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Decontamination

Decontamination is any process employed for removing and/or killing microorganisms and hazardous biological agents, removing or neutralizing hazardous chemical or ionising radioactive contamination.
The process should (i) be effective against the hazardous agent or substance (ii) ensure material or item is then safe to be handled further or safely disposed.
Decontamination processes are typically conducted in laboratories and clinical areas (termed ‘infection control’) to remove / kill biological hazards or remove hazardous chemical contamination from equipment, waste or other laboratory items but may also be required for contaminated ventilation systems (e.g. from fungal spores in a duct), drainage systems (e.g. removing hepatitis A in sewage drains) or buildings (e.g. that are contaminated with asbestos, heavy metals or ionising radiation open sources).

The COSHH Regulations, the GMO (Contained Use) Regulations, environmental, transport and hazardous waste regulations require certain hazardous or contaminated materials to be decontaminated before final disposal and before transport of contaminated materials / items.
There are different types of decontamination:

  1. Sterilisation: A process that kills and/or removes all classes of microorganisms and spores (all living organisms), thereby eliminating the risk of infection from exposure to the material.
    Sterilisation is conducted by physical and/or chemical methods such as autoclaving, dry heat, filtration, irradiation, ultrasonication or chemical fumigation.
  2. Disinfection: A process where a partial reduction (i.e. a ‘knock down’) of the risk of infection is achieved to ensure material is then safe to handle under defined conditions. A level of inactivation of microorganisms / infectious material is achieved but is not complete.

A disinfectant is typically, a chemical or a mixture of chemicals that kills infectious material / microorganisms, but generally not sporulating micro-organisms. Generally the disinfectant is liquid (e.g. chlorine based, peroxygen generating or quaternary ammonium mixtures), but can also be a gas.

Disinfection methods are also used for decontaminating surfaces after a laboratory spill of blood, microbial cultures or other hazardous biological material. Disinfection is also used to keep water systems clear of significant legionella bacteria contamination.

There are also methods which are used to prepare materials or items for decontamination:
Cleaning / Pre-cleaning: A process which physically removes foreign material, e.g., dust, soil, organic material such as blood, secretions, excretions and microorganisms or hazardous chemical contamination using water, detergents and /or mechanical action and creates effective conditions for further decontamination methods.
Sanitisation: A process that reduces microorganisms on an inanimate object to a level below that of infectious hazard e.g. dishes and eating utensils are sanitized using detergents or a laboratory surface wiped with 70% ethanol where there is minimal contamination with biological hazards. This process may also be used to reduce or neutralise hazardous chemical or ionising radiation contamination of items or surfaces.

Sterilisation and Disinfection – procedures, guidance and information:

Declaration of Decontamination [DOC 35KB]

QMUL Procedures for Working with Biological Agents and Materials [DOC 2,638KB] (sections B12 - 14) – for laboratories handling hazardous biological agents and/or GMOs - autoclaving, disinfection and fumigation.
QMUL Clinical Waste Disposal Poster [PDF 905KB] HSE Guidance  and section
Department of Health - HealthCare Technical Memorandum (for medical and laboratory equipment), (for healthcare clinical waste sterilisation)
QMUL Laboratory Chemical Solvent Biological Spill_Emergency Protocol [DOC 46KB]

QMUL Laboratory Clearance – denotes types of decontamination that may be required upon temporarily or permanently vacating a laboratory space.
Ionising Radiation sources – QMUL Policy and Guidance – includes requirements for decontamination of ionising radiation work areas and decommissioning.
HSE COSHH resources – includes decontamination of hazardous substances.
Specific training course: HS026 - Decontamination and Sterilisation (of hazardous biological agents)
Details and bookings at http://hsd.qmul.ac.uk/Training/index.html

For Advice and Assistance at QMUL, contact:
Dr Mark Ariyanayagam ext 8378 - H&S Manager (SMD) and Biological Safety Adviser (QMUL)
Steven Carter ext 3369- H&S Manager (Sc & Eng) and Radiation Protection Officer (QMUL)
Irida Gaikwad ext 8518 - H&S Adviser (Sc & Eng)
Suzanne Mason ext 6948 - H&S Adviser (SMD)

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