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Mixed hazardous waste is waste which falls into two or more different categories of hazardous materials. Examples include radioactive contaminated phenol/chloroform, or blood labeled with a radionuclide. Special disposal procedures must be followed with mixed wastes to prevent handlers from receiving an exposure from one hazard while treating another. Also, disposal regulations require different disposal methods for mixed wastes.
Whenever possible, it is best to avoid generating mixed wastes. When a mixed waste must be generated, follow the guidelines under the appropriate heading listed below.
Biohazardous (infectious) liquid contaminated with radionuclides of an activity that can be sewered according to Section 7.3, Absorbed Aqueous Liquid (AAL) Radioactive Wastes, should be disinfected with Clorox and flushed down the sewer with running water. See also Section 8.4, Disinfecting and Disposing of Biohazardous Liquids within the Lab.
If the biohazardous waste contains radionuclides greater than sewerable amounts, or if the biohazardous material is too bulky to be properly disinfected within the lab, the material must be treated as a radioactive waste. Package the material according to radioactive waste procedures and identify the biohazardous agent. If the lab believes the biohazardous material should be autoclaved, please call EH&S for assistance.
Note: Do not send radioactive biohazardous waste to the autoclave for sterilization.
When possible, disinfect the biohazardous part of the mix and then dispose of it as chemical waste. Hazardous chemical biohazardous waste cannot be autoclaved. If the chemical is incompatible with chemical disinfection methods, call EH&S for disposal information.
For instructions on scintillation fluid and vials, see Section 10.3.3, Scintillation Fluid.
Hazardous chemicals mixed with radionuclides cannot be disposed of with the regular Hutchinson Center radioactive waste. A radioactive hazardous chemical waste is treated or allowed to decay to insignificant levels and ultimately disposed of as hazardous chemical waste. Do not absorb hazardous chemicals mixed with radionuclides. Keep them as freestanding liquid.
Hold radionuclides from Group I mixed with hazardous chemicals in the lab for decay for 10 half lives. Then treat as chemical waste, following the appropriate disposal instructions in Section 4.
Radionuclides from Groups II, III, and IV mixed with hazardous chemicals should be prepared for EH&S collection. Do not absorb; keep as freestanding liquid. Always label this waste with both a complete chemical waste label and a complete radioactive waste label, as described in Section 4.3.4 and Section 7.6.
Except for National Diagnostics Ecoscint, scintillation fluid containing radioactive material is a type of "mixed" waste in that it is both a radioactive waste and a chemical waste. The only cocktail considered to be non-hazardous in Washington State is:
National Diagnostics Ecoscint
This scintillation fluid may be disposed of into the sewer, when the instructions in Section 7.5, Sewering Aqueous Radioactive Wastes are followed. No other scintillation fluid should be assumed to be non-hazardous without written documentation from the Hazardous Waste Manager or Radiation safety officer (x4866). Most scintillation fluid containing radioactive materials are considered mixed waste and must be disposed of as described below.
Do not absorb hazardous chemicals even if they contain radioactive material. Keep them as freestanding liquid.
Hazardous chemicals containing radioactive material must be accumulated in a bottle and left as freestanding liquid. Do not absorb scintillation fluids, even sewerable fluids, into sand, and never dispose of non-empty scintillation vials in dry solid waste boxes.
Liquid scintillation vials containing waste scintillation fluid may be emptied into a large container. Do this inside a chemical fume hood while wearing gloves and a lab coat. Store accumulated waste in a flammable storage cabinet until ready for EH&S collection.
Emptied vials should be discarded in the Dry, Solid Radioactive Waste container.
If vials are not emptied by the lab, package for EH&S collection by placing them inside a cardboard box lined with a plastic bag. The box is a necessary precaution to prevent injury from broken vials. Packing materials are provided by EH&S. The outside package should be labeled as described in Section 7.6, Labeling Radioactive Waste. Plates containing scintillation fluids should be disposed of in the same manner, but separately from vials.