Safety in the Laboratory

Safety in the Laboratory

 

The practice of medical laboratory science is associated with hazards and accidents. The laboratory worker is very much at risk of acquiring transmissible diseases through contact with patients or handling of clinical specimens. Though accidents do occur in the best of laboratories, a poorly designed and overcrowded laboratory has the increased possibility of hazards and accidents. It should be noted however, that bad laboratory practices are the major causes of laboratory accidents. It follows, therefore, that the laboratory should be manned by well-trained, dedicated and meticulous staff. Every laboratory must have an appropriate code of safe laboratory practice. It is important that all accidents be promptly reported to the safety officer or to the officer in-charge of the laboratory

HAZARDS IN THE LABORATORY

The hazards and accidents in the laboratory may be discussed under the following areas:

1. Infection

2. Burns

3. Cuts and pricks

4. Hazards of toxic chemicals 
5. Electric shocks

1. Infection -Infections in the laboratory can occur in different ways, but the commonest causes are:

1. Inhalation of pathogens in air-borne droplets (aerosols) which are released during breakage or spilling of infectious fluids, centrifuging, dispensing or pipetting of infectious materials; and snap-opening and closing of specimen containers.

2. Ingestion of pathogens from contaminated food or fingers.

3. Ingestion of pathogens by mouth-pipetting. 

4. Pathogens finding their way into the body through needle pricks, cuts, scratches, insect-bites, sores or skin lesions.

2. Burns :- Burns sustained in the laboratory may be caused by:

1. Inflammable substances catching fire

2. Fires from bunsen burners, spirit lamps or from faulty or overloaded electric circuits

 3. Swallowing of corrosive substances during pipetting or spilling, such substances on the skin.

3. Cuts and Pricks- Cuts and pricks may result from:

1. Edges of broken glasswares.

2. Edge of a knife.

3. Accidental pricking with needle or any other sharp instrument

 4. Walking on glass chippings.

4. Hazards of Toxic Chemicals:-Hazards due to toxic chemicals result from:

1. Inhalation of fumes of toxic chemicals.

2. Swallowing or ingesting toxic chemicals during mouth pipetting.

3. Skin contact with toxic chemicals.

5. Electric shocks:-

Electric shocks, usually due to ignorance or carelessness can be caused by:

1. Faulty electrical circuits.

2. Incorrect installation of equipment.

3. Touching exposed live wires.

SAFETY PRECAUTIONS AGAINST INFECTION

All specimens arriving in the laboratory should be regarded as being potentially pathogenic. It is a very wrong notion to think that only specimens meant for bacteriological investigation are infectious. 

A specimen of cerebro-spinal fluid sent for glucose estimation may be a part of the same specimen sent for bacterial meningitis investigation. The same is true of a specimen of blood sent for hemoglobin or packed cell volume measurement which may contain infectious microorganisms.

The laboratory worker, must therefore, observe some "dos" and "don'ts" in order to prevent laboratory acquired infections. Some of the rules for the laboratory worker are : 

1. He/she should wear protective clothing (laboratory coats/gowns) over normal

clothing: preferably, wear closed shoes and not walk barefooted in the laboratory.

2. All specimens and infected materials should be handled with care.

3. He/she should avoid eating, drinking or chewing gum in the laboratory.

4. He/she should refrain from smoking in the working zone of the laboratory and also refrain from applying cosmetics in the laboratory

5. Nothing should be pipette with the mouth. Gummed labels should not be licked neither, should pens or pencils be put in the mouth, or stuck in the hair.

6. Protective gloves or plastic aprons should be worn when collecting blood sample for hepatitis, AIDS or viral hemorrhagic fever investigations.

7. Used needle should be inserted back into its guard immediately after use. But due to the increased awareness of the risks of infection from needle pricks, it is no longer advisable to recap used needles. Instead, "Sharp safe" containers should be made available for immediate disposal of used needles. The containers are finally incinerated.

8. When handling specimens or culture containing highly infectious pathogens gloves should be worn.

9. Process specimens or cultures containing highly  infectious pathogens in the safety cabinet.

10. Any cuts, insect bites, open sore or wounds should be covered with water-proof adhesive dressing.

11. Finger nails should be kept short.

12. All infected or contaminated materials should be disinfected before disposal.

13. There should be a jar of disinfectant on each bench at the start of the day's work. The disinfectant must be changed everyday.

14. In case of any spillage, disinfectant solution should be poured to cover the spilled material and left for

15 minutes before cleaning up.

15. Infected glassware should be disinfected by soaking overnight in hypochlorite solution and cleaning thoroughly under running tap water. At the end of the day, all the work benches should be cleaned with disinfectant.

17. Before leaving the laboratory for any length of time hands should be washed with soap and water thoroughly.

MAJOR CAUSES OF LABORATORY HAZARDS

The prevention of common accidents is very well documented in many laboratory manuals. It is very necessary that all members of the laboratory staff are conversant with the nature of these hazards and their prevention. The most common accidents even in the smallest laboratories are mainly due to the following:

1. Dangerous chemicals

2. Fire

3. Careless use of laboratory equipment,

Dangerous chemicals and reagents. 

1. Dangerous Chemicals  
 

Dangerous chemicals are used in the laboratories either directly or incorporated into reagents and stains. These dangerous chemicals include the highly flammable ones like ether or alcohols, highly corrosive ones like phenol or sulphuric acid, toxic ones like formaldehyde solution, carcinogenic ones like benzidine or explosive ones like picric acid

To minimise accidents caused by the chemicals, it is mandatory for manufacturers to label dangerous chemicals with hazard symbols and supply simple instructions for use and storage. 

It is also important to label clearly those reagents prepared from the dangerous chemicals. The labelling should include the nature and strength of the reagents or solutions, date of preparation, expiry date and any other safety warning applicable. It is advisable that only chemicals required for daily use should be kept in the main laboratory, and the others in the store room. It is also recommended to examine the containers periodically to detect in time any possible build up of pressure which may cause the container to burst.

The accepted hazard symbols are shown in Fig. 2.1.

Store rooms in which bulk stocks of chemicals are kept should be designed to reduce the risk of fire. Fire extinguishers should be placed just outside the store rooms.

They should also be well ventilated and adequately lit. Radioactive substances require proper supervision of their storage as provided for by the law.

The prevention of hazards and accidents due to dangerous chemicals and reagents lies mainly in the careful observance of safety precautions during handling and storage.

Flammable chemicals These chemicals should be stored in fire-proof metal boxes at ground level preferably in an outside, cool, locked store. 
Only small amounts of flammable chemicals should be left inside the laboratory. 

A container of flammable liquid should never be opened near an open flame. A bottle of ether should be opened at least three metres away from naked flame. "No smoking" rule must be enforced in the laboratory at all times.

Corrosive substances Corrosive chemicals such as strong acids (e.g., concentrated sulphuric or nitric acid) and caustic alkalis (e.g., sodium hydroxide, potassium hydroxide) should be stored at the floor level. Never mouth pipette a corrosive liquid; always use an automatic pipetter or dispenser. 

Eyes must be protected from the fumes of corrosive substances. When mixing, acid should always be added slowly to water, but never the reverse. In case of spillage, wear protective footwear when cleaning up the area. Wash acid and alkali burns under a free stream of running cold water. Toxic and irritating chemicals 

Toxic chemicals are equally irritating and can cause death or serious ill-health if swallowed, inhaled or allowed to come in contact with the skin. Some of these chemicals cause irritation of the skin and mucous membranes. Highly toxic chemicals such as potassium cyanide should be kept in locked cupboards. Wear protective gloves when handling a toxic substance
.

Always wash hands immediately after using a toxic or harmful chemical. Chemicals such as formaldehyde or ammonia with an irritating or harmful vapour should be used in a fume cupboard or safety cabinet. Always use an automatic pipetter or dispenser to measure a toxic chemical. 

Carcinogenic chemicals These chemicals are capable of causing cancer when inhaled, or ingested or when they come in contact with the skin. 

The chance of being affected depends on the length and frequency of exposure to, and concentration of the chemical. The carcinogenic substance should be stored in a closed container. Wear protective gloves and a face mask when handling a carcinogen. Wash everything used in handling the carcinogen thoroughly in cold water. 

Explosive chemicals An explosive chemical can explode as a result of heat, flame or friction. Chemicals such as picric acid should be stored under water. Never leave such an explosive chemical in a dry state. Radioactive chemicals All areas where radioactive materials are stored or used must be posted with caution signs. 

Traffic in this area should be restricted to essential personnel only. Decontamination of laboratory equipment, glassware and work areas should be routinely done on a regular basis. 

Note

Only properly trained personnel are allowed to work with radioactive chemicals; such persons must be regularly monitored to ensure that the maximally possible dose of radiation is not exceeded.

REPORTING ACCIDENTS

Any accident in the laboratory involving personal injuries, even minor ones, should be immediately reported to the person in-charge of the laboratory. This first report of injury should be followed by an accident investigation report. 

The injury report should contain the name of the injured person, time and place of injury, and nature of injury. The investigation report should include the information on the injured person, an account of the accident, the cause of the accident, the nature of the injury and the actions to be taken to prevent a recurrence.

Most accidents occur due to two main causes: 

1. Environmental factors These include unsafe conditions such as inadequate safeguards, use of improper or defective equipment, hazards associated with the location or poor housekeeping. 

2. Personal factors Personal factors are improper laboratory attire, lack of skills or knowl edge, specific physical or mental condition and at titude to work

Safety Equipment

Safety equipment has been developed specifically for use in the clinical laboratory. Equipment for accident prevention and control includes fire extinguishers, fire blankets, first-aid supplies, safety showers, eye-wash stations, spill kits and hazard labeling systems.

For personal protection, safety glasses or protective work shields should be used to protect the eyes and face from splash and impact. Gloves and rubberised sleeves or gowns protect the hands, arms or body. Closed footwear should be used.

BIOSAFETY IN CLINICAL LABORATORY

Bio safety involves safe handling and disposal of hazardous biological materials in the laboratory. These materials consist of infectious agents themselves as well as substances actually or potentially contaminated with them. 

A large number of laboratory workers handle such materials as part of their daily routine. These workers should be aware of the risks of infection while handling the specimens, and must know appropriate laboratory practices to avoid these risks.

In 1984, the Centre for disease Control (CDC) and the National Institute of Health (NIH) issued guidelines for use in working with infectious agents in the laboratory. It has been recommended that all specimens from all patients should be considered potentially infectious.

The approach is referred to as "universal precautions" and eliminates the need to identify the patients infected with human immunodeficiency virus (HIV) or other blood borne pathogens. 

Infectious agents such as HIV have been isolated from blood, semen, saliva, urine, cerebrospinal fluid, tears, breast milk, cervical secretions and tissues of infected persons. 

A laboratory worker should consider skin (especially when scratches, cuts, abrasions or other lesions are present) and mucous membranes of the eye, nose, mouth and respiratory tract as potential pathways for entry of infectious agents.

Needles and other sharp instruments must be carefully handled and properly discarded. Spilling and splashing of infected materials should be avoided.

Summary of "Universal Precautions for Laboratories" by CDC

1. Universal precautions should apply to blood and all body fluids containing visible blood, semen, vaginal secretions, tissues, cerebrospinal fluid, pleural fluid, peritoneal fluid, pericardial fluid, synovial fluid and amniotic fluid.

2. Laboratory workers should use protective barriers appropriate for the laboratory procedure and the type and extent of exposure expected. All persons processing blood should wear gloves and laboratory coats; and these should be removed before leaving the laboratory. Biological safety barriers should be used wherever necessary.

3. Hands should be washed immediately when contaminated with blood or other body fluids, after removing gloves, and after completing laboratory activities.

4. Use of needles and syringes should be minimised. They should be used in situations in which there is no alternative. If used, needles should not be recapped, or bent or broken by hand. After use, needles and other sharp instruments should be placed in a 'sharp-safe' puncture-resistant container for disposal.

5. Specimens of blood should be placed in strong, leak-proof containers during transport.

6. Mouth pipetting must not be performed in the laboratory. Mechanical pipetting devices should be used.

7. Contaminated materials used in the laboratory should be decontaminated appropriately before reprocessing or disposal.

8. Laboratory work surfaces should be cleaned and decontaminated with appropriate disinfectant after a blood or body fluid spill and at the end of day's work.

Specific Precautions against Hepatitis B Virus (HBV) and Human Immunodeficiency Virus (HIV) Infections

An accidental injury such as needle-stick injury to the worker with infectious material from a known case of HBV or HIV infection should be immediately followed by the following.

For HBV infection HB vaccine and HB immunoglobulin, test for HBV antibody. 

For HIV infection Treatment with zidovudine (AZT), test for HIV antibody.

After that a follow up at 1.5, 3 and 6 months.

Containment

Contamination with infectious material is the greatest hazard in clinical microbiology laboratories. Clinical laboratory personnel, including cleaners, clerical staff and maintenance personnel, and also any visitor who enters the laboratory, are subject to the risk of laboratory infection. For this reason, there is growing concern about safe practices, procedures and facilities in the laboratories. Adherence to the principles of biosafety contributes to a healthier and safer work environment for the laboratory staff and the surrounding community
.

The term containment essentially describes safe methods for managing infectious agents in the laboratory environment where they are being handled or maintained. The purpose of containment is to reduce exposure of laboratory workers and other persons to, and to prevent escape into the outside environment of potentially hazardous agents. 

The three elements of containment include:

1. Laboratory practice and technique 
2. Safety equipment (Primary barriers)

3. Facility design (Secondary barriers) 

1. Laboratory practice and technique Each laboratory should adopt or develop a biosafety manual which specifies practices and procedures designed to minimise or eliminate risks. Persons working with infected materials or infectious agents must adhere to standard microbiological practices and techniques required for safe handling of such materials. They should be aware of the potential hazards of improperly packed, broken or leaking packages, and of the proper methods for their handling and decontamination. The use of vaccines may provide an increased level of personal protection. 

2. Safety equipment (Primary barriers) Safety equipment includes biological safety cabinets and use of enclosed containers designed to prevent formation of aerosols. There are three types of biological safety cabinets used in microbiology laboratory (Class I, II, and III). These are described in Microbiology Section of this book. Safety equipment also includes items used for personal protection such as gloves, coats, gowns, face shields and safety glasses, and should be used wherever appropriate.

3. Facility design (Secondary barriers) The design of the laboratory facility depends on the laboratory's function and the risk of transmission of the infectious agents being manipulated. The basic facility design may include separation of laboratory work area from public access, availability of decontamination facility such as autoclave, and handwashing facilities. As the risk of transmission of more hazardous agents increases, special design features such as specialised ventilation systems, airlocks at laboratory entrances, or separate buildings or modules for specialised work area may be provided.

Biosafety Levels 

There are four biosafety levels (BSL) to which in fectious agents are assigned on the basis of their virulence. Each biosafety level has guidelines for appropriate containment level which consist of combinations of laboratory practices and techniques, safety equipment and laboratory equipment. Table 2.1 details the biosafety levels for infectious agents recommended by the CDC. Biosafety level

1 Biosafety level 1 is for laboratories in which work is done with well-defined and characterized organisms not known to cause disease in healthy adult humans. It includes certain non-virulent strains of Escherichia coli (such as K-12) and Bacillus subtilis. This BSL involves standard microbiological practices and safety equipment is not needed.

Biosafety level 

2 Biosafety level 2 is the minimum level for clinical laboratories in which work is done with moderate risk agents present in the community and associated with human disease of varying severity. Hepatitis B virus, Salmonella species and Toxoplasma species are some examples of microorganisms assigned to this containment level. BSL 2 includes good microbiological practice, limited access to the work area, decontamination of all infectious wastes, use of protective gloves, and a biological safety cabinet of Class I or II for use in procedures that may create aerosols. In other circumstances, these agents can be used safely in activities conducted on open bench
.

Biosafety level 3 Biosafety level 3 is necessary in the laboratories in which work is done with agents that are associated with risk of serious or fatal aerosol infection. Mycobacterium tuberculosis, Brucella species, Yersinia pestis. Coccidioides immitis, and a wide variety of viruses including human immunodeficiency virus (HIV) are included in BSL 3. At this containment level, more emphasis is placed on primary and secondary barriers to protect personnel, community and environment from exposure to potentially infectious aerosols. Properly maintained biological safety cabinets (Class II and III) should be used for all manipulations of infectious materials.

Biosafety level 4 Biosafety level 4 practices, safety equipment and facilities as indicated in Table 2.1 are applicable to work with dangerous and exotic agents which pose a high risk of life threatening disease to individuals. Maximum containment and decontamination procedures are used in containment level 4, which is usually found only in reference and research laboratories. Only a few viruses such as Lassa, Ebola and Marburg are classified in BSL 4.

BIOSAFETY PROGRAMME

Responsibility for Safety

Both the employer and the employee share the responsibility for safety in a clinical laboratory. The employer has moral and legal obligations to provide a safe workplace. The employee also should be aware of his role in his own safety and the safety of his co-workers. There should be a laboratory safety programme with clearly stated responsibilities of the management and the employees.

Responsibilities of the Management

1. Development of a safety programme to establish laboratory work methods and safety policies.

2. Establishment of a safe workplace, including the provision of proper safety equipment and personal protective equipment where needed.

3. Establishment of appropriate on-the-job training for the employees so that they are aware of proper safety practices, and provision of supervision and guidance to laboratory workers whenever necessary.

4. Development and implementation of an effective infection control programme.

Responsibilities of the Employee

1. Knowledge and compliance with the established laboratory work practices.

2. Conduct of safe work practices and utilisation of personal protective equipment.

Most accidents occur due to two main causes: 

1. Environmental factors These include unsafe conditions such as inadequate safeguards, use of improper or defective equipment, hazards associated with the location or poor housekeeping. 

2. Personal factors Personal factors are improper laboratory attire, lack of skills or knowl edge, specific physical or mental condition and at titude to work

Safety Equipment

Safety equipment has been developed specifically for use in the clinical laboratory. Equipment for accident prevention and control includes fire extinguishers, fire blankets, first-aid supplies, safety showers, eye-wash stations, spill kits and hazard labelling systems.

For personal protection, safety glasses or protective work shields should be used to protect the eyes and face from splash and impact. Gloves and rubberised sleeves or gowns protect the hands, arms or body. Closed footwear should be used.

3. Proper notification of unsafe conditions to the immediate supervisor.

4. Positive attitude towards training, facilities, co-workers and supervisors.

DISPOSAL OF MEDICAL WASTE

Health care facilities such as hospitals and clinical laboratories generate large amount of waste material that can prove harmful to the community at large if proper precautions are not taken for its disposal. This waste is collectively called "medical waste". Medical waste is defined as special waste from health care facilities that may transmit infectious diseases. It comprises articles and products such as

1. Blood and blood products

2. Microbiological waste

3. Pathological waste

4. Sharp instruments such as syringe needles 

5. Disposable equipment such as syringes,tongue depressors, intravenous bags. It is important to identify potentially infectious waste so that it can be separated from the main waste stream and disposed off in a safe way.

1. Handling of Medical Waste

Proper handling of medical waste involves the assurance that it is placed in designated containers and decontaminated in time using proper technology. General guidelines are:

1. All medical waste should be placed in a leakproof container which is puncture resistant and rigid enough to avoid leakage or puncture during transportation. The containers should be clearly labelled with biohazard symbol.

2. All sharp instruments such as needles, blades and glass objects should be placed in special puncture resistant (sharpsafe) containers before placing them in the disposal bag. Needles should not be transported, recapped, bent or broken by hand.

3. Waste should only be handled by those who have been trained in proper handling.

4. All the medical waste must be disposed off by one of the recommended procedures.

5. If contaminated waste needs to be stored for any length of time before disposal, it should be placed in a secured area accessible only to those who are responsible for its disposal.

 Methods of waste disposal The approved methods for disposal of medical waste include:

1. Incineration.

 2. Steam sterilisation followed by removal to landfill.

3. Inactivation by heat.

4. Chemical inactivation or oxidation.

 5. Encapsulation in a solid matrix.

2. Fire

Fire can break out in any laboratory if proper safety precautions are not observed. It is essential that the laboratory staff is properly educated on the causes and controls of fires. The fire can be caused by: 

(a) Ordinary combustibles such as paper, wood, etc.

(b) Flammable liquids such as ether, alcohols, etc.

(c) Gases such as methane

(d) Metals such as magnesium, potassium, etc.

(e) Faulty electric circuits or appliances

Precautionary measures against fire

1. The laboratory staff should have fire drills from time to time.

2. Fire extinguishers for all types of fire must be kept handy in the laboratory. The fire extinguishers in common use are water, foam, dry powder, carbon dioxide and halogen. (The use of halogen may be discontinued due to its adverse effect on the atmospheric ozone layer.)

3. Fire extinguishers should always be free and in good working condition.

4. Keep flammable liquids away from naked flame.

5. In case of a major fire, someone should be delegated to take charge of fighting the fire. The practice of regular fire drills will help minimize casualties.

3. Equipment or Instrument-related Accidents

Accidents occur as a result of incorrect positioning, installation and wrong use of equipment. Poor maintenance and irregular servicing of equipments also lead to accidents.

It is important to position the equipment in such a way that safety and convenience afe given priority over other considerations. It is therefore essential not to overcrowd the bench with too many equipments. Equipment like refrigerators and freezers should not be placed too close to the wall.