We use different information sources to help us decide which substances to include in an ATDS:
- Current Australian and international scientific and regulatory activities.
- Information from state and territory food regulators, expert authorities and advisory groups.
- Follow-up testing from previous studies to track changes in dietary exposure to chemicals over time.
Other factors that help us decide what to look at include:
A typical ATDS involves sampling about 100 different food types. Each ATDS has a different food list reflecting current dietary patterns and those that are likely to contain the chemicals being analysed. Consumption data from the
National Nutrition Survey helps guide what foods we choose to look at for each ATDS.
Food samples are collected in capital cities and selected regional areas in all Australian states and territories. They are purchased from a range of retail outlets including supermarkets, grocers, butchers, poultry shops, seafood markets, cafes and takeaways. Our aim is to capture the foods that reflect the normal purchasing habits of the population.
Foods are purchased over two sampling periods (i.e. winter and summer) to account for any seasonal variation in the food supply.
Foods are classified as either regional or national foods. Regional foods are more likely to be produced and sourced locally such as milk, tap water, fresh meat, fruit and vegetables, and may show regional variation in chemical concentrations. National foods (e.g. shelf-stable packaged foods (pasta, rice, cereal) and processed meats) are distributed nationwide and less likely to show regional variation in chemical concentrations. In general, higher numbers of regional food samples are collected.
We use specialist laboratory services to transport, prepare and analyse food samples.
Before they are analysed, food samples are prepared to a ready-to-eat state - the same way they would be at home. For example:
- washing (fruits and vegetables)
- removing inedible portions (banana peels, meat and fish bones, seeds)
- cooking (raw meat, vegetables, rice, pasta)
- adding hot water (tea, coffee)
- draining (canned vegetables)
After food has been prepared, the primary samples (individual food purchases) are combined into composite samples for analysis. Each composite sample is made up of three primary samples from a single state or territory.
Composite sample
A composite sample of apples from New South Wales contains 3 individual apple purchases from different parts of the state.
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For each food type included in the ATDS, multiple samples are collected and analysed for food chemical concentrations (typical range is 4 – 16 analysed samples per food type).
Dietary Exposure Assessment
Based on the results from the laboratory, we do a dietary exposure assessment using dietary modelling to estimate exposure of different Australian population groups to these chemicals through food and any risk they might pose.
Dietary exposure assessments are an important part of the ATDS. They translate the chemical concentration data for individual foods into dietary exposure estimates. These estimates help us decide if the amount of chemicals in food is safe, or if we need to investigate further.
We use food consumption data obtained from the most recent
national nutrition survey (2011-13 NNPAS) to inform our dietary exposure assessments.
Dietary Exposure = food chemical concentration x food consumption amount
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Find out more about
dietary exposure assessments.
Food mapping
We can’t test all foods consumed by the Australian population, so we use mapping to capture the total diet in our estimates of dietary exposure. Mapping is the process of matching the foods analysed in the ATDS to the foods consumed in the NNPAS.
Mapping:
Green apples and red apples, peeled or unpeeled, would be grouped into the raw commodity code for apples; or cheddar cheese, mozzarella cheese and all other types of ripened cheeses can be grouped in the single code for cheese and cheese products. |
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Population groups assessed
Dietary exposures is usually estimated for the Australian population as whole. Based on the currently available food consumption data, this is for Australians 2 years and above. If our dietary exposure assessment identifies a concern for a particular population sub-group, (i.e. children, infants or women of child bearing age), these groups may be assessed separately in the dietary exposure assessment to make sure the food is safe for these groups.
Risk characterisation
We look at information about the exposure to chemicals through food to determine what the risk is to Australian consumers. For the ATDS, this usually involves comparing estimated dietary exposure estimates to
HBGVs or other relevant health-based levels.
What we do with results
If we identify concerns, we follow this up with actions such as:
- Targeted surveys or investigations
- Standards development work (i.e.
proposals
- Consultation with relevant government authorities and industry
- Development of advice and other communication materials
The ATDS also gives us useful insights into trends in chemicals in food and dietary exposure over time. Findings can also be compared to overseas studies to provide an international context.
ATDS data is incorporated into Australia’s reference nutrient database, the
Australian Food Composition Database , and other
international databases which are used to inform international food safety risk analysis and our standards setting work.
The ATDS does not replace the need for targeted surveillance activities. It only provides a general indication of the levels of various chemicals across a broad range of foods in the general food supply. We use it to make estimates of Australian consumers’ dietary exposure - it does not investigate individual food products or regional areas and cannot be directly used for:
- Compliance and enforcement activity
- Regional investigations (such as local contamination concerns)
- Determining the distribution of substances in the food supply, a requirement for establishing regulatory limits such as maximum levels (MLs)
