Dietary exposure and intake assessments at FSANZ
Dietary exposure assessments are a major component in many Food Standards Australia New Zealand (FSANZ) projects.
What is a dietary exposure assessment?
A dietary exposure assessment is the process of estimating how much of a food chemical a population, or population sub group, consumes. Dietary exposure to (or intake of) food chemicals is estimated by combining food consumption data with food chemical concentration data. The process of doing this is called ‘dietary modelling’.
Dietary exposure = food chemical concentration x food consumption
At FSANZ we may compare the estimated dietary exposure to a food chemical with a known reference health standard to find the level of risk to the population.
What do the terms exposure, intake, consumption and food chemical mean?
Dietary exposure refers to exposure from food chemicals that are inadvertently present in food, or added to food for a technological purpose.
Dietary intake refers to the dietary ingestion of nutrients (including energy, water, macronutrients, sodium, minerals or vitamins), nutritive substances, novel foods or food ingredients, or biologically active substances, which have a nutrition or health purpose.
Food consumption refers to the consumption of foods or beverages by individuals or populations.
Food chemical refers to food additives, contaminants, agricultural and veterinary drug residues, novel ingredients, nutrients and other chemicals in food (e.g. caffeine). It does not include micro organisms.
What is risk analysis?
The scientific risk analysis of chemicals in food, which is what scientists do when developing national and international food standards, comprises three major components (see Figure 1):
- risk assessment
- risk management
- risk communication.
Figure 1 The Codex Alimentarius Commission Risk Analysis Framework
What is risk assessment?
Risk assessment is a four step, science-based approach that uses experimental and other available data to characterise the risk and arrive at a conclusion regarding the potential risk associated with a food or food ingredient. Dietary exposure assessment is one of these steps (see Figure 2).
Figure 2. The four steps in risk assessment
We use dietary exposure assessments to assess the potential risk to health from proposed changes to the food supply, or when monitoring the levels of food chemicals in the food supply. Such assessments are a crucial third step in the risk assessment process. They may also be useful in identifying risk management options and developing appropriate strategies.
FSANZ’s document The Analysis of Food Related Health Risks provides more information about risk analysis at FSANZ.
How is the dietary exposure assessment used?
At FSANZ we use dietary exposure assessments to predict the risks of chemicals in food, including:
- for setting or amending food standards
- to estimate the public health impact of an existing chemical in the light of new information, such as revised reference health standards or new concerns about an established product
- ongoing monitoring and surveillance
- food recalls
- the development of food information tools and labelling
- the production of food consumption advice for consumers
- international training on risk assessment.
After the risk assessment process is completed, we are able to make risk management decisions guided by the findings from the scientific risk assessment. Risk management also takes other factors, such as social, economic and political factors, into account.
What data are required for a dietary exposure assessment?
The two main data sets are:
- food chemical concentration data (e.g. maximum use levels from standards, proposed levels of use, manufacturers use data, analytical survey data)
- food consumption data (e.g. national nutrition survey data).
You can find out more information on the food consumption data FSANZ uses, including national nutrition survey (NNS) data, in the food consumption data information sheet.
Also essential for the majority of assessments are:
- body weight information
- age and gender information
- reference health standards.
FSANZ tries to use up to date data where required for each assessment but we have to make some assumptions during the assessment where there are data gaps. If we are unable to include new data quantitatively in the exposure assessment, we can still use the new data to validate other data or the results obtained.
How does FSANZ ensure the data used are reliable?
The food consumption data we use are from national nutrition surveys and are the most comprehensive and up to date data in Australia and New Zealand. Australia and New Zealand are among only a few countries in the world that have this type of good quality data that allows dietary exposure assessments to be conducted. FSANZ has identified some analyses that show consumption amounts of major food groups do not change dramatically over a long period of time. Within a food group, consumption of specific or ‘niche’ products may, however, change a lot. Wherever possible, FSANZ collects more current data on these foods (such as market sales) to be used in some way in the exposure assessment.
How does FSANZ calculate dietary exposure?
At FSANZ we use internationally accepted procedures for estimating dietary exposure to food chemicals. To do the dietary exposure estimate calculations, we use a custom built computer program called DIAMOND. For more information on DIAMOND see the separate fact sheet.
We use many different dietary modelling approaches depending on the assessment, the data available, the questions that have to be answered and the type of food chemical.
In the majority of our assessments we use the food consumption data from each person in the national nutrition surveys to estimate their individual dietary exposure. Population summary statistics such as the mean exposure or a high percentile exposure are derived from each individual person’s exposure.
What are reference health standards and where do they come from?
Some reference health standards indicate the amount of a food chemical that people eat over a lifetime without any appreciable risk to health. For example:
- acceptable daily intake (ADI) for food additives and agricultural and veterinary chemical residues
- provisional tolerable weekly intake (PTWI) or daily intake (PTDI) for contaminants
- upper level of intake (UL) for nutrients.
For nutrient risk assessments we need to consider both the safety and adequacy of intakes, and also make sure that the reference health standards that relate to both adequacy (e.g. estimated average requirement (EAR), suggested dietary targets) and safety (UL) are used where appropriate.
The most robust reference health standard available should be used in dietary exposure assessments. Wherever possible, we use reference health standards set by international food regulatory agencies or other reputable bodies, such as those set by the WHO/FAO Joint Expert Committee on Food Additives (JECFA) and Joint Meeting on Pesticide Residues (JMPR) and the National Health & Medical Research Council (NHMRC Nutrient Reference Values for Australia and New Zealand, 2006). Where necessary, we will independently establish reference health values.
If there is no reference health standard, FSANZ will try to identify another level to which we can compare dietary exposure estimates. In some cases, it may not be possible to complete the risk characterisation step.
How does FSANZ know if an estimate of dietary exposure is a problem or not?
When interpreting dietary exposure assessment results FSANZ takes into account many things. Firstly, we compare the estimated dietary exposures to relevant reference health standards. We then take into account the quality of the data we have used to conduct the assessment, the assumptions we made, the toxicological data, the frequency of exposure, exposure from other non-food sources where relevant, the length of time for toxicological effects, population groups most effected etc. The level of risk is not solely determined by a single resulting number.
For more information:
See the fact sheet “DIAMOND ” about the FSANZ dietary exposure assessment computer program, or the FSANZ document “Principles and Practices of Dietary Exposure Assessment for Food Regulatory Purposes ”
Or contact the FSANZ Dietary Modelling Team at http://www.foodstandards.gov.au/contactus/contactform.cfm