Disinfection & waste disposal

General

All biological material (liquids and contaminated solids) must be inactivated before release from departmental facilities. Typical methods used include disinfection and sterilisation by autoclave treatment.

Disinfection

The use of chemical disinfectants, normally in the form of proprietary products specifically for use in laboratories, is a widespread and important control technique in biological laboratories. Laboratories handling microorganisms and other hazardous biological materials should routinely use chemical disinfection to decontaminate surfaces and equipment, and prevent microbial growth in spent culture fluids etc.

If possible, the number of different disinfectants used in a laboratory should be reduced to a minimum to avoid mistakes in application. Adequate information and instructions must be given to all workers to ensure they know what disinfectant to use and how to use it.

Each laboratory group must ensure there is a clear documented disinfection policy indicating suitable concentrations, contact times and applications for all disinfection requirements within the group. Guidance on the selection and use of disinfectants is given on the departmental safety website.

Chemical Disinfectants

Care must be taken to ensure that the disinfectant used is appropriate for the task in hand, and is, in fact, effective against the biohazards likely to be present. All disinfectants are by their nature hazardous to human health although the extent varies considerably. Some disinfectants, such as formaldehyde and glutaraldehyde, have irritant and toxic properties, are extremely hazardous and carry a risk of respiratory and/or skin sensitisation reactions. These types of chemical disinfectants must not be used as a general disinfectant in the laboratory and be employed only for specialised uses when no suitable alternative is available and subject to a strict risk assessment.

If it is necessary to use an aldehyde based disinfectant, potential health effects must be anticipated before work commences, and adequate protection, with particular emphasis on ventilation control, supplemented where appropriate by personal protective clothing and equipment, must be detailed in the relevant COSHH risk assessment, and must be employed at all times, to minimise exposure as far as is practicable. Health surveillance must be put in place if identified as being required as part of the COSHH assessment. Any instance of suspected sensitisation must be reported immediately using the University Health & Safety Report Forms and medical advice must be sought from the Occupational Health Adviser.

Autoclaving and disposal of waste from Containment Level 1 and 2 Facilities

Containment level 1(CL1) and 2 (CL2) facilities have access to an autoclave either within some laboratory suites or those in the central departmental autoclave facilities on F0.

If the waste is transported to the central autoclave facilities, robust, leak proof containers should be used.

Autoclaved waste from CL1 and CL2 facilities is routinely placed in black bins by the autoclave technicians and disposed of in the general waste bins as collected by the local authority.

Autoclaving waste from Containment Level 3 Facilities

Containment Level 3 (CL3) facilities must have an autoclave either within the laboratory or within the laboratory suite itself. Only authorised staff should undertake the decontamination of waste.

If the waste has to be removed from the CL 3 facility for autoclaving in an adjacent laboratory, it should be transported in a robust, leak proof container fitted with a lid. The lid of the container should only be removed when the container has been placed in the autoclave to allow steam penetration.

The autoclave must be available for immediate use once the waste arrives. This requires close co-ordination between the staff of the CL3 laboratory, and those in charge of the autoclaving facilities.

The container must be surface decontaminated with a suitable disinfectant before removal from the containment laboratory.

Autoclaved waste from CL3 laboratories must be disposed of in the Clinical Waste Bins (located in the Biology Stores compound area) for incineration.

Autoclave bag holders

Autoclave bag holders must be appropriate for the laboratory facility and type of material to be autoclaved. Laboratories handling pathogens must use either an autoclaveable bin or traditional autoclave bag stand (with or without foot operated lid). Standard plastic bins are only acceptable for work activities involving non-pathogenic organisms operating at Containment Level 1, and these should be periodically disinfected. To avoid unnecessary problems with contamination, plastic bins should be used without manually operated lids, unless required for containment of materials such as GM seed material.