by Roy Ellis
E-mail: roy.ellis@imvs.sa.gov.au
Web: http://www.adam.com.au/royellis
There will always be those who oppose rigid safety control in medical laboratories and there will always be those who support the need for sensible management of safety issues. Thankfully, the latter is becoming more commonplace as we identify and learn more about the many hazards staff face each day in a medical laboratory environment.
This article will not relate all of the legislative requirements of the Federal, States and Territory governments in their Occupational Health, Safety and Welfare Acts. It will attempt to reinforce the argument for stringent, sensible control of the use of personal protection, where required in a histology laboratory, as opposed to lax acceptance of nonconformance with its counter argument of ‘What do those bureaucrats know? I know what I am doing – I have done it this way for years’. Here is an attempt to motivate the complacent to comply with protective equipment recommendations and to provide ammunition for frustrated safety representative who daily attempt to gently coerce those who will forever bury their heads in the sand rather than face rational change.
What are the possible hazards faced by someone who works in a histology laboratory?
Sources of potential injury include:
If you cut, pour, mix, clean, centrifuge, heat, freeze or syphon anything during your daily routine you will generally need some form of personal protection unless you work in an ultra modern facility with every safety feature devised to aid the laboratory worker. Especially when the cutting is fresh or even fixed biological material; the mixing is toxic solvents and carcinogenic and/or teratogenic chemicals. The cleaning is bloody, contaminated surfaces, the centrifugation is of biological material. The heating is of paraffin wax with its oily aerosol that inhaled can cause granulomatous lesions in lungs. With further heating of chemical solutions in microwave ovens and antigen retrieval in pressure cookers. And the freezing is fresh biological tissue.
The possible hazards are many. The consequences of ignorance can be enormous and fatal for someone who fails to heed sound, sensible advice and ignore an offer of personal protection. Their lack of sensitivity could also have devastating effects on family and co-workers.
What needs to be protected when someone works in a histology laboratory?
At some stage there may be a need to protect the eyes, face, head, ears, feet, hands and arms or whole body, depending upon what task is being performed at a given time. But remember, where a hazard has been identified and does exist, investigating the possibility of changing something, a method or a chemical, to reduce or remove the hazard is far better than persisting with the hazard even if personal protective equipment is used to control the hazard.
What PPE should be provided to ensure adequate protection?
PPE includes laboratory gowns, goggles, safety glasses, face shields, gloves, safety shoes, respirators and earmuffs or plugs. If large quantities of solvents or hazardous solutions are handled a fully enclosed protective suit with breathing apparatus should be available in case of a large liquid spill where corrosive or toxic fumes are generated.
Gowns
WHY?
A gown should cover all of your outer garments protecting them from contamination. If your outer clothes reach your shoes then the gown should also. Elasticised wristbands stop cuffs from dangling into hazardous solutions. A tie at the back leaves the front with unbroken protection.
Gowns should be changed daily because during the course of a single day they can become heavily contaminated with a variety of agents depending upon exposure. Perhaps a spot of blood from fresh tissue upon which you are doing a frozen section. A spot of blood overflowing with tubercle bacilli from that fresh lymph node, which the surgeon forget to note on the request form. Or the fresh, or paraffinised, brain biopsy with Creutzfeldt Jakob that slipped through the security net, for Prions are not inactivated by formalin fixation and tissue processing. Later in the day you spill a carcinogenic dye powder that you are handling to make up a fresh, working solution or a passing breeze blows a puff of dust into your unprotected nostrils. Perhaps there is a splash from a toxic chemical as you do a cut-up- remember that it takes time, sometimes hours, for formalin to inactivate bacteria in fresh tissue. Perhaps a splash from an acid that is handled badly. Perhaps you wiped your contaminated, gloved hand down the side of your gown after coverslipping. And what if the hand that was not gloved was wiped down the gown, what contamination might be transferred to that hand? The list is long. Washing hands before donning a clean gown ensures that the gown is free from any contamination at the beginning of the day.
Many different types of infecting agents have been grown from uniforms worn by hospital staff. The heaviest contamination was found in accumulated debris in pockets of those uniforms and gowns that had pockets.1
Gowns should only be worn in the laboratory. They should be removed before leaving the laboratory. Whatever might contaminate the surface of the gown is then left behind. Never should a laboratory gown be worn in a staff dining area or an area where food or drink is prepared or eaten.
If the material is not impervious to penetration by contaminating agents your own clothing will also eventually become contaminated. Soft, absorbing, cotton scrubs as worn by operating theatre staff are not a suitable alternative to a heavy, cotton, fluid-resistant gown in a laboratory. Polyester gowns can be impermeable to fluids but also generate static electricity which can cause havoc when section cutting.
If a gown is not worn in the laboratory it is your own clothing that will bear the brunt of any contamination. Clothing that might suffer the effects of an acid burn, blood or fresh tissue contamination and traces of carcinogenic dust. Clothing that accompanies you when you eat, when you return home.
Would you be happy to pick up and cuddle your baby or your grandchild while wearing your laboratory gown?2 A gown that you might have worn for a week or two in a heavily contaminated setting. A gown that might be smeared with blood or other detritis. A gown with a few small acid burns and coloured by dye smeared along the surface from contaminated hands or gloves. I would hope that the answer would be no. Yet if you fail to wear adequate protection in the laboratory over your own clothes it is those clothes that will catch the drop of blood, the tiny bit of contaminated tissue, the splash of acid, the smear from dirty fingers. It is those clothes that you will wear home to cuddle the baby. Is the price of non-conformance too high? I would hope that the answer would be yes.
Eye protection
WHY?
The type of eye protection required depends upon the hazard. For most situations, safety glasses with side shield are adequate. Where there is a definite possibility of a biological or chemical splash occurring, such as during cut-up or when making up fresh reagents, goggles offer greater protection. Where solutions are mixed which have the potential for explosion, such as making up ammoniacal silver solutions, or when using strong caustics or acids or when removing chemical mixtures and dye solutions from a microwave oven after heating, a full, face shield should be worn. Once the cornea has been damaged or burned, there is an irreversible loss of sight.
If blood or tissue contamination occurs the eye protection should be durable enough to withstand disinfection in a dilute sodium hypochlorite solution (1-5%).
Contact lenses should not be permitted because:3
If, despite all precautions, an employee should experience a splash to the eye the eye needs to be flushed with cold water, using continuous soft flow of water for at least 15 to 30 minutes.4 Cold water should be used as warm water aids absorption of contaminating substances through the mucous membrane to beneath the surface of the eye. Soft flow enables the eye to be kept open without discomfort for the time needed to ensure adequate cleansing. For 15 to 30 minutes because some substances will begin to penetrate the mucous membrane and it will take 15 to 30 minutes to flush these substances to the surface.
Hand protection
WHY?
Exposure of an ungloved hand to potentially infective material can result in illness and possible death if the infecting agent penetrates the bodies defence mechanism. Bacterial, viral and prion contamination can occur from transport of these contaminants from hand to mouth or by absorption through skin.
Exposure of an ungloved hand to chemicals and solvents can result in serious burns, defatting of skin and/or dermatitis. 5 Skin can also become sensitised to a frequently handled chemical resulting in a worker who is no longer able to function in a laboratory anywhere near the chemical that has caused the sensitisation. Formalin, xylene and xylene substitutes cause sensitisation.5 Some chemicals, such as concentrated phenol, can be absorbed through skin in concentrations sufficient to cause horrific injuries and even death from respiratory failure.5
Factors, which can effect the properties of gloves, need to be considered when selecting gloves for a specific purpose.6 Properties, which need to be considered, are:
BUTYL rubber gloves protect against acids and peroxides and remain flexible at low temperatures.7
NATURAL LATEX are pliable and comfortable. Gloves will protect against most water solutions of acids, alkalis, salts and ketones as well as fresh human material. In some individuals latex causes an allergic reaction. Hypoallergenic gloves, glove liners and powderless gloves may be an alternative for these individuals.7
NEOPRENE gloves have good pliability and protect against alcohols, organic acids and alkalis.7
NITRILE gloves stand up to heavy use and provide protection against chlorinated substances.7
LEATHER gloves protect against extreme heat and extreme cold.7
DO NOT use gloves, which contain asbestos particles. Asbestos particles, when inhaled, are known to be one of the primary causes of malignant mesothelioma.
Gloves should not be worn outside of the laboratory.
Shoes
WHY?
The greatest danger to feet in a medical laboratory is from a spilled, corrosive or irritating chemical. Shoes with gaps or those with surfaces, which can be penetrated, do not provide adequate protection.3 Additionally, heavy-duty leather also offers protection against objects, which may be dropped on to feet such as microtome knives or full winchesters of liquid. If a corrosive or irritating chemical is spilled it is better to be wearing a shoe that can be removed quickly without the need for hand contact. Slip-resistant soles (rubber) will prevent slipping on wax impregnated surfaces.
Breathing apparatus
WHY?
The air that we breathe into our lungs should be free from substances, which will damage fragile tissues or cause toxicity. Where possible, room design and other controls, such as downdraft ventilation and/or fume hoods, should be used to minimise exposure to toxic and corrosive fumes. Where sufficient means for ensuring air quality are not incorporated into a laboratory design a respirator should be provided. A respirator should be comfortable to wear and be provided with filters suitable for the offending vapour. A simple, carbon filter facemask can be used where small amounts of vapour are present or where there is a non-toxic dust hazard.
In addition, for your own personal protection:
Visitors to the laboratory should follow the same PPE policy as employees. It is the laboratory’s responsibility to ensure the safety of visitors.
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