Anatomy, Physiology and Human Biology

Health and safety

The cryostat's sharp microtome blade presents a cutting hazard to the user.

Since the cryostat is also an expensive, precision piece of equipment, for reasons of both safety and good work practice, all users of the cryostat are given an induction on its use prior to working independently.

In addition to this, the cryosectioning of fresh human tissue, which may contain biological hazards, requires the following appropriate safety procedures.

These procedures for the cryosectioning of fresh human tissue in the School of Anatomy and Human Biology are based on previous experience, consultation with the UWA Health and Safety Office, an inspection of current cryosectioning procedures at the PathCentre and an inspection of our procedures by the UWA Biological Safety Officer.

  1. Procedures
  2. Waste disposal, cleaning, disinfecting
  3. In case of accident

Procedures

  • Immunisation: Hepatitis B Immunisation is recommended for all staff and students who handle human blood and body tissue.
  • Storage: Samples are stored at -80 degrees, in capped tubes and appropriately labelled according to the regulations for storage of fresh human tissue.
  • Signage: A sign stating "Care: Human Tissue Sectioning in Progress, Do Not Touch" is placed on the cryostat while this work is in progress. In addition, a sign informing users that human tissue is cut on this cryostat is permanently displayed.
  • Booking: The cryostat is booked for the whole day once this procedure has begun to allow sufficient time for sectioning and cleaning and disinfecting on completion. Therefore, other users do not use the cryostat until the next day.
  • Transporting samples: Small samples are transported into the Histology Laboratory, kept cold on dry ice or frozen ice brick, and contained in a closed container such as a small esky. Flasks containing liquid nitrogen can also be used.
  • Cuts or abrasions: If the user has any cuts or abrasions these must be covered with a non-porous, waterproof dressing.
  • Gloves: Disposable, water-impermeable gloves must be worn.
  • Lab coat: A disposable lab coat must be worn.
  • Face shield: A face shield must be worn to prevent blood or body fluids/substances entering the body through mucosal contact, such as splashes of body substances to the mouth, nose, eyes or non-intact skin.
  • Cryostat number 2: The newer Leica CM3050S cryostat is to be used for human tissue cutting so this work is confined to one machine.
  • Cutting procedure: At every opportunity close the glass sliding window as this not only helps keep the temperature and humidity low for better sectioning, it is also safer as the specimen and blade are shielded from the user.
  • Plastic covers and aluminium foil are used inside the cryostat chamber to help prevent small tissue pieces lodging where they are difficult to remove.
  • Specimen chucks are isolated solely for human sectioning and stored separately from the regularly used chucks.
  • Sectioning equipment: Only the equipment necessary – such as brushes and forceps – for this work is placed inside the cryostat chamber. This collection of instruments is set aside exclusively for human tissue sectioning.
  • Cryostat sections must be labelled "Human" on each microscope slide and transported in a labelled slide box or slide tray.
  • Cryostat Day Book is filled out indicating date and the user cryosectioning fresh human tissue.

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Waste disposal, cleaning, disinfecting

  • Blades and microscope slide disposal: On completion of your work, the microtome blade (together with any other blades or sharps) are carefully removed and disposed of in a small yellow medical sharps waste container. Any unwanted microscope slides with tissue sections are also disposed of in this container, which is then closed and placed in the large yellow biological waste bin for incineration.
  • Waste disposal: All sectioning waste and the aluminium foil is removed from the cryostat and placed in the Biological Contaminated Waste For Autoclaving waste bag and labelled "Human Waste", which is then autoclaved as soon as possible and placed in the yellow biological waste bin for incineration. Any disposables such as gloves, tissues, paper towels, disposable gown or fluid shields are also disposed of in this way.
  • Cryostat chamber cleaning / disinfecting: The cryostat chamber, microtome, sample holder and any equipment are thoroughly cleaned with 70 per cent ethanol. Waste ethanol is disposed of down the flushing sink. Once the chamber has dried, the microtome, sample holder and chamber equipment are thoroughly sprayed with Cryofect and left to soak for at least 15 minutes before wiping off with tissues, which are disposed of as for waste disposal above. Cryofect is a Leica product specifically manufactured for the disinfecting of cryostats. Cryofect contains 72 per cent ethanol and 0.16 per cent chlorhexidindigluconat (see reference at bottom of page).
  • Equipment cleaning: The brushes, forceps, thermal block, chucks etc. all need to be soaked for at least 20 minutes in 70 per cent ethanol before being thoroughly cleaned with water and detergent. All autoclavable items are also autoclaved.
  • Hand washing: As per normal procedures, wash your hands before leaving the lab.

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In case of an accident

In the case of a cut injury or splash exposure, promptly flush the cut under running water, or in the case of a splash rinse the eyes, mouth and nose (if affected) using the eyewash tap. Pat dry, and in the case of a cut, apply a sterile dressing. Seek immediate medical advice. An accident report form must also be completed for the School.

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