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Cytogenetics

Disposal

Effective waste management is a critical component of laboratory safety and regulatory compliance. The “Cradle to Grave” principle dictates that the laboratory is legally responsible for its waste from the moment it is generated until it is destroyed. Cytogenetics laboratories generate a complex mix of waste streams, requiring strict segregation of biological hazards, sharps, clean glass, and hazardous chemicals

Biohazard Waste (Regulated Medical Waste)

Biohazard waste includes any solid waste generated in the diagnosis, treatment, or immunization of human beings. In Cytogenetics, this encompasses items contaminated with blood, bone marrow, amniotic fluid, or cell cultures

  • The Container
    • Must be placed in Red Biohazard Bags: held within rigid, leak-proof containers with lids
    • Must display the universal Biohazard symbol
  • What Goes In
    • Culture Flasks: Plastic T-25 or T-75 flasks containing residual media and cells
    • Centrifuge Tubes: Plastic conical tubes used for harvest (after liquid is decanted)
    • Contaminated PPE: Gloves, aprons, or lab coats (if disposable) that have visible blood or body fluids on them
    • Consumables: Plastic pipettes, pipette tips, and Kimwipes used to wipe up minor biological spills
  • Safety Protocols
    • Do Not Overfill: Bags should be sealed when 3/4 full to prevent rupture during transport
    • Double Bagging: If the waste is heavy or wet, use two bags to ensure containment
    • No Sharps: Never throw glass or needles into a soft red bag, as they will puncture the bag and injure housekeeping staff

Sharps Disposal

A “sharp” is any device or object capable of puncturing or cutting the skin. This category poses the highest risk for percutaneous injury and subsequent bloodborne pathogen transmission

  • The Container
    • Rigid, puncture-resistant, leak-proof containers (usually red) marked with the Biohazard symbol
  • What Goes In
    • Glass Pasteur Pipettes: Cytogeneticists use these extensively for “dropping” slides. Even if unbroken, they are considered sharps because they can break easily during handling
    • Microscope Slides: Glass slides (both clean and used) are sharp. Used slides contain fixed cells; breakage can create hazardous shards
    • Scalpels and Razors: Used for mincing solid tissue (POC, chorionic villi, skin biopsies)
    • Hypodermic Needles: Used for syringe harvesting or venting culture flasks
    • Broken Glassware: Any broken glass beaker or cylinder that is contaminated with biological material
  • Safety Protocols
    • Never Recap: Never recap a needle using two hands. If recapping is necessary, use the one-handed “scoop” technique or a mechanical device
    • Fill Line: Strictly observe the “Fill Line” (usually 3/4 full). Forcing items into a full sharps container is a common cause of needle-stick injuries

“Clean” Broken Glass Disposal

Not all glass is biohazardous. To save costs and reserve sharps containers for actual hazards, laboratories use a separate stream for non-infectious glass

  • The Container
    • A cardboard box lined with a thick plastic bag, clearly labeled “Broken Glass”: (often blue and white)
  • What Goes In
    • Broken beakers, flasks, or graduated cylinders that were clean: or contained non-hazardous buffers (e.g., saline, water) at the time of breakage
    • Clean microscope slides that were dropped before use
  • What STAYS OUT
    • No Biohazards: If the glass has blood on it, it goes in the Red Sharps container
    • No Chemicals: If the glass broke while holding a hazardous chemical (e.g., a bottle of methanol), it is treated as Chemical Waste

Liquid Waste Disposal

Cytogenetics generates significant liquid waste, particularly supernatant removed during the harvest process (media, hypotonic solution, fixative)

  • Biological Liquid Waste
    • Source: Spent culture media, hypotonic solution, amniotic fluid
    • Disposal Method: Can typically be poured down the sanitary sewer (sink) ONLY IF: it is pre-treated or flushed with a disinfectant
    • Protocol: Most labs add 10% Sodium Hypochlorite (Bleach): to the liquid waste trap or suction canister. After 20–30 minutes of contact time to kill pathogens, the liquid can be poured down the drain with copious amounts of water
  • Chemical Liquid Waste (Strict Prohibition)
    • Fixative (Methanol/Acetic Acid): This CANNOT go down the drain. It is flammable and toxic. It must be collected in a satellite accumulation drum designated for “Flammable Solvents.”
    • Stain Waste: Buffer/Stain runoff containing methanol or heavy metals must be collected in chemical waste containers, not the sink

Summary of Waste Segregation

  • Soft + Contaminated: \(\rightarrow\) Red Biohazard Bag
  • Sharp + Contaminated (or Glass): \(\rightarrow\) Red Rigid Sharps Container
  • Sharp + Clean (Glass): \(\rightarrow\) Cardboard Glass Box
  • Liquid + Biological: \(\rightarrow\) Bleach \(\rightarrow\) Drain
  • Liquid + Chemical: \(\rightarrow\) Hazardous Waste Drum