Monday, May 7, 2012

Biohazard Management in Laboratory

Standard laboratories biosafety measures: The guidance and recommendations given as minimum requirements pertaining to laboratories of all biosafety levels are directed at micro-organisms in risk levels 1–4. Although some of the precautions may appear to be unnecessary for some organisms in risk group 1, they are desirable for training purposes to promote good (i.e. safe) microbiological techniques (GMT) Standard laboratory design and facilities In designing a laboratory and assigning certain types of work to it, special attention should be paid to conditions that are known to pose safety problems. These include: 1. formation of aerosols, 2. work with large volumes and/or high concentrations of micro-organisms, 3. overcrowding and too much equipment, 4. infestation with rodents and arthropods, 5. unauthorized entrance and 6. workflow: use of specific samples and reagents For proper design, wide space must be provided for the safe conduct of laboratory work for cleaning and maintenance. Walls, ceilings and floors should be smooth, easy to clean, impermeable to liquids and resistant to the chemicals and disinfectants normally used in the laboratory. Floors should be slip-resistant. Bench tops should be impervious to water and resistant to disinfectants, acids, alkalis, organic solvents and moderate heat Laboratory illumination should be adequate for all activities. Undesirable reflections and glare should be avoided. Laboratory furniture should be sturdy. Open spaces between and under benches, cabinets and equipment should be accessible for cleaning. While storage space must be adequate to hold supplies for immediate use and thus prevent clutter on bench tops and in aisles. Additional long-term storage space, conveniently located outside the laboratory working areas, should also be provided. Facilities for eating and drinking and for rest should be provided outside the laboratory working areas. Hand-washing basins, with running water if possible, should be provided in each laboratory room, preferably near the exit door. Safety systems should cover fire, electrical emergencies, emergency shower, eyewash facilities and first-aid areas or rooms suitably equipped and readily accessible should be available ). In the planning of new facilities, consideration should be given to the provision of mechanical ventilation systems that provide an inward flow of air without recirculation. If there is no mechanical ventilation, windows should be able to be opened and should be fitted with arthropod-proof screens. In BSL-2, an autoclave or other means of decontamination should be available in appropriate proximity to the laboratory (). In BSL-3, the laboratory must be separated from the areas that are open to unrestricted traffic flow within the building. Additional separation may be achieved by placing the laboratory at the blind end of a corridor, or constructing a partition and door or access through an anteroom (e.g. a double-door entry), describing a specific area designed to maintain the pressure differential between the laboratory and its adjacent space. The anteroom should have facilities for separating clean and dirty clothing and a shower may also be necessary (). Anteroom doors in BSL-3 may be self-closing and interlocking so that only one door is open at a time. A break-through panel may be provided for emergency exit use. Surfaces of walls, floors and ceilings should be water-resistant and easy to clean. Openings through these surfaces (e.g. for service pipes) should be sealed to facilitate decontamination of the room(s) (In BSL-3, the laboratory room must be sealable for decontamination. Air-ducting systems must be constructed to permit gaseous decontamination. Windows must be closed, sealed and break-resistant. There must be a controlled ventilation system that maintains a directional airflow into the laboratory room. A visual monitoring device with or without alarm(s) should be installed so that staff can at all times ensure that proper directional airflow into the laboratory room is maintained (). The building ventilation system must be so constructed that air from the containment laboratory BSL-3 is not recirculated to other areas within the building. Air may be high-efficiency particulate air (HEPA) filtered, reconditioned and recirculated within that laboratory. When exhaust air from the laboratory (other than from biological safety cabinets) is discharged to the outside of the building, it must be dispersed away from occupied buildings and air intakes. Depending on the agents in use, this air may be discharged through HEPA filters. A heating ventilation and air-conditioning (HVAC) control system may be installed to prevent sustained positive pressurization of the laboratory. Consideration should be given to the installation of audible or clearly visible alarms to notify personnel of HVAC system failure (). In BSL-4, the features of a containment laboratory BSL-3 are also applied to a maximum containment laboratory BSL-4 with the addition to class III cabinet laboratory. Passage through a minimum of two doors prior to entering the rooms containing the Class III biological safety cabinet(s) (cabinet room) is required (). Standard Code of practice: This code is a listing of the most essential laboratory practices and procedures that are basic to GMT. In many laboratories and national laboratory programmes, this code may be used to develop written practices and procedures for safe laboratory operations (). Laboratory personnel protection can be fulfilled by coveralls, gowns or uniforms must be worn at all times for work in the laboratory. Appropriate gloves must be worn for all procedures that may involve direct or accidental contact with blood, body fluids and other potentially infectious materials or infected animals. After use, gloves should be removed and hands must then be washed). For proper safety, personnel must wash their hands after handling infectious materials and before they leave the laboratory working areas. Safety glasses, face shields (visors) or other protective devices must be worn when it is necessary to protect the eyes and face from splashes, impacting objects and sources of artificial ultraviolet radiation (). For GMT, pipetting by mouth must be strictly forbidden. Materials must not be placed in the mouth. All technical procedures should be performed in a way that minimizes the formation of aerosols and droplets. The use of hypodermic needles and syringes should be limited. They must not be used as substitutes for pipetting devices or for any purpose other than parenteral injection or aspiration of fluids from laboratory animals (Also, all spills, accidents and overt or potential exposures to infectious materials must be reported to the laboratory supervisor. A written record of such accidents and incidents should be maintained. A written procedure for the clean-up of all spills must be developed and followed. Contaminated liquids must be decontaminated (chemically or physically) before discharge to the sanitary sewer. An effluent treatment system may be required, depending on the risk assessment for the agent(s) being handled (). The laboratory working areas should be kept neat, clean and free of materials that are not pertinent to the work. Work surfaces must be decontaminated after any spill of potentially dangerous material and at the end of the working day. All contaminated materials, specimens and cultures must be decontaminated before disposal or cleaning for reuse. Packing and transportation must follow applicable national and/or international regulations. When windows can be opened, they should be fitted with arthropod-proof screens ( In BSL-3, the code of practice for basic laboratories BSL-1 and 2 is applied with modifications as follows; laboratory protective clothing must be of the type with solid-front or wrap-around gowns, scrub suits, coveralls, head covering and, where appropriate, shoe covers or dedicated shoes. Laboratory protective clothing must not be worn outside the laboratory and it must be decontaminated before it is laundered. The removal of street clothing and change into dedicated laboratory clothing may be warranted when working with certain agents (e.g. zoonotic agents). Also in BSL-3, open manipulations of all potentially infectious material must be conducted within a biological safety cabinet or other primary containment device. Respiratory protective equipment may be necessary for some laboratory procedures or working with animals infected with certain pathogens. Because of the great complexity of the work in the BSL-4 laboratory, a separate detailed work manual should be developed and tested in training exercises. In addition, an emergency programme must be devised. In the preparation of this programme, active cooperation with national and local health authorities should be established). Essential biosafety equipment: Equipment should be selected to take account of certain general principles, i.e. it should be designed to prevent or limit contact between the operator and the infectious material. Also, it should be constructed of materials that are impermeable to liquids, resistant to corrosion and meet structural requirements and fabricated to be free of burrs, sharp edges and unguarded moving parts. Essential biosafety equipment include pipetting aids to avoid mouth pipetting. Also, biological safety cabinets should be used whenever infectious materials are subjected to centrifugation, grinding, vigorous shaking or mixing, sonic disruption and opening of containers of infectious materials whose internal pressure may be different from the ambient pressure. Plastic disposable transfer loops also should be available. Alternatively, electric transfer loop incinerators may be used inside the biological safety cabinet to reduce aerosol production. Screw-capped tubes and bottles, autoclaves or other appropriate means to decontaminate infectious materials are also required (

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