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Chief Executive’s column

In our last Food Focus, I talked about my intention to write a new website column that would provide background and insight into the decisions NZFSA makes. The column would be designed to help people understand the science that has underpinned our decision making, why we have reached the conclusions we have, and any risks involved.

Unfortunately before we reached that task, the problems with melamine in foods in China arose and we were all a little distracted here! It seems appropriate therefore to make melamine our first topic and to look at the reasons for decisions we have made in regard to this issue.

Before the recent events, little was known about the effects of melamine on humans. However, internationally it was recognised that this chemical is part and parcel of our life today, leaching from plastics and contact materials during processing and packaging in trace quantities, and the European Union had an allowance of up to 30 ppm in foods and a number of other countries had similar measures.

Food safety authorities internationally believed that at these levels it could be considered to have few ill effects. This seems to have been confirmed from the China event, where the levels found in milk in China were up to 1800 ppm but older children and adults seemed to come to little harm. Ill effects were largely confined to infants and toddlers where milk was often their primary or only source of nourishment.

When the concerns arose worldwide, the science upon which we could base our decision making was sketchy. This is not a product usually found at high levels in food, but from research in the United States into the problems last year associated with melamine in animal feed, it appeared possible that the mix of melamine and cyanuric acid together may have led to the kidney problems that caused the death of so many pets. But this was speculation and not definitive.

It was clear that eliminating melamine from our food completely was not practicable and given the fact that it did not cause harm at low levels, imposing a requirement for zero presence was not necessary. However NZFSA, along with other food authorities around the world, needed to define what was to be our ‘trigger level’ for investigation and action if appropriate. While any incidents of adulterated food would obviously be dealt with urgently and firmly, we needed to recognise that melamine from packaging, plastic equipment used in food preparation and storage or even from kitchen benchtops could be present quite innocently and do no harm.

As on other similar occasions, NZFSA worked in close cooperation with food safety authorities in Australia, Canada, Europe and the United States as well as the World Health Organization and elsewhere to determine what would be the level at which we would investigate and act if necessary.

The European Food Safety Authority reconsidered its opinion on the estimated daily intake of melamine that people could safely eat without suffering any harm. (This is called the Tolerable Daily Intake or TDI – a measure commonly used to assess how much of any substance people can consume.)

They reconfirmed that for every kilogram a person weighed, they could safely consume 0.5 milligrams of melamine every day. This meant a 20 kilogram child could safely consume 10 milligrams of melamine every day of their life and suffer no ill effects. For a 70 kilogram adult, the safe amount would be 35 milligrams of melamine every day. This TDI also includes a very wide safety margin.

Based on this figure, which is very close to that of the United States, NZFSA decided to adopt a melamine risk management strategy including setting a conservative investigation threshold of 2.5 ppm for most foods. We believed infant formula to pose a greater risk and set the threshold at the routine level of detection at which we can be confident of results and that is at 1 ppm. This would mean that even if a person was to eat very large amounts of product contaminated at these levels, they would not suffer any harm.

It was decided that, if NZFSA detected amounts above these levels, a risk assessment will be undertaken, taking into account how much melamine is in the food and how much is likely to be eaten in a day. If consumption levels of the food could be expected to be high enough for people to exceed the 0.5 mg/kg bodyweight tolerable daily intake, or there was a suspicion of deliberate adulteration of the food, then we would need to take action. Our spreadsheet shows the results of this sort of assessment.

Decision making in the absence of complete information or knowledge is not uncommon for food safety authorities and a conservative approach will always be applied, but it was clear that applying a zero tolerance would have been scientifically unsustainable and resulted in huge costs and a waste of safe food. The strategy adopted provides a sensible compromise.

We will continue to work with our counterpart agencies and, should new information or emerging science indicate change is needed, then we will review the strategy to ensure New Zealand food continues to be safe.

Last updated 11 November 2008