Science ASSIST recommends a risk assessment be conducted prior to the use of all biological materials, and all appropriate control measures be identified and implemented. Science ASSIST has developed a one-page risk assessment template, see Risk Assessment Template. Where the risks are too high, elimination of the activity or substitution of a safer activity is recommended.
Science ASSIST considers this a high-risk activity and advises against its implementation in school science laboratories. The requirements of appropriate facilities and biosafety training and experience in order to deal with anything dead or decaying, puts this activity beyond the scope of most, if not all, schools.
Instead, we suggest that you consider an alternative activity to demonstrate the decomposition process. One idea is to suggest that the students perform a risk assessment on the proposed activity to identify the hazards, evaluate the risks and determine ways to eliminate or control the risks.
The following is a link to a University of Western Australia web page that contains information and alternative activities for teachers and students on Forensic Entomology using pictures, dichotomous keys and board games: http://www.clt.uwa.edu.au/asistm/forensic/entomology
We are also including some additional background information and useful links to the decomposition process at the end of the information below.
- The primary hazards of concern in fresh raw poultry meat are salmonella and campylobacter spp. They are both the cause of many cases of food poisoning even in low numbers 1, 2. See http://www.foodstandards.gov.au/publications/documents/complete_safefood... In particular chapter 3 pages 37–41, section on potentially hazardous food.
- Salmonella species, campylobacter species and many soil microorganisms such as clostridium and some bacillus species are classified as Risk Group 2.
- By incubating the raw chicken in the sun for 30 minutes, followed by burial in the ground, you are providing good conditions for the growth of microorganisms whose presence, concentration and pathogenicity is unknown. These microorganisms can include: those that occur naturally, but in low numbers, on the fresh raw material; bacteria; and other pathogens involved in the decomposing process as well as microorganisms from the soil, all of which can cause infection and disease.
- Burial also provides an anaerobic environment (i.e., without air), which encourages the growth of some very hazardous bacteria. In addition, there is a risk that the buried carcass may be dug up by local wildlife.
- Whilst there are some maggots that live underground, there is no guarantee regarding this. It has been suggested to leave the carcass on the surface, but the unpleasant odour from the decomposing carcass would be overwhelming and may also attract animals such as rats or local wildlife. Students generally do not cope well with the smell of appropriately sourced biological materials for dissections.
- It is recommended that microbiological material for use by students in school laboratories should not be taken from unknown origins or uncontrolled environments, which are likely to pose a health risk. All biological materials should be treated as if contaminated and potentially hazardous to health, and with standard precautions.
- For further information see https://education.qld.gov.au/curriculum/school-curriculum/CARA/activity-guidelines/biological-activities We also suggest reading the infection control guidelines developed by Sydney University: INFECTION CONTROL PROCEDURES - University of Sydney
- Infectious microorganisms could be released in the form of aerosols when manipulating the decomposed carcass while extracting larvae from the decomposing carcass for examination in the laboratory. This would need to be done using strict aseptic techniques in a controlled environment and appropriate PPE, such as safety glasses, latex/nitrile gloves, laboratory coat, closed-in shoes and potentially a mask, to avoid any contact with microorganisms involved in the decaying process.
- School science laboratories are generally 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. Some science laboratories may not even fit this criteria. If they do 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. Microorganisms that are classified as Risk Group 1 are the only ones that should be used in PC1 laboratories.
- Higher levels of physical containment are required for handling fresh human tissues or body fluids and microorganisms of Risk Groups 2–43.
- Schools would require a classification of PC2 to safely handle microorganisms from Risk Group 2 and therefore do not have the correct facilities to deal with the microorganisms that could be present in this activity.
- The National Hazard Exposure Worker Surveillance: Exposure to Biological Hazards and the Provision of Controls against Biological Hazards in Australian Workplaces report states:
- “The levels of training in the safe handling of biological hazards need improvement, particularly where workers are exposed to animals or animal products.” 4 p3
- “Poor understanding of biological hazards leads to poor risk assessments in workplaces.” 4p21
- Staff should have specific training in biohazards and possess suitable microbiological knowledge and training to deal with the potential hazards associated with anything dead or decaying.
Background information on forensic entomology
Forensic entomology is the study of the presence and life cycles of insects that colonise a decomposing body to estimate the time of death, often aiding criminal investigations.
Decomposition of a body begins with the action of microorganisms such as bacteria and fungi followed by the action of a series of insects. Decomposition is affected by the following factors.
- The environmental conditions such as temperature, exposure to sunlight, humidity and oxygen levels.
- Where the specimen is located (e.g. in water, enclosed space, buried, soil type and vegetation in the area).
- The state of the body (e.g. size, weight, cause of death, if burnt, if clothed).
- The presence of scavengers and insects, in particular, flies.
Weather conditions will affect how slowly or quickly a body decomposes. In general, the warmer the temperature, the faster the rate of decomposition. Temperature is also the most important factor affecting the rate of insect development.
The following links provide good information on various aspects of the decomposition process:
Australia New Zealand Food Authority. 2001. Safe Food Australia A guide to the Food Safety Standards. 2nd Edition. Canberra, ACT. http://www.foodstandards.gov.au/publications/documents/complete_safefood.pdf
Queensland Department of Education, Training and Employment. Biological Activities. https://education.qld.gov.au/curriculum/school-curriculum/CARA/activity-guidelines/biological-activities (Link updated September 2019)
Forbes, Shari Professor. School of Chemistry and Forensic Science, University of Technology, Sydney, New South Wales. Personal communication. March 2015.
Lewis, Simon Professor of Forensic and Analytical Chemistry, Director of Teaching and Learning, Department of Chemistry, Faculty of Science and Engineering, Curtin University, Perth, Western Australia. Personal communication. March 2015.
Safe Work Australia. 2011. National Hazard Exposure Worker Surveillance: Exposure to Biological Hazards and the Provision of Controls against Biological Hazards in Australian Workplaces.
Standards Australia. 2010. AS NZS 2243.3-2010. Safety in Laboratories – Microbiological safety and containment
Wallman, James Associate Professor Faculty of Science, Medicine and Health and School of Biological Sciences, University of Wollongong, New South Wales. Personal communication. March 2015.
1 Australia New Zealand Food Authority. 2001. Safe Food Australia A guide to the Food Safety Standards. 2nd Edition. Canberra, ACT. http://foodsafety.ood.telligence.net.au/food-poisoning-bacteria-and-viru... (last accessed 29 June 2016).
2 Australian Government Department of Health, Food poisoning and contamination Department of Health website, http://www.health.gov.au/internet/publications/publishing.nsf/Content/oh... (November 2010)
3 Australian Standards AS NZS 2243.3-2010. Safety in Laboratories – Microbiological safety and containment
4 Safe Work Australia National Hazard Exposure Worker Surveillance: Exposure to Biological Hazards and the Provision of Controls against Biological Hazards in Australian Workplaces. March 2011 http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documen... CC BY NC 3.0 AU