ENVH7001
Assignment 1 – QMRA: Problem Identification and Exposure Assessment report
Due date: 25th Mar 5pm, online submission on Turnitin via Blackboard.

Assignment
Recently, a lettuce farm in Brisbane was exposed to flash flooding caused by ex-Tropical
Cyclone Alfred. Although the floodwaters receded within two days, there is concern that
some of the lettuce may have been contaminated by the floodwater. Despite this
uncertainty, the farmers proceeded to harvest the lettuce once it reached maturity. The
harvested lettuce was washed and cleaned using rainwater collected on the farm to
remove dirt and debris. It was then packaged and prepared for transport to retailers.
Historically, flood-contaminated and uncooked lettuce have been associated with a high
risk of transmitting various diseases. To ensure food safety, the State Government food
handling authorities have required the farmers to conduct a first-tier QMRA, covering no
fewer than three pathogens, to evaluate the biological risks and determine whether
additional control measures are necessary to prevent disease.
The farmers have engaged your services to help establish the first two steps of the QMRA
framework, problem identification and exposure assessment, for presentation at a
meeting with the licensing authorities. Your task is to assess the exposure risk for an
average adult consuming fresh lettuce salad harvested from the farm.
Prepare a report addressing the following:
1. Problem Identification – Clearly define the potential hazards, including the
pathogens of concern and the possible routes of contamination.
2. Exposure Assessment – Estimate the potential exposure level of an average adult
to the identified pathogens through the consumption of the lettuce.
Ensure that your report follows a structured format and includes evidence-based
reasoning to support your analysis.

Report structure
Maximum 6 pages, excluding references, following the structure below:
1. Executive summary (max. 1 page, within page limit)
Short summary of the report, including objectives, summary of problem
identification and exposure assessment approach and major conclusions.

2. Introduction (max. 1/2 page, within page limit)
• Brief description of the scenario and introduction to the objectives of the
report.

3. Problem Identification (approx. 1 page, within page limit)
Formulate hazard identification including, but not limited to, the points below:
3.1. Define the scope and purpose of the study
• Define the problem’s boundaries from source to exposure
• Describe the lettuce production process using a block diagram.
3.2. Hazard identification
• Identify the pathogens, and/or indicative pathogens, and relevant information
including optimal conditions of survival, etc
• Describe the hazardous event
3.3. Exposure pathway
• Identify the exposure pathway
• Time frame between source and exposure (compare with pathogen survival)
• Potential growth that can happen between the source and the point of
exposure and implications in product packaging and transport conditions.
3.4. Health outcomes
• Identification of health concern (illness), duration, incubation time, etc.
• Any relevant costs and/or legislation considerations
3.5. Identify the risk management decision that has to be made

4. Exposure assessment (approx. 2 page, within page limit)
4.1. Source: report on relevant information and data to calculate the exposure
concentration C
• Identify possible source(s) of contamination.
• Pathogen exposure: Find ranges of values in literature from similar reports to
obtain occurrence data for the pathogen(s) and/or reference pathogen(s)
identified.
• Compare the pathogen values in this scenario with values found in literature
for similar cases (lettuce or other vegetables for raw consumption).
4.2. Intake: report on relevant information and data to calculate the ingested
quantity q per unit of time
• Define the frequency (single event, recurrent event – frequency) and unit of
exposure (amount ingested or inhaled, contact extension, number of vectors,
etc)
• Note 1: Not all of the listed elements in the items above are applicable to this
case study (e.g. lettuce tends to be ingested, not inhaled) – choose the
elements relevant to the pathogens that you identify relevant in the references
used).
• Note 2: You must search and obtain information and data for your risk
assessment using publicly available resources. Since this is a hypothetical
situation (as often is the case when trying to prevent risk before accidents
happen), you have to find typical ranges from literature and use them in your
calculation. Beware that all data must be supported by adequate
referencing, otherwise that section will not be considered valid.
• Note 3: Clearly state all assumptions made
• Note 4: in this assignment we only focus on these two first steps of the QMRA
framework. Identification of the dose-response profiles and subsequent risk
analysis and management actions will be covered in the next assignments.

5. Results (approx. 1/2 page, within page limit)
• Quantification of the magnitude and frequency of exposure (i.e. exposure
dose) for each of the pathogens identified in the steps above, taking into
account the considerations of the scenario and assumptions made.
• Clearly state all the steps used for these calculations.

6. Discussion and conclusions (approx. 1 page, within page limit)
• Critically analyse and discuss the situation and the results.
• Include a qualitative discussion about the reliability of the data sources and
implication of the results.
• Compare the results obtained with other values found in literature for lettuce
or other vegetables intended for raw consumption.
• Discuss the adequacy of the processing steps used in the lettuce production
process. Include also any other potential points of contamination identified in
your report.

7. References (no limit)
Use UQ recommended referencing style:
https://guides.library.uq.edu.au/referencing

8. Formatting
• Use one of the following fonts: Calibri 11pt, Times New Roman 12pt, Arial 11pt.
• Make sure all tables and figures have a caption. Captions should appear above
Tables and below Figures.
• All values used in the report must be adequately referenced (see point 7)

Suggested initial reading list
UQ Steps for writing assignments：https://my.uq.edu.au/information-and-
services/student-support/study-skills/assignment-writing/steps-writing-
assignments?p=0#0
UQ Academic Writing Skills, Chapter 17-21:
https://uq.pressbooks.pub/academicwritingskills/
Guide to Writing an Essay: https://www.scribbr.com/category/academic-essay/
Microbial Risk Assessment in food: Achievements and Future Challenges
https://www.fda.gov/media/78197/download
Australian and NZ food standards code:
https://www.foodstandards.gov.au/sites/default/files/2025-
03/Food%20Standards%20Code%20-%20Compilation%20%28March%202025%29.pd
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Marking scheme
Element Marks Excellent (80-
100%)
Good (60-80%) Average (40-60%) Poor <40%
Executive
summary
10 Effectively
summarises all
elements in the
report
Achieves goal
but poor clarity
Miss parts but
otherwise good
summary
Not a
summary
Introduction 5 Good
introduction,
and clearly
describes the
scenario and
objectives
Some faults in
key points for
problem
definition but
otherwise good
goal description
Report goal not
clearly stated or
serious faults in
problem definition
Does not
communicate
intent of report
Problem
identification
20 Excellent hazard
identification
and problem
definition.
Good hazard
identification but
some aspects
missing in
problem
definition.
Hazard
identification
incomplete and
many aspects
missing in problem
definition.
Very
incomplete or
incorrect
hazard
identification
and problem
definition.
Exposure
assessment
25 Exposure
assessment
approach
comprehensive
and correct
Exposure
assessment
approach misses
some of the key
aspects but
generally good.
Exposure
assessment
approach is
seriously
incomplete or
wrong.
Exposure
assessment
approach is
inadequate
Results 15 Calculations are
correct and
results are clear.
Some minor
errors in the
calculations or
slightly unclear
description of
the results.
Information
missing or goal not
addressed.
Major
information
missing or
clearly
erroneous
results.
Discussion &
conclusions
20 Result clearly
translated to
outcome
according to goal
and critically
discussed. Goal
missed or
bypassed.
Model goal not
completely
addressed or
critically
analysed.
Minor conclusions
presented as
major. Short in
critical analysis.
No critical
analysis
Presentation
overall.
5 Report is clearly
laid out and
within page limit.
Well integrated.
References
correctly
presented.
Correct format
used.
Minor
inconsistence
but well laid out.
Few mistakes in
references.
Slightly over the
page limit. Some
format
incorrections
Inconsistent
sectioning used.
Report does not
flow well. Many
referencing errors.
Over the page limit.
Several format
incorrection.
Difficult to
follow and
interpret. No or
inadequate
references.
Highly over the
page limit.
Many format
incorrection.


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