, 49CFR 173.53, or 49CFR 173.88.
    • Toxicity  
      • The criteria for toxicity may be fulfilled if one or more of the following EPA-regulated toxic chemicals are present in a solution or compound at a concentration at or above the specified regulatory level.
      • It is listed as a hazardous waste from discarded commercial products, off-specification species, container residues, and spill residues (P & U Listed Wastes)
      • It is listed as a hazardous waste from non-specific sources (F Listed Wastes)
      • It is listed as a hazardous waste from specific sources that include primarily industrial sources (K Listed Wastes).

      Labeling Chemical Waste Containers and Quicklinks

      To comply with applicable federal and state regulations, every hazardous waste container must be tagged or labeled properly using the Hazardous Waste Labels furnished by EHS the instant that the material inside the container is determined to be a waste.

      Each waste container must be indelibly labeled with the following:

      1. The words "Hazardous Waste"
      2. [New requirement as of May 2021] Identify the waste characteristic, either by checking the box(es) on the template provide, or writing in the characteristic(s) by hand. Waste characteristics include: Reactive, Toxic, Ignitable, and/or Corrosive.
      3. The estimated chemical concentrations (% by volume) of the wastes in the container. Concentrations must total 100%.
      4. The name of the Principal Investigator.
      5. Room Number and Building the waste is being removed from.
      6. A phone number for a contact person.
      7. The date waste was initially placed into the container. When waste is moved from a Satellite Accumulation Area to a 90 Day Accumulation Area, the original date must be deleted and the date the waste was moved to the 90 Day Accumulation Area be applied.

      NOTE: EHS has preprinted labels available. To request blank labels, call (410) 706-7055. If you are not using the template provided on this page, all the information requested above must be written clearly and in English. 

      If the waste is packaged in its original container without any other wastes and the exact chemical contents are listed on the label under "Ingredients", add the words "Hazardous Waste", the building and room number where the waste is to be picked up, and the date when you determined this was expired, no longer wanted, or unusable. 

      Labels must not contain abbreviations, chemical formulas or trade names.

      Segregation of Waste Chemicals

      PURPOSE: To assure safe storage and segregation or waste chemicals

      DATE OF ISSUANCE: 2/28/97 

      The proper segregation of waste chemicals is essential to promote safe storage of those chemicals as well as to facilitate the economical disposal of the chemicals. The Environmental Protection Agency (EPA) has published a list of potentially incompatible wastes, waste components, and material along with the harmful consequences of mixing those materials together. This list does not include every possible hazardous chemical reaction but should be used as a guide in packaging and storing these materials. The Group A and B incompatible chemicals list indicates the potential consequences of the mixing of a Group A material with a Group B material. These compatibility listings should not be the only information used when packaging or accumulating waste chemicals. Pay close attention to any waste characterization data you receive on material reactivity and compatibility. Safety Data Sheets (SDSs) provide recommendations on the conditions for safe storage of any chemical, including any incompatibilities, under Section 7:  Handling and Storage. 

      Other Chemical Waste Categories

      These additional chemical waste materials may be turned in to EHS by completion of the online chemical waste removal request form.

      Mercury and Mercury-Containing Compounds and Instruments 

      Environmental Health and Safety ensures the proper disposal of all mercury and mercury-containing compounds and instruments. Mercury and mercury-containing compounds and instruments should be segregated into the following six categories and given to the EHS for disposal:

      Raw Liquid Mercury:

      Should be kept in a sealed, rigid, plastic or glass container with as little debris as possible.

      Mercury Contaminated Glassware and Broken Thermometers:

      Should be kept in a sealed, rigid, plastic or glass container.  Organic matter should not be included with the glassware. 

      NOTE:  There should be as little free-flowing mercury as possible in the container.  Free flowing mercury should be placed in a raw liquid mercury container.

      Mercury Contaminated Organic Matter (paper, plastic, cotton, etc.):

      Should be kept in a sealed, rigid, plastic container. This container can contain inorganic matter but should be kept to a minimum.

      NOTE: The total amount of mercury in the debris cannot exceed 1 pound and there must be NO free flowing mercury in the container. Free flowing mercury should be placed in the raw liquid mercury container.

      Mercury Spill Clean-Up:

      When cleaning up a mercury spill, use zinc based mercury absorbent powers only. Please DO NOT use sulfur. Explosions have been known to occur when the material in the zinc-based powder and the sulfur are mixed together. The clean-up material should be kept in a sealed, rigid, plastic or glass container. Do not mix the clean-up material with any other material. EHS can be called in to respond to a mercury spill.

      Mercury Compounds and Mercury Solutions:

      Are best kept in a sealed, rigid, plastic or glass container. If possible, do not mix with any other material and keep each compound or solution separate from each other.

      Mercury-Containing Instruments/Thermostats/Switches:

      Remove the mercury-containing component from the instrument/thermostat. If the component can be reduced to a glass constituent containing only mercury, it can be placed directly into a Mercury Contaminated Glassware container. Otherwise, place the component into its own sealed, rigid plastic, or glass container.


      Any off-specification or out-of-date pharmaceuticals should be turned into EHS for disposal.


      Many types of batteries contain heavy metals that are regulated by the EPA.

      The following batteries when spent should be turned in to EHS: lead acid, nickel cadmium, mercuric oxide, silver oxide, and lithium.

      Used Oil  

      Used oil whether generated by laboratory activities or facility operations should be turned in to EHS for disposal. Notify EHS of any oil that is contaminated with PCBs or chlorinated refrigerant oil. Never mix uncontaminated oil with oil that contains PCBs or chlorinated refrigerant oil.

      Household Cleaning Supplies 

      Many household cleaning supplies used on campus contain active ingredients that may make them corrosive, toxic, or flammable.

      Toner Cartridges 

      Many toner cartridges can be refurbished and used again. Check with the manufacturer of the toner cartridge to see if they will accept them back or know of a company that specializes in re-manufacturing of the toner cartridges. Any non-returnable toner cartridges should be turned in to EHS.

      Ethidium Bromide  

      Ethidium bromide gels and debris (contaminated paper and plastic) can be placed in a bio-hazard burn box. Turn in all solutions containing ethidium bromide.

      Photographic Chemicals 

      Any photographic processing system currently not equipped with a silver recovery unit should turn in silver contaminated photo-fixer to EHS.


      All outdated, off-specification, or spent liquid paint and liquid paint wastes should be turned in to EHS for disposal.

      Unknown Chemical Waste

      Faculty and staff must make every effort to provide an accurate description of all chemical waste. Unknown chemical waste presents a serious problem for EHS. Without an accurate description, chemicals cannot be disposed of in a safe manner. Disposal companies will not accept chemical waste without an accurate description and analysis of unknowns can easily cost up to several hundred dollars.

      When a laboratory determines that it has a chemical waste material that it cannot identify, contact EHS. We will assist you in making a proper identification of the chemical. In cases where together we cannot identify the chemical, a sample of the unknown will be sent to an analytical laboratory for identification.

      In the past, EHS has assumed the cost of the identification of many unknowns. Due to the high cost of analysis, EHS does reserve the right to institute a charge-back program for the charges associated with the analysis.