BY MUHAMMAD BELLO MUSTAPHA
Biosafety is the application of combinations of laboratory practice and procedures, laboratory facilities and safety equipments when working with potentially hazardous agents. The management of biological hazards through the proper application of engineered containment and administrative controls is referred to as biosafety or biohazard control. Bio-related research activity may involve manipulation of microbial, animal or plant cells. The risks associated with these activities arise from the sample and/or procedural requirements. Adherence to standard microbiological techniques and using facilities suitable to the risk level of the pathogen helps to protect the researcher from laboratory acquired infections. Biosafety practice is targeted at workers, co-workers, lab support personnel, general public, environment and products.
Hazards related to bioresearch can be classified in to two categories:
- Hazard related with the pathogen or human/animal cells being used in a research.
- Hazards related to the procedure and practices followed in the lab.
Researchers who handle or manipulate human or animal cells are at risk of possible exposure to potentially infectious pathogens that maybe present in those cells/tissues. The human cell lines may contain blood borne pathogens, which can be transmitted due to improper handling.
ROUTES OF ENTRY FOR PATHOGEN
The probable routes of entry are:
- Inhalation of infectious aerosols.
- Contact of the agent with the skin, eyes or mucous membrane.
- Inoculation by contaminated sharps.
- Bites from infected animals or contact with their body fluids.
- Ingestion of infectious agent through mouth pipetting or contaminated
Aerosols generated during research activities remain undetected and can spread easily and remain suspended in the laboratory atmosphere for a long time. They possess a serious hazard to the person performing the task and also to others who are exposed to the air from the laboratory. Aerosols can be generated during the following activities:
- use of sonicators and vortex mixers.
These respirable size particles when inhaled are retained in the lungs and can cause infection to the person.
The risk from the pathogen handled depends on the following factors:
- Capability to cause infection in the host and the severity of the same.
- Preventive measures and treatments available.
- Route of entry
- Infective dose level
- Stability in the environment
- The range of cells/strains that can act as a host.
The term containment is used to describe the safe work practices in handling infectious agents to reduce exposure to laboratory personnel and others.
TYPES OF CONTAINMENT
- Biological containment
- Physical containment
Biological containment: any combination of vector and host which is to provide biological containment must be chosen or constructed to limit the infectivity of vector to specific hosts and control the host-vector survival in the environment.
Physical containment: helps to confine the pathogenic organisms being handled and prevent exposure to personnel.
Primary containment equipments: this includes biological safety cabinets and enclosed containers (e.g. Safety centrifuge cup).
Secondary containment: proper design of the facility helps in protecting personnel inside the facility and also prevents the release of pathogenic organisms outside the facility.
Biosafety level is applicable to facilities in which work is done with indigenous or exotic agents where the potential for infection by aerosols is real and the disease may have serious or lethal consequences. Biosafety requires in addition the following requirements:
- special clothing
- directional airflow
- controlled access
- double door entry/anteroom
GOOD MICROBIOLOGICAL TECHNIQUES
- open flame must not be used because it can distort the air flow pattern and damage the filters.
- always use disposable gloves. Do not touch mouth, eyes and face with contaminated hands.
- food and drink must not be stored or consumed in the laboratory.
- glassware must be replaced with plastic ware wherever possible.
- sharps (e.g., needle sticks, glass) must be avoided wherever possible as it can transmit blood borne pathogens in case of injury.
- use engineered sharp-safety devices when syringes and needles are necessary.
- needles must not be recapped, to prevent needle stick injury.
- puncture-proof containers fitted with covers must be used for disposing sharps.
- tubes and specimen containers must always be securely capped (screw-capped if possible) for centrifugation.
- refer to manufacturer’s instructions before operating equipments.
- work area must be decontaminated with a suitable disinfectant at the end of the work.
- hands must be thoroughly washed before leaving the lab.
PERSONAL PROTECTIVE EQUIPMENT
- personal protective equipment must be selected on the basis of the risks involved in the task performed.
- lab coat, safety glasses and toe covered footwear is a minimum requirement while working in the lab.
- face shield must be used if there is any risk of splashing of infectious materials.
- gloves must be worn for all procedures that may involve direct contact with blood, infectious materials, or infected animals.
- gloves must be removed aseptically and autoclaved with other laboratory wastes before disposal.
- if re-usable gloves are used, on removal they must be cleaned and disinfected before re-use.
- lab coats and other personal protective equipment used must not be used outside the laboratory.
BIOSAFETY CABINETS: biological safety cabinets provide containment of infectious aerosols generated during the laboratory procedures. Biosafety cabinets offer protection to laboratory personnel and to the laboratory environment.
EMERGENCY MEASURES IN CASE OF EXPOSURE TO BIO SAMPLES
- remove the contaminated clothing.
- wash the skin thoroughly with soap and water.
- in case of eye contact flush the eyes with water.
- report the exposure to the lab in charge.
- get medical attention immediately.
- decontamination renders an item (work bench, equipment, etc.) Safe to handle by reducing the number of organisms to below the threshold infectious dose level such that transmission is unlikely to occur.
- decontamination requirements will depend on the experimental work and the nature of the infectious agent handled.
- decontamination is usually accomplished by steam sterilization or autoclaving.
- sterilization and disinfection are different forms of decontamination.
- sterilization makes an item free from all living microorganisms and viruses.
- the process of sterilization can be accomplished by applying heat.
- is not as effective as sterilization, as some organisms such as bacterial endospores may survive.
- a disinfectant is a chemical or mixture of chemicals used to kill microorganisms, but not spores. They are usually applied to inanimate surfaces or objects.
- sodium hypochlorite and formaldehyde are the disinfectants recommended for general laboratory use.
- for special purposes phenolics compounds, alcohols, iodine etc., can be used effectively.
BIOHAZARD WASTE DISPOSAL
Biohazard waste generated in laboratories must be segregated into the following:
- non-contaminated general waste.
- “sharps”-needles, glass pieces, etc
- contaminated material for autoclaving and recycling
- contaminated material for incineration
- biohazard waste for autoclaving must be collected in red plastic bags and those for incineration in yellow non chlorinated plastic bags.
- biohazard waste of human and animal origin must be incinerated.
Environmental health and safety agency: England (UK)
Spanish National Research Council (CSIC) : Department of Plant Food Science and Technology.
Muhammad Bello Mustapha Writes from Faculty of Science, Department of Science Laboratory Technology, Federal Polytechnic Bali, Taraba State.