Research laboratories contain many caustic and corrosive substances as well as toxic, flammable, and unstable reagents. All containers of hazardous chemicals must be clearly labelled. Laboratory management has the responsibility to inform employees of significant chemcial hazards. Laboratory personnel have responsibilities to themselves and to their co-workers to learn of these hazards and to follow safe practices.
Hazardous chemicals can be grouped into the following categories:
Corrosive as a reagent label should refer to any substance that causes visible destruction or irreversible alterations in human tissues at the site of contact. When applied to chemical waste, the term implies a pH less than 2.1 0r more than 12.5, or the ability to corrode steel (SAE 1020) more than 0.250 inches/yr at 130o F.
Toxic is the term that can be applied to almost any substance in quantity. For laboratory purposes, a substance is considered toxic if serious biologic effects follow inhalation, ingestion, or skin contact with relatively small amounts. Toxic effects of chemicals may be subdivided as follows:
a) irritants (either local or systemic)
c) those which have reproductive effects
Flammable and combustible liquids are subdivided by their flashpoints. See the label or the Material Safety Data Sheet.
Explosive chemicals are those reactive and unstable substances which readily undergo violent chemical change. Explosive decomposition may occur at normal temperatures and pressures.
1.3 Storage of corrosives
Store corrosives near to the floor to minimize danger of falling. Plastic carriers must be used for containers of concentrated reagents over 500ml.
Care must be taken not to store mutually incompatible chemicals in the same area. For example, organic acids such as acetic acid or acetic anhydride should be stored separately from strong oxidisers such as sulphuric, nitric or perchloric acids.
1.4 Storage and handling of flammable liquids
Refer to 'Fire Prevention and Control'.
1.5.1 Handling of carcinogens
Where possible, every effort must be made to use non-carcinogenic (or less toxic) chemicals in preference to carcinogenic (or highly toxic) substances. When using carcinogens, the ALARA principle, As Low As Reasonably Achievable, should be adopted. Exposure to carcinogenic or other highly toxic chemicals can occur by:
- inhalation of dust or vapour
- absorption through the skin from contaminated clothing, spillage on benches, floors or from apparatus
- ingestion from contaminated hands or food, or smoking.
The following work practices should be followed:
- No food, drink or tobacco shall be taken into, prepared or consumed where carcinogenic or highly toxic chemicals are used or stored
- Hands must be washed immediately upon completing a procedure where a chemical carcinogen has been used and when leaving the work area. Immediately after skin contact or emergency exposure to a carcinogen, wash or, if appropriate, shower the affected area
- Pipetting by mouth is strictly forbidden. Mechanical pipetting aids or disposable pipetting tips should be used
- Do not attempt to recap or cut used needles. Dispose the entire needle and syringe in a sharps container for disposal as hazardous waste
- Warning signs should be located on the door of the work area where carcinogens are used (e.g. Caution - Limited access. Carcinogenic chemicals in use)
- Carcinogenic chemicals should be dispensed from the location at which they are stored. The amount taken should be no more than is required immediately and the aliquots should be labelled with a carcinogen warning and the name of the substance
- Face mask, gloves and lab coat must be worn when weighing toxic or carcinogenic chemicals. The area must be free of air draughts and any spills must be appropriately cleaned up
- Working surfaces should be covered with an absorbent material backed with plastic (Benchkote is found on level 6 in the kitchen area) and should be replaced at regular intervals or when a spillage occurs
- All experiments involving dust, vapour or aerosols of a carcinogenic nature should be carried out in a high efficiency fume cupboard. Laminar flow cabinets do not protect the worker from exposure to the carcinogen and should not be used for this purpose
- Regular housekeeping of bench areas should be performed to prevent contamination from spreading to other areas within the workplace. Special clean-up procedures for spilled carcinogens are described further in the document and should be considered prior to using a chemical.
1.5.2 Storage and Labeling
Designated areas (e.g. an entire laboratory, an area of a laboratory, or a device such as a fume-cupboard) should be identified where carcinogens are used or are to be used. Doors into areas where carcinogenic chemicals are used should be marked to identify the nature of the hazard (e.g. Caution - Limited access. Carcinogenic chemicals in use).
All carcinogenic, suspected carcinogenic or highly toxic chemicals should be stored in screw-cap containers or ampoules at the appropriate temperature and labeled clearly, indicating the chemical composition, date of preparation and the nature of the hazard (ie. Carcinogen - Handle with care). Their solutions or suspensions must be stored safely, and labeled indelibly using efficient self-adhesive stickers. Carcinogens should be packaged to withstand shocks, pressure changes, and any other conditions that may cause leakage of contents.
These materials should be stored in designated areas, cabinets, or refrigerators within the primary work or storage area, with consideration given to incompatibilities with other substances. The MSDS provides information on incompatibilities of classes of chemicals. Precautions should be taken to protect from rodents, weather, incompatible chemicals, and spillage. Additional storage requirements (e.g. use of double containers) may be necessary for certain highly potent carcinogens with physical properties that enhance spontaneous release and exposure (e.g. highly dispersible powders or volatile solids).
If it is necessary to transport such chemicals within the laboratory, the sealed container should be placed in a second unbreakable container to minimise the risk of accidental breakage or spillage.
An inventory of chemicals should be maintained where they are stored in the workplace.
Before beginning a laboratory activity that involves a chemical carcinogen, plans should be developed for the handling and disposal of contaminated wastes and surplus carcinogens. Users should properly segregate, package and label all solid and liquid wastes contaminated with carcinogens. Under no circumstance should carcinogenic or highly toxic chemicals be disposed of down drains or into the atmosphere. Sodium azide is a particular hazard as it forms deposits in drains.
Disposal containers can be obtained from the Technical Officer on level 6.
When labeling the containers, details of the carcinogens which will be disposed of should be clearly identified. All containers that hold carcinogen waste should have a label that states the type of hazard e.g. carcinogenic waste - contains (name of carcinogen).
The following decontamination procedures should be followed to prevent spreading of carcinogens within the workplace (See also CarcinogenDecontamination.pdf):
- After using any carcinogenic or highly toxic chemical, users should always rinse their hands well in cold water then wash them thoroughly with soap and hot water.
- Contaminated glassware or equipment should be neutralised with chemicals or washed separately with solvents appropriate for the chemical. The glassware or equipment should then be rinsed in cold running water and washed and brushed in hot water and detergent before being assigned to any routine washing procedure.
- Contaminated benches should be wiped down with cold water followed by hot water and detergent. Similarly, all benches where a carcinogenic or highly toxic chemical has been used should be cleaned regularly, irrespective of known contamination.
- It is essential that an effective system is in operation for the cleaning of protective equipment and for the laundering of laboratory coats.
- Prior to maintenance work being conducted in the area or upon any piece of equipment, all work should cease and the area and equipment be decontaminated. Particular care should be taken to avoid contamination of drains and ventilation ducts.
- Cytotoxic drug cabinet decontamination and the removal and disposal of HEPA filters should be carried out only by specially trained personnel.
1.5.5 Ventilation requirements
Ventilation for controlling exposure to carcinogens may include a combination of the facility features and engineering controls listed below:
- Negative pressure of the workplace relative to common areas (e.g. corridors).
- Filters, traps and scrubbers on air, vacuum and ventilation piping.
- Chemical fume hoods, glove boxes, closed systems and other isolation devices.
- Non permeable work surfaces.
- Secondary containment trays.
Laboratory fume hoods (excluding laminar flow cabinets) are designed to provide protection for the user from chemical and radiological contaminants which are used inside the hood. Use of carcinogenic or highly toxic chemicals should occur in the fume cupboard, not on an open bench.
It should be noted that though fume cupboards are designed to protect the user from the hazardous substances being used, fume cupboards do not eliminate exposure 100% even under ideal conditions. Careless work practices can cause considerable exposure to a user who may believe they are protected. To optimise the performance of the fumehood, the following work practices should be adhered to:
- Ensure that the fume hood has a current inspection sticker (dated within the last year). If the face velocity of the fume-hood has failed the inspection, work involving carcinogens should not commence until the fume hood exhaust system is repaired.
- Utilise the hood with the sash positioned as low as possible (usually 45cm in height). This will ensure adequate face velocity and allow the sash to act as a protective shield. Keep hood sashes down to an opening of about 15cm when the hood is not in use to conserve energy in variable air volume systems.
- The fumehood is not a storage cabinet. Do not store significant quantities of chemicals within the hood as these materials can obstruct the air flow or exacerbate an incident or emergency in the hood. However, minor quantities of waste or highly toxic chemicals may be stored within the hood, as this may be safer than storing on the open bench. Highly hazardous chemicals should not be stored in fumehoods in which high hazard processes are being undertaken (e.g. heating, pressurised equipment etc).
- The degree to which these controls should be applied depends on the safety level of the operation. For example, use of solid materials may not require a ventilated enclosure, but highly volatile chemicals or those that generate aerosols or dusts should be conducted in a ventilated enclosure or with a local exhaust system above the process.
- Analytical instruments that produce vapours or aerosols should be connected to a mechanical exhaust system when used with carcinogens. 'Ductless' hoods should not be used for carcinogens.
- Glove boxes are used for handling highly toxic substances, unsealed radioactive materials and for carrying out operations with extremely high emission rates. Glove boxes are operated under negative pressure using a pump or exhaust fan arrangement. The exit gases should be trapped or filtered through a HEPA filter and then released into the hood exhaust.
- A cytotoxic drug cabinet is used where a sterile environment is required for the product being worked with, but personnel protection is also required. A typical example of when these cabinets are used is during the weighing out of cytotoxic drugs.
1.5.6 Personal Protective Equipment
A risk assessment of the process and a review of the material safety data sheet will indicate which control measures are required to control the worker's exposure. When controlling exposure to occupational hazards, the Workplace Health and Safety Act requires that the hierarchy of controls be followed (i.e. controls ranging from elimination and substitution of the hazard, to ventilation, through to personal protective equipment). Personal protective equipment is considered the least effective control measure and should only be considered to complement other control measures.
Personal protective equipment should be chosen for its suitability to the task (e.g. comfort, enables dexterity of movement) as well as to the chemical and physical properties of the substance to be used, its volatility, stability, flammability, solubility and miscibility. When working with hazardous chemicals, the minimum laboratory attire which must be worn is laboratory coat, safety glasses and closed footwear. Additional protective equipment such as face shields, gloves and respiratory protection (where ventilation is ineffective) may be required in certain cases.
When handling carcinogenic chemicals, chemically resistant gloves must be worn. A chemical resistance guide for glove materials should be used to determine the best type of glove for the carcinogen being handled. For example, Ansell-Edmont produces a chart which lists glove materials and the permeation and degradation ratings for use with particular chemicals. This chart, in conjunction with the material safety data sheet should be referenced prior to commencing work with carcinogenic chemicals. Gloves should be inspected before each use, cleaned and replaced periodically.
Protective equipment should be stored adjacent to the work area and should not be taken to other areas of the laboratory. Laboratory coats, in particular, should be removed and stored before leaving the laboratory and should not be worn in rooms designated for eating and drinking. Protective clothing (e.g. labcoats) should be cleaned by an industrial laundry rather than being taken home by the wearer.
1.6 Material Safety Data Sheets
Material safety data sheets (MSDS) are required for hazardous substances and dangerous goods. The manufacturer or importer of a substance must prepare the MSDS and provide it to the user (employer) on the occasion of the first supply of goods to the user. In addition, a manufacturer must prepare a new MSDS when significant new information becomes available on the substance.
In order to assist the supplier, chemical purchasers should include with their order a specific request for an MSDS when they do not already have an MSDS for the material. Material safety data sheets should be available to workers. In many cases a summary form of the MSDS is found preferable for general use, rather than the multiple paged and often complex full details. Within the University of Queensland MSDS information on most chemicals used within the University can be obtained through access to Chemwatch on the University network ( http://www.uq.edu.au/ohs/?page=141354).
1.6.1 Role of MSDS
The material safety data sheet has a number of roles for managing the safe use of chemicals.
- It should first be used to ensure that the product is being used as intended by the manufacturer or importer. Other use may be possible, but particular care should be taken when the product is being put to a 'new' use - it may give rise to unforeseen hazards.
- It is the key tool for risk assessment as it includes detailed hazard information.
- The options for appropriate controls included in the MSDS may be utilised for the design and improvement of control measures and procedures.
- Workplace monitoring and health surveillance strategies may often be based on advice contained in the MSDS.
- Sufficient information should be provided to select the necessary safety equipment and to develop necessary emergency procedures.
- The MSDS may be used as the basis of a training program for workers as it covers hazards, precautions and emergency procedures.
1.6.2 Information provided by an MSDS
A wide range of information is provided in an MSDS. It is the most comprehensive source of information available to a chemical user.
a) Identification information
- The name of the product is clearly specified together with classifications appropriate to the product - United Nations substance number, dangerous goods class and subsidiary risk, hazardous substance status, poisons schedule etc.
- The manufacturer's or importer's name, address and telephone number is provided, often with a 24 hour-a-day telephone contact for emergencies.
- The name (and CAS number) of hazardous ingredients is given together with their approximate proportion in the product composition.
b) Specific chemical properties
A wide range of specific chemical and physical properties are listed:
- Boiling point and vapour pressure, which give an indication of the potential to generate significant vapour concentrations. Low boiling point and high vapour pressure materials will generate higher vapour concentrations at ambient conditions.
- Vapour density (VD) - the ratio of the density of the vapour to that of air. This determines the behaviour of the gas or vapour in air. Substances with a VD < 1 will rise in air. Substances with VD >1 will tend to sink in air and flow along horizontal surfaces and down stairs drains etc. Ether fumes are particularly hazardous.
- Solubility of the substance in water and other solvents expressed in a variety of units (eg g/L) or descriptive terms (insoluble, dispersible, slight, partial, soluble, miscible).
- Specific gravity of a liquid - the ratio of the density of the substance compared to that of water. This enables a determination of whether the substance will float on or sink in water.
- The pH of the product gives an indication of acidity (if pH < 7) or alkalinity (if pH > 7).
- Fire safety data such as:
-flammability range, the range of concentrations of fuel in air between the lower flammability limit (LFL) and the upper flammability limit (UFL), over which a mixture of a material
-flash point (fp), the lowest temperature of a liquid at which the vapour above it can be ignited
-auto-ignition temperature (AIT), the lowest temperature (of a potential ignition source) at which a flammable mixture in air can be ignited.
- Other hazardous chemical reactivity - corrosivity, oxidising properties, reactivity with common substances (eg air and water) tendency to spontaneous combustion or self accelerating polymerisation, shock or light sensitivity.
c) Health hazard information
Information is included on the acute and chronic health effects of substances, the major routes of exposure (inhalation, ingestion, skin absorption, eye contact). The results of any animal toxicity testing is provided with particular emphasis on the potential for carcinogenicity or reproductive hazards. First aid instructions and advice for the medical practitioner are given.
d) Precautions for use
The relevant workplace exposure standards (TWA, STEL and ceiling if applicable) are supplied for use in the planning or workplace controls. Specific engineering controls such as ventilation, are set out. Personal protective equipment recommendations are given. In higher standard MSDS the face protection, respirator and glove recommendations are specific to the product. Specific recommendations are provided for the prevention of fire and explosion.
e) Safe handling information
Information is provided in MSDS on procedures for the safe storage and transport of the substance including any special requirements, codes or restrictions which apply. Recommendations are outlined for clean-up of spillage and disposal of waste. Fire fighting methods and associated protective equipment are specified.
f) Other information
A range of other information is included in the MSDS on environmental data, references and emergency contact points.
1.7 Organic solvents
The basis for classification of organic solvents is by chemical composition. The members of the same class, in general, have similar solvent characteristics and chemical action. However, important variations in toxic effect often occur within the group. These harmful effects may follow inhalation of the vapour, eye or skin contact with liquid or vapour, or by ingestion. Inhalation is usually the most significant route of entry into the human body, while some organic solvents may be absorbed through the skin with or without causing damage to the skin itself.
A general summary of toxic responses is presented for organic solvents in a subsequent section. However, it is important to stress that solvents produce their own individual biological responses, and as such each solvent should be evaluated prior to its use. Where there is a likelihood that workers will be exposed to organic solvents, steps should be taken to minimise the exposure. Any exposure must be below the Worksafe Australia workplace exposure standards. Control measures would include elimination, substitution for less toxic products, enclosure of work procedures and processes, local exhaust ventilation, appropriate work practices, and the use of personal protective equipment to prevent skin contact and inhalation. Careful consideration of each of the chemical components is required to determine the overall health hazard of these mixtures. In particular, products which contain n-hexane, benzene, trichloroethylene, methyl n-butyl ketone, diethyl ether, carbon tetrachloride, and carbon disulphide should be closely scrutinised. Efforts should be made, where practicable, to eliminate, substitute or minimise their concentration in the formulation to be used. If this is not possible further engineering controls such as enclosing the process or providing local exhaust ventilation, should be implemented.