Biological hazards or biohazards are organisms or products of those organisms that are harmful to human health and other living things. According to Safework Australia:
‘Biological hazards are organic substances that pose a threat to the health of humans and other living organisms. Biological hazards include pathogenic micro-organisms, viruses, toxins (from biological sources), spores, fungi and bio-active substances. Biological hazards can also be considered to include biological vectors or transmitters of disease’1
‘Exposure to biological hazards is therefore widespread and the risk of exposure is not always obvious’.1
Signage for Laboratories Using Microorganisms
Signs are used to inform personnel and visitors of potential hazards in the workplace.
The international biological hazard symbol is recognised worldwide as an indication of the presence of a biohazard. It is also used to identify rooms, equipment, containers etc., that either contain, or are contaminated with, a biological hazard.
The recommendation from the World Health Organisation (WHO) is that the international biohazard warning symbol be displayed prominently on doors to all laboratories and work areas where microorganisms of Risk Group 2 or higher are handled and/or stored.
The AS/NZS 2243.3:2010 Safety in Laboratories—Microbiological safety and containment states:
“5.2 REQUIREMENTS FOR PC1 LABORATORIES
A sign complying with Appendix D showing the level of containment, together with hazard symbols as appropriate and any access restrictions should be prominently displayed at the entrance.”2
The biological hazard symbol according to Appendix D is a black symbol on a yellow background. General microbiology laboratories should also have the laboratory containment level indicated on the sign in black letters as below.
School Science Laboratories
Generally, school science laboratories are classified as Physical Containment level 1 (PC1), if they conform to the requirements specified in Section 5 of AS/NZS 2243.3:2010 Safety in Laboratories—Microbiological safety and containment. If they conform to these requirements, then they are only suitable for work with microorganisms where the hazard levels are low, and where laboratory or facility personnel can be adequately protected by standard laboratory practice. This level of facility with its practices and equipment is usually suitable for secondary school teaching laboratories and undergraduate teaching laboratories.
Microorganisms that are classified as Risk Group 1, are the only ones that should be used in PC1 laboratories. Risk group 1 microorganisms are pathogens that present low individual and community risk—microorganisms that are unlikely to cause human, plant or animal disease. However, it should be understood that many of these microorganisms are capable of causing disease, given the appropriate circumstances. They are often referred to as opportunistic. People who are immunocompromised or immunosuppressed are more at risk. Higher levels of Physical Containment are required for handling microorganisms of Risk Groups 2–4.
Science ASSIST recommendations
Since microbiology activities are not conducted in every laboratory all year round, Science ASSIST recommends that a sign only be displayed at the entrance to the laboratory and/or preparation rooms whenever microbiological agents are being handled. The sign should be removed when biohazards are no longer present. This sign should include the biohazard symbol and laboratory containment level. Any access restrictions, plus contact information for responsible persons, should also be included.
A biohazard symbol should also be displayed on equipment such as incubators, fridges, freezers or containers when microorganisms are being stored. Again, this can be removed when the biohazard material has been removed.
There is no requirement to provide biohazard signage for food handling areas in the school environment.
As recommended by the World Health Organisation (WHO), Australian Standards have classified infectious microorganisms into four groups according to the degree of risk to humans, animals, plants and the environment. This classification system takes into account:
- the pathogenicity of the agent;
- the mode of transmission and the host range of the agent;
- the availability of effective preventative measures; and
- the availability of effective treatment.
Physical containment is the term used to describe facilities and procedures designed to reduce or prevent the release of viable organisms into the outside environment. In Australia, laboratories are classified into four levels of Physical Containment (PC 1–4). The level of containment must be of at least the level appropriate for the risk group of the microorganisms being used in the laboratory. That is, PC1 for RG1; PC2 for RG2 etc.
Chemical waste management
Regarding the disposal of hazardous waste, in general, it would not be acceptable to place organic solvents and heavy metal liquid mixtures in a fume hood to evaporate the majority of liquid and dispose of the remaining sludge via landfill. The recommended procedure is to safely store the chemical waste in appropriately labelled chemically compatible bottles for collection by a licenced waste disposal contractor.
Disposal of organic solvents
It is best practice to store waste organic solvents in separate containers as either Halogenated Organic Waste or Non-halogenated Organic Waste for collection by a licensed waste contractor. Halogenated organic wastes are those which contain chlorine, bromine or iodine; in schools, the most commonly encountered halogenated organic waste would be dichloromethane, or products of bromination reactions, such as dibromocyclohexane. Non-halogenated organic waste includes solvents such as cyclohexane, hexane, heptane, ethyl acetate, alkenes and alcohols. Mixtures of halogenated and non-halogenated waste should be treated as halogenated waste.
While it is not prohibited in Australia to evaporate volatile waste in a fume cupboard, it is not considered best practice, as this introduces untreated waste into the atmosphere (this method of waste disposal is prohibited in the USA). However, a local risk assessment may find that it is safer to evaporate these solvents if your school generates small amounts and if your waste pickups are few and far between.
It is best practice to not dispose of organic solvents down the drain. It is prohibited to dispose of a mixture containing a layer of solvent which floats on the surface of the water (i.e. is water-immiscible).
Some water authorities will accept solutions containing very small amounts of flammable solvents, such as ethanol or acetone, which are miscible with water. Check with your local water authority for their trade waste acceptance limits.
Disposal of heavy metal waste
Solutions of heavy metal waste should not be poured down the drain. It is best to collect different heavy metal waste solutions in separate waste bottles. If you have a waste solution that only contains the one type of metal ion, it is best to treat or store this separately; i.e., don’t generate mixtures of different types of waste unnecessarily.
Evaporation of the water from a solution of a mixture of heavy metals in an operating fume cupboard is an acceptable procedure. The sludge produced should be placed in a labelled bottle and stored for collection by a licenced waste contractor.
Other considerations when collecting and storing chemical waste for disposal
- Record on the bottle the substances which are added. The list of contents must be updated whenever a new type of waste is added.
- Chemical waste should be segregated in accordance with chemical compatibility and Dangerous Goods class whilst waiting for collection.
- It is important to keep chemical waste to a minimum. The use of micro-techniques should be considered if practical.
- Waste management could be incorporated in the learning activity to demonstrate the chemical principles.
Information and contacts for local waste water regulators can be found in our question on organic chemistry.
Science ASSIST is developing detailed information on handling chemical waste, which will be available in the coming months.
1 Safe Work Australia. 2011. ‘National Hazard Exposure Worker Surveillance: Exposure to Biological Hazards and the Provision of Controls against Biological Hazards in Australian Workplaces’, Safe Work Australia website http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documen...
2 Australian Standards AS NZS 2243.3-2010. Safety in Laboratories – Microbiological safety and containment. Reproduced with permission from SAI Global Ltd under Licence 1407-c117
Centers for Disease Control and Prevention. 2009. Biosafety in microbiological and biomedical laboratories (BMBL) 5th Edition. Atlanta, USA. https://www.cdc.gov/biosafety/publications/bmbl5/
Kindler, Lee. n.d. Signs and safety, Safe-T1 website, http://www.safe-t1.net.au/assets/files/resource/Safety&signs.pdf (Accessed 1 February 2016)
‘Microbiology’, University of Sydney website,http://sydney.edu.au/whs/guidelines/biosafety/microbiol.shtml (Accessed October 2015)
‘Warning sign – Biohazard authorised Personnel only’, Brady Australia website, http://www.bradyid.com.au/en-au/warning-sign-biohazard-authorised-personnel-only/fam-BRAU_PF835083.html?cat=BA01_010103 (Accessed 1 February 2016)
World Health Organization. 2004. Laboratory biosafety manual. Third edition. World Health Organization. Geneva. http://www.who.int/csr/resources/publications/biosafety/Biosafety7.pdf