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Dietary exposure and intake assessments

(May 2014)

Dietary exposure assessments and intake assessments are an important part of many Food Standards Australia New Zealand (FSANZ) risk assessments.

A dietary exposure assessment is the process of estimating how much of a food chemical a population, or population sub group, consumes. FSANZ uses internationally accepted ‘dietary modelling’ techniques to conduct dietary exposure assessments. These assessments consider the potential exposure of the Australian and New Zealand populations to chemicals like food additives, pesticide residues, chemical contaminants, nutrients, food ingredients and other substances that have a nutrition or health purpose.
 
Dietary exposure to (or intake of) food chemicals is estimated by combining food consumption data with food chemical concentration data. The term ‘dietary intake assessment’ is used to refer to nutrients and other substances that have a nutrition or health purpose.
 
At FSANZ we may compare the estimated dietary exposure to a food chemical with a known health-based guidance value, for example, an acceptable daily intake (ADI) for a substance is the amount of that substance that can be consumed daily without adverse health effects. Comparing estimated dietary exposures to these values is done to work out the level of risk to the population.

Terminology

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 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, pesticide and veterinary drug residues, novel ingredients, nutrients and other chemicals in food (e.g. caffeine). It does not include micro-organisms.

How is the dietary exposure assessment used?

Dietary exposure assessments are a core part of our scientific risk assessment process to characterise potential risks from chemicals in food for a range of purposes, including:
  • setting or amending food standards
  • estimating the public health effect of an existing chemical in the light of new information, such as revised health-based guidance values or new concerns about an established product
  • ongoing monitoring and surveillance
  • food recalls
  • the development of food information tools and labelling
  • the development of food consumption advice for consumers.
A risk assessment is part of our risk analysis process. After the risk assessment is complete, we can make risk management decisions, guided by the findings from the risk assessment, on how to manage any potential risk associated with the food chemical. Risk management also takes social, economic, political and other factors into account. Examples of risk management might be food regulatory standards, food labelling or consumer information.

Data

The two main data sets used in a dietary exposure assessment 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 for the populations of interest (e.g. national nutrition survey data). 
 
Other essential information for most assessments includes:
  • food consumers’ body weight information
  • food consumers’ age and gender information
  • relevant health-based guidance values.
FSANZ uses the most up-to-date data available for each assessment but we sometimes have to make some assumptions when there are data gaps. Any limitations of assessments or assumptions made are clearly outlined in our reports.

How does FSANZ ensure 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 using individual dietary records from the national surveys. Analysis of food consumption patterns over time indicate consumption amounts of major food groups do not change dramatically over a long period of time. In 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 support assumptions made in the dietary 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. Read more about our computer program.
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 most assessments we use the food consumption data from each person in a national nutrition survey to estimate their individual dietary exposure. Population summary statistics such as the mean exposure or a high percentile exposure are then derived from the individual person’s exposures.

What are health-based guidance values and where do they come from?

Some health-based guidance values indicate the amount of a food chemical that people can eat over a lifetime without any appreciable risk to health. For example:
  • acceptable daily intake (ADI) for food additives, agricultural and veterinary chemical residues 
  • provisional tolerable monthly intake (PTMI), provisional tolerable weekly intake (PTWI) or provisional tolerable 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 health-based guidance values that relate to both adequacy (e.g. estimated average requirement (EAR), adequate intake (AI)), suggested dietary targets and safety (measured via the upper level of intake or UL) are used where appropriate.
 
The most robust health-based guidance values available should be used in dietary exposure assessments. Wherever possible, we use health-based guidance values set by international food regulatory agencies or other reputable bodies, such as the World Health Organization/Food and Agricultural Organization Joint Expert Committee on Food Additives (JECFA) and Joint Meeting on Pesticide Residues (JMPR), or by the National Health and Medical Research Council (NHMRC) nutrient reference values for Australia and New Zealand. If necessary, we will independently establish health-based guidance values.

How does FSANZ know if an estimate of dietary exposure is a problem?

FSANZ takes many things into account when interpreting dietary exposure assessment results. We compare the estimated dietary exposures to relevant health-based guidance values. We then take into account the quality of the data we have used, the assumptions made, the toxicological data, the frequency of exposure, exposure from non-food sources where relevant, how long before a toxicological effect would occur, population groups most effected etc. The level of risk is not solely determined by a single number from our calculations.
 
To make sure we were using the best processes and practices for estimating dietary exposure we had an international peer reviewer evaluate our work in 2006‒07. Read the review report

More information

 
Risk Analysis in Food Regulation (for more information about the use of health-based guidance values in FSANZ risk assessments and how we interpret our dietary exposure assessments).
 
 
 

 

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