Safety is the duty of all members of laboratory staff to co-operate in the prevention of the accidents. Those who don't take adequate precautions are a danger to themselves and possibly to others as well, maybe this danger could reach the community also.
In addition to the welfare of the laboratory staff there is concern for preservation of the building, equipment, furnishings and apparatus. Accidents are also a waste of time. It is the duty of the employing authority to provide safe working conditions in the form of adequately ventilated laboratories with suitable equipment such as benching with non-absorbent crack-free surfaces. Fume cabinets, protective clothing and the senators for hand washing. In addition to this, those in charge of the directories have legal obligations for safety, and a number of the regulations are in force such as radioactive substances and carcinogenic substances.
It is recommended a senior member of staff is appointed as safety officer and that he should have a responsibility for the accident book in which all accidents and their consequences are recorded after they occur. The safety officer should make certain that protective clothing such as masks and goggles are available, that all apparatus and equipment is tested regularly including safety equipment and fire-fighting apparatus. He should check that infective material and dangerous chemicals are disposed of safely, that the legislative requirements are complied with and that first aid supplies and notices about the action to be taken in the event of fires, accidents and emergencies are all available.
Infection
The hazards of working with live germs in a microbiology laboratory are well recognized. There is an obvious danger from direct contact with cultures of pathogenic organisms, but the greatest danger is from the breathing of aerosols produced by careless handling of infected materials. All materials sent to pathology laboratories are potentially infectious with the possible exception of tissues in formolsaline. Specimens sent for chemical or hematological examination are just as likely to contain pathogens as specimens to the microbiology laboratory. All new recruits to the laboratory must be warned that specimens received by the laboratory are likely to be infectious and that the outside of specimen containers may be contaminated by the contents even when visibly clean. The consequences of self-infection by careless handling of materials such as blood containing hepatitis virus must be pointed out. Infective droplets are probably the major source of laboratory infection and some droplets are formed whenever a fluid service is broken. The smaller droplets evaporate almost at once to form nuclei of dried airborne material which can travel some distance in the area and which, if inhaled may reach the alveoli of the lung. Aerosols may persist in the air for some time. Careful technique can reduce the droplet formation, but they are formed in many procedures, examples of which are given below:
- Pipetting or rinsing Pasteur pipettes.
- Centrifuge, especially if breakage occur.
- Decanting supernatant after centrifugation.
- Opening screw-top bottles such as universal containers.
- Opening snap-off caps or plug stopper of plastic containers.
- Homogenizing and grinding material for culture.
- Shaking culture.
- Ultrasonification of culture.
- Accidents such as when a tube containing culture gets dropped or knocked over.
- Heating wire inoculation loops in gas flame.
- Making films for example from sputum.
- Careless use of discard jars.
- Post-mortem examination of infected subjects.
As many of these procedures as possible should be done in an exhaustive cabinet and always if there is a likelihood of material being infected with particularly dangerous organisms such as tubercle bacillus. After accidents in which there has been an aerosol produced, it is recommended that the windows should be opened and that the room be evacuated for ten minutes before cleaning up and disinfection.
If the skin becomes contaminated it should be washed immediately and contaminated clothing should be removed and autoclaved or disinfected. If an accident involves the breakage of a glass vessel containing infectious material, the area must be folded with a phenolic disinfected at once. Broken glass is picked up using forceps and a pan and brush, but not handled directly. The disinfectant should be given between 30 and 60 minutes to act before the spillage is mopped up. All such accidents must be reported to senior member of staff.
Chemical hazards
Chemical may be poisonous, corrosive, carcinogenic, or explosive. Bottles and other containers should be carried with both hands underneath giving support. Larger bottles, particularly those containing dangerous chemicals should be transported in carriers. Corrosive chemicals such as acids and alkalis are stored on low shelves and opened with care. Mouth pipetting is always potentially dangerous and some form of safety pipettes must be used instead. Procedure involving boiling solvents, toxic gases and vapors must be carried out in an efficient fume cupboard. Dangerous chemicals obtained from commercial sources usually carry a warning printed on the label. These warning should be observed. Bottles containing poisons must be clearly labeled "poison" and stocks of substances must be locked away in separate cupboard and the key held by senior member of staff.
Equipment such as rubber gloves, goggles, rubber boots, a respirator, dust pan and brush, mop and sand should be available for dealing with spillage of noxious chemicals. The procedure to be adopted will depend upon the nature of the spilt chemicals and should be directed by a senior member of staff.
Carcinogens are chemicals capable of provoke uncontrolled neoplastic change in tissues, in simple terms cancer production. These chemicals should be avoided as far as possible in the laboratory, but if it is necessary to use them, then the operator should wear disposable gloves, like infection, exposure can occur from inhalation, through the skin, and by ingestion. The risk involved depends mainly upon the length and frequency of exposure and the concentration of the carcinogen, but it is possible for even quite small exposures to be potentially hazardous. The following are some of the carcinogenic chemicals used in laboratories, alpha and beta naphthylamine, benzidine. Orthotolodine. Orthodianisidine, the nitrosamines, the nitrosophenoles, the nitronaphthalenes and selenite.
Fire
Fire is one of the most serious and most likely hazards to occur in a laboratory. All laboratory staff should know where the fire extinguishers are and how to use them, the rules concerning the fire-alarm system and the location of the fire exits. The most generally useful fire extinguisher in the laboratory is the carbon dioxide cylinder can be safely used with most chemicals and electrical equipment and is clean. Dry powder extinguishers are also useful and may be more effective with some types of fire but are missy in use. Carbon tetrachloride, water and water based extinguishers such as soda-acid foam extinguisher can be dangerous in laboratories and should be avoided. Asbestos blankets are useful for smothering small fires and burning clothing. These should be placed near at hand in the laboratory for instant use. Only the absolute minimum of flammable solvents should be kept in the laboratory: bulk stocks should be outside in fire resistant cupboards according to the fire regulations. Serious laboratory fires have been started by ignition of flammable liquids by sparking contacts in electrical apparatus. Laboratories should be also kept clean, tidy and free of rubbish. This will help to prevent the outbreak or spread of fire.
Hazards from apparatus and equipment
It is possible to receive a fatal shock from as little as 60 volts under adverse conditions. Mains-operated apparatus must be safely constructed with correctly connected earthing points switches in the live wires. All electrical apparatus must be kept clean and dry and must be regularly serviced by a competent electrician. Faulty apparatus must be withdrawn from service. Many pieces of apparatus and equipment are dangerous if not operated correctly.
Exhaust protective cabinets
All laboratories handling potentially materials for example laboratories in hospitals with renal dialysis units should be equipped with exhaust protective cabinets. Care must be taken to choose a suitable cabinet which should have the following features. An air flow through the working opening of the cabinet of not less than 100 linear feet per minute (0.508 meters per second). The air should be drawn out of the cabinet through one or more bacterial filters and discharged into the open air. The exhausting fan should be at the point of discharge of the air that there is a negative pressure in the cabinet and trunking, and thus any leaks in the system will allow air to leak in rather than contaminated air to leak out of it. If the air from the cabinet is discharged in the vicinity of open window the then there should be high efficiency filter incorporated in the system. Cabinets are generally fitted with UV light, which should be switched on for an hour or so after use to aid the disinfection of the cabinet. Before the filters are changed or before maintenance the whole cabinet and trunking should be disinfected bi boiling 100 ml of formalin in the cabinet with the fan running and the working opining partly closed, to ensure that the air flow does not fall below 100 feet per minute such as may happen toward the end of the working life of the filter, some form of gauge or air-flow meter should be incorporated into the system. In cabinets which have a sloping glass panel at the front, care must be taken with the poisoning of gas burners in case the glass is cracked by the flame.
Disposal of specimens and culture
All infectious and potentially infectious materials must be rendered safe before disposal. Flasks, bottles, test tubes and other media containing vessels must be autoclaved before being sent for wash-up. Cultures, slides, swabs and many specimens can be autoclaved. Others can be incinerated. Plastic pertri dished and tubes must be autoclaved separately before disposal or incinerated in a specially designed incinerator. Fluids and urine samples are treated with an equal volume of hypochlorite or phenolic disinfectant. Pasteur pipettes, microscope slides and other items should be discarded into discard jars containing hypochlorite or phenolic disinfectant which should prepared fresh daily. Disposal syringe needles must be discarded into a rigid container immediately after use until they can be incinerated.
Personal care
Clean protective clothing must be worn at all times in the laboratory. This may include the wearing of protective clothing and wash hands after handling any infectious material. On leaving the laboratory, take off protective clothing and wash hands, for example, when going to tea, eating, drinking and smoking in the laboratory are forbidden. This is particularly important where there are infectious materials, corrosive reagents or flammable solvents. Habits like nail-biting, pencil-chewing. Sitting on benches and licking gummed labels must be strongly discouraged. All accidents including minor pricks, cuts and abrasions must be reported to the person in charge. Common sense is the key to safe working in a laboratory. Discard glass-ware with damaged edges use proper racks to hold test tubes and bottles
Protective immunization and screening of new laboratory personnel
The head of the department must ensure that all recruits to laboratory staff have a chest X-ray examination before employment which repeated annually or sooner if there is clinical suggestion of infection with tuberculosis. Screening for Australia antigen regular intervals should also be considered. Protective immunization should be offered to staff for the following infectious: tetanus, smallpox, diphtheria and typhoid. Before employment potential laboratory staff should have a tuberculin test such as Mantoux test and BCG (Bacillus Calmette-Guérin) inoculation must be given to those who are negatively reacting. They must not handling tuberculous material until the skin reaction becomes positive. In addition, when special organisms are studied such as anthrax, rubella or measles, suitable inoculation may need to be given. Laboratory staff should be vaccinated every three years and again should there be an outbreak of smallpox locally.
The work must be panned for safety as efficiency by using inherently safe technique, and sending off dangerous work such as sensitivity testing of tubercle bacilli and Treponema pallidum immobilization tests to a few well-equipped laboratories with experienced workers.
