Foods we eat to be tested for toxins

Selecting nectarines at Centre City New World in Dunedin, for testing in the New Zealand Food Safety Authority total diet study, is Public Health South technical officer Peter Haslemore. Photo by Gerard O'Brien.
Selecting nectarines at Centre City New World in Dunedin, for testing in the New Zealand Food Safety Authority total diet study, is Public Health South technical officer Peter Haslemore. Photo by Gerard O'Brien.
How much of what we eat exposes us to chemical residues or contaminants, such as arsenic or mercury?

This is a question that will be answered over the next year as more than 120 commonly eaten foods are tested during the New Zealand Food Safety Authority's total diet study.

Sampling officers in Dunedin, Christchurch, Napier and Auckland began their first round of shopping this week and will be buying food for testing every three months from their local supermarket.

Senior programme manager Cherie Flynn said the foods tested would be representative of the general eating habits of most age groups.

They include fruit, vegetables, meat, dairy and bread, and Indian takeaways have been added for the first time.

"What makes this study unique is that the food is prepared to a table-ready form so potatoes are cooked and bananas are peeled."

The tests would be used to estimate New Zealanders' total dietary exposure to more than 250 agricultural compounds, such as drenches, fertilisers and pesticides, the contaminants arsenic, cadmium, lead and mercury, and the nutrients iodine and selenium.

Seafood and infant formula will also be tested for methylmercury.

Organic mercury, particularly methylmercury, was significantly more toxic than inorganic mercury, Mrs Flynn said.

"Infants are one of the most vulnerable groups in the population and infant formula is a big part of their diet. We do not expect to find significant levels of methylmercury in infant formula, but it is prudent to check."

A total diet study is carried out every five or six years and the last study in 2003-04 showed New Zealanders had some of the lowest lead exposures in the world, but the average Kiwi diet was high in salt and low in iodine.

"Previous total diet studies have found our food supply to be as good as any in the world, but we need regular testing to ensure our systems are performing as intended."

Quarterly results will be available throughout the year and a final report is expected in September 2010.