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Management of Mixed Liquid Radioactive Waste

If a laboratory generates a waste containing a radioisotope(s) and an USEPA Hazardous Waste, the laboratory generates mixed waste.  In regulatory terms, a Hazardous Waste is a chemical waste that exhibits at least one of four characteristics—ignitability, corrosivity, reactivity, or toxicity—or is specifically listed on one of four hazardous wastes lists developed USEPA and NYSDEC.
In general terms, Hazardous Waste is any liquid, solid, contained gas or sludge that you intend to dispose of and which has properties that make it dangerous or potentially harmful to human health or the environment if not disposed of properly.

Examples of mixed waste include: tritiated benzopyrene in ethyl acetate (a Flammable Characteristic Waste/Listed Waste), P-32 labeled GTP in chloroform (a Toxicity Characteristic Waste), and C-14 labeled acetic acid, pH<2 (a Corrosive Characteristic Waste).

If you are uncertain whether or not your laboratory generates mixed waste, please contact EH&S (include website link)


This Policy & Procedure sets forth the guidelines for mixed liquid radioactive waste management in laboratories at Columbia University Medical Center (CUMC), New York State Psychiatric Institute (NYSPI) and New York Presbyterian Hospital (NYPH). All responsible investigators and laboratory workers generating mixed radioactive waste must comply with the applicable regulatory requirements and the university policy.


This policy and procedure covers all generators of mixed radioactive waste at the CUMC, NYSPI and NYPH .


The Radiation Safety Office manages liquid radioactive waste under the Radioactive Materials Licenses obtained from the New York City Department of Health (NYCDOH) and a permit from the New York State Department of Environmental Conservation (NYSDEC). However, since mixed radioactive waste contains both radioactive isotopes and hazardous chemicals, it therefore, also comes under the guidelines of the EPA as well the Nuclear Regulatory Commission NYCDOH and NYSDEC. The Radiation Safety Office is responsible for the management of mixed liquid radioactive waste. The Environmental Health & Safety (EH&S) collaborates with the RSO in the disposal of mixed radioactive waste.


1. Liquid Waste Liquid radioactive waste (referred to hereafter as “liquid waste”) can be classified into two categories according to its constituents: aqueous radioactive waste (referred to hereafter as “aqueous waste”) and mixed liquid radioactive waste (referred to hereafter as “mixed waste”).Liquid waste may consist of a variety of chemical constituents but it must be “homogeneous” and "pourable". Although, the presence of small amounts of non-soluble materials may be unavoidable, it should not generally contain any solid materials such as pipette tips, micro centrifuge tubes, etc.

a. Aqueous Waste Aqueous waste refers to liquid radioactive waste thatmainly consists of radioactive materials dissolved in non-hazardous water solution. It should not contain any hazardous chemical. 

b. Mixed Waste The term “mixed liquid waste” or “mixed waste” refers to liquid wastes that contain both, radioisotopes and hazardous chemicals (refer to the Chemical Waste Procedures for CUMC and NYSPI for the definition of Hazardous Chemical Waste in the CUMC Health and Safety Manual). Examples of mixed waste include: tritiated benzopyrene in ethyl acetate (a Flammable Characteristic Waste/Listed Waste), P-32 labeled GTP in chloroform (a Toxicity Characteristic Waste), and C-14 labeled acetic acid, pH<2 (a Corrosive Characteristic Waste). The Responsible Investigator must determine if the waste generated by an experiment would be classified as an aqueous waste or a mixed waste. Please consult with the RSO and EH&S if the laboratory has questions to whether or not the waste is “mixed.”

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1. Liquid Waste

Segregation Liquid radioactive waste must be segregated on the basis of chemical composition (aqueous vs. mixed). The mixed waste, however, should be segregated on the basis of hazard class of the chemical present in the waste (flammable, corrosive, toxic, etc.). The RSO provides 2.5 or 5.0- gallon plastic containers for liquid waste storage, but will allow laboratories to use other containers for the storage of mixed waste as long as it is compatible with the chemical present in the mixed waste and it is approved by the RSO and EH&S.

2. Storage of Mixed Waste

The liquid waste must be stored in the laboratory at a satellite accumulation point until picked up by the RSO. The containers should not be filled more than 75 % and must remain in an upright position at all times. Each collection container must be maintained in a catch basin capable of holding the total volume of liquid in case of any leak or spill. The container must be kept closed at all times except when adding liquid waste into the container. Whenever the liquid container is moved, the cap must be tightly sealed. Scintillation vials and in-vitro vials of mixed waste should be collected and stored in containers provided by RSO. Before putting vials into a waste container, the lab personnel must ensure that vial caps are tightened. Do not put other materials into containers such as gloves, cartons, Styrofoam, etc. In addition, scintillation vials should be segregated by half-life categories.

3. Mixed Waste Management

There should be no generation of mixed wastes without the prior written approval of the RSO. If the lab is planning an experiment that could potentially generate mixed wastes, a written standard operating procedure (SOP) containing information regarding collection, storage, labeling and disposal of mixed waste shall be developed. The RI should forward a copy of SOP to RSO and EH&S for approval. Laboratories are encouraged to use non-hazardous substitute materials to minimize the generation of mixed waste, when feasible. Use small volumes of hazardous materials to minimize production of mixed waste. Do not add aqueous waste into the mixed waste. This will help in reducing the volume and disposal cost of mixed waste.   RI must store mixed waste in their laboratory and ensure that each container is properly labeled with appropriate radiation and hazardous waste labels. Pick up will be made directly from these laboratories upon written request of the RI, as follows:

a. Mixed waste containing isotopes with short half-life (half-life less than 60 days) will be stored in the laboratory for decay. Upon filling the container it must be sealed and dated by the RSO. At the end of decay period the RSO will assay the waste for radioactivity. If the activity is below the regulatory limits, liquid waste carboys will be handled by the EH&S for proper disposal.

b. For mixed waste containing isotopes with long half-life (half-life greater than 60 days), RSO will schedule for the pickup from the lab immediately prior to shipment by a licensed vendor.

4. Packaging Instructions

a. Aqueous Waste All aqueous waste should be collected and stored per RSO guidelines found in the CUMC Health and Safety Manual.

b. Mixed Waste Laboratory personnel should observe the following rules for containers of mixed waste:

  • Use separate containers for short half-life and long half-life radioactive wastes.
  • Use 2.5- or 5.0-gallon containers provided by RSO suitable for storage of mixed waste. If plastic carboys are not suitable for waste contents, approved glass bottles may be used instead.
  • Store the carboys in a secondary containment system suitable for mixed waste.
  • Ensure a "Caution Radioactive Materials" label is fixed to the outside of the carboy.
  • Record the isotope and activity of the contents of the carboy and secure or attach it to the outside of the container.
  • Secure a “Hazardous Waste” label listing hazardous chemical and percentage of each chemical on the label. Use full name of the chemical rather than formula or abbreviations (appropriate labels for hazardous waste may be obtained from EH&S and affixed prior to using it).
  • Segregate and store radioactive waste in the laboratory where it was generated according to isotope, chemical hazard class, and compatibility. Pickup will be made directly from the lab as outlined above.
  • Do not overfill containers.When the container is 75% full, complete a radioactive waste service request and a radioactive waste tracking form, and send it to the RSO.
  • Upon receipt of the above mentioned forms the RSO will contact the laboratory to make arrangements for disposal.

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Spill Control

A copy of the RSO Radioactive Spill Procedure is posted in each laboratory where radionuclides are used. In case an aqueous waste is spilled, laboratory personnel should observe procedures outlined in the RSO guidelines and inform the RSO immediately. In case a mixed waste is spilled, the lab should immediately inform both the RSO and EH&S.


The RSO provides a radiation safety training lecture that includes waste management topics. Mixed waste training lectures will be given to individual labs upon request and when necessary. All investigators and laboratory workers using radionuclides should attend the initial training class prior to working with radioactive material, and should attend refresher lectures once a year, thereafter. A schedule of radiation safety training lectures is obtainable from the RSO or its website.


The RSO is responsible for the enforcement of this policy and to provide training to researchers and staff related to the management of mixed waste.

RSO and EH&S Contact

Any questions regarding the radioactive waste management program may be addressed to the RSO.

Telephone: (212) 305-0303

Questions regarding the chemical waste management program may be addressed to the EH&S.

Telephone: (212) 305-6780

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