Information Paper

Dietary Exposure Assessments At FSANZ

What is dietary modelling?

Dietary modelling is the technique of combining food consumption data with food chemical concentration data to estimate dietary exposure (intake) to food chemicals. In a dietary exposure assessment, estimated dietary exposure to a food chemical is compared to an established reference health standard. In this document, food chemical refers to food additives, contaminants, agricultural and veterinary drug residues and nutrients.

How is dietary modelling used at FSANZ?

Dietary modelling may be used within a broader framework of risk assessment and management in the development of national and international food standards:

• to predict the risks associated with chemicals in food;
  
  
• to estimate the public health impact of an existing chemical in the light of new information such as revised  standard reference values or new concerns about an established product;
  
  
• ongoing monitoring and surveillance;
  
  
• food policy formulation; and
  
  
• development of food information tools and labelling.

How do we predict risks of exposure to food chemicals?

The scientific risk analysis of chemicals in food, undertaken in the development of national and international food standards, comprises three major components (see diagram overleaf).

• Risk assessment
  
  
• Risk management
  
  
• Risk communication

The risk assessment process

Dietary exposure assessments are used to assess the potential risk to health associated with proposed changes to the food supply. Such assessments are a crucial third step in the risk assessment process and may also be useful in identifying risk management options and developing appropriate strategies.

In the first step of risk assessment (hazard identification) potential adverse effects from the chemical are assessed. In the second step, (hazard characterisation) the dose of the chemical that is a problem is determined, and reference health standards may be set. The third step of exposure evaluation determines the amount of the chemical that populations may be exposed to from all sources, including the diet, water and the environment. In the fourth step of risk assessment (risk characterisation) the estimated exposure, including dietary exposure, is compared with the reference health standard for the particular food chemical.

Reference health standards for food chemicals

Reference health standards indicate the amount of the food chemical that can be ingested from the diet and other sources every day over a lifetime without any appreciable risk to health.

• Acceptable daily intake (ADI) for food additives and agricultural and veterinary chemical residues
  
  
• Provisional tolerable weekly intake (PTWI) or daily intake (PTDI) for contaminants
  
  
• Recommended dietary intake (RDI) for nutrients

For nutrients, the RDI indicates the amount of the nutrient considered to be adequate, on the basis of available scientific knowledge, to meet the known nutritional needs of practically all healthy people. Some nutrients that have a relatively small gap between the minimum requirement for health and an upper toxic level may also be considered a contaminant (eg copper, zinc, selenium).

Risk management

After the risk assessment process is completed, risk management decisions are then made on the basis of the findings from the scientific risk assessment process, taking social economic, political and other factors into account.

Risk Analysis Process

Using DIAMOND For Dietary Modelling

The DIAMOND (DIetAry Modelling Of Nutritional Data) computer system, used for dietary modelling at FSANZ is programmed using the SAS software system.

DIAMOND requires two main sets of data to run dietary models:

1.       the concentration of the food chemicals in specific foods, and

2.       data on the food consumption levels of those foods and the bodyweight information of the consumers (see diagram overleaf).

Where does the food chemical concentration data come from?

• Maximum permission levels from food standards (FSANZ, international Codex standards, European Union standards)
  
  
• maximum permitted level (MPL) for food additives
  
  
• maximum residue limits (MRL) for residues
  
  
• maximum levels (MLs) for contaminants 
  
  
• Trial data (agricultural and veterinary chemicals);
  
  
• Survey data (e.g. total diet surveys, government surveillance surveys);
  
  
• Manufacturers' data for the level of use (food additives); or
  
  
• Food composition tables (nutrients).

What food consumption data is used?

This information is derived from the following national nutrition surveys from both Australia and New Zealand.

• 1983 Australian National Dietary Survey (NDS) for adults
  
  
• 1985 Australian National Dietary Survey (NDS) for schoolchildren (10-15 years)
  
  
• 1995 Australian National Nutrition Survey (NNS) for 2-70 + years
  
  
• 1997 New Zealand National Nutrition Survey (NNS) for 15+ years.

Options exist within DIAMOND for running models using different food consumption data and food chemical data.   Models can also be run for different age/gender groups or groups with different dietary patterns.

Contact for more information:

For more information please contact diamond@foodstandards.gov.au

How Is DIAMOND Used In Dietary Exposure Assessments?

The following schematic diagram outlines the process of conducting a dietary exposure assessment using DIAMOND, from the initial steps of selecting a food chemical and population group to assessing the health risk of exposure for that population to the chemical.

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