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AgVetLink: Number 67, April 2008

New Zealand Total Diet Survey

Planning for the 2009 New Zealand Total Diet Survey (NZTDS) has commenced and a media release announcing this was made on 6 March 2008.

Assesses exposure to residues, contaminants, selected nutrients

New Zealand undertakes a TDS approximately every 5-6 years. The primary focus is to assess exposure to chemical residues, contaminant elements and selected nutrients, from approximately 120 representative foods, across the average diet of different age-sex groups within the New Zealand population.

A distinguishing characteristic of TDSs, including the NZTDS, is that foods are analysed on an ‘as consumed’ basis (e.g. banana, peeled; meat, cooked). This provides an assessment of any potential risk to the consumer at the point of consumption of the food.

Key features from 2003/04 to be included

The last NZTDS was undertaken in 2003/04 (published December 2005) and the 2009 NZTDS is expected to include the same key features of the 2003/04 survey in respect of the foods sampled and the age-sex population groups for which dietary exposures will be estimated.

Each food will be sampled twice during the 2009 calendar year in four sampling rounds – two for ‘national foods’ (those that are the same everywhere in New Zealand and are purchased in one location) and two for ‘regional foods’ (those that are locally produced and are sampled from Auckland, Napier, Christchurch and Dunedin).

Specific TDS tests

The specific tests that form the core of the NZTDS are:

• gas chromatographic multi-residue agricultural compounds screen (over 200 agricultural compounds)

• dithiocarbamates (DTCs) – the most commonly used fungicides in New Zealand

• four contaminant elements – arsenic, lead, cadmium and mercury

• two nutrient elements – iodine and selenium, which are naturally low in New Zealand.

The 2009 NZTDS is expected to focus on these core tests with the likely addition of extra analysis related to iodine (given our very low intakes) and sodium (the vehicle for iodine fortification but also at a high intake level which leads to other health problems).

International contribution

The NZTDS contributes to international commitments and obligations, such as the World Health Organization Global Environmental Monitoring Systems Food programme (WHO GEMS/Food), Codex Alimentarius and the WHO/FAO Joint Expert Committee on Food Additives (JECFA), and WHO/FAO Joint Meeting on Pesticide Residues (JMPR).

The NZTDS also provides valuable information that can contribute to the review of Maximum Permissible Concentrations (MPCs) in food with Food Standards Australia New Zealand and the setting of maximum residue limits (MRLs) for agricultural compounds and veterinary medicines by NZFSA.