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New Zealand Total Diet Survey report released

24 February 2006

The New Zealand Food Safety Authority (NZFSA) today released its final report on the 2003-4 Total Diet Survey (TDS).

The survey, a four-year project which is carried out every five or six years, tests more than 120 foods most commonly eaten as part of a typical Kiwi diet, to determine the concentrations of agricultural compound residues, contaminant elements (arsenic, cadmium, lead and mercury) and nutrient elements (iodine, iron, selenium and sodium). Its findings provide a snapshot of the dietary exposures that most New Zealanders are subject to in the food they eat.

Key findings from the report show that:

• of the 200,000 individual tests carried out as part of the study, only 997 showed any detectable residues, all well below their Acceptable Daily Intake (ADI) limits

• New Zealanders enjoy among the lowest lead exposures in the world. Dietary exposure to lead has reduced overall – a likely result of the introduction to New Zealand of lead-free petrol in 1996

• most Kiwis enjoy very low exposures to all the contaminant elements

• the average Kiwi diet is high in salt and low in iodine

• women aged 25 and over are consuming only half the Recommended Daily Intake (RDI) of iron.

NZFSA’s TDS project manager Cherie Flynn says: “We are very pleased with the results and the overall trend toward lower levels of agricultural residues and contaminants, particularly as agricultural compounds are commonly used in agriculture. The survey provides proof that consumers need have no concerns about the safety and suitability of New Zealand food. However, we also note the decline in levels of nutrients that New Zealanders are consuming, and we will continue to monitor this.”

The TDS was conducted by the Institute of Environmental Science and Research for NZFSA. Food samples are bought in four quarters over a year, to provide for seasonable variation, and test results were cross-referenced by sex and age range against data from the Ministry of Health’s nutrition surveys.

The food was tested on an ‘as consumed’ basis – meaning bananas were peeled and meat was cooked – to give researchers the clearest picture possible of the potential risks to consumers at the point at which the food is eaten.

Overall, of the 990 food samples screened for 221 agricultural compounds, half contained detectable residues (down from 59% in the 1997/98 TDS). Cherie says: “This is particularly pleasing because this time we were screening for more compounds (221 compared with 90 in the 1997/98 survey) and advances in technology enabled us to detect even lower levels of some compounds.”

Of the almost 200,000 individual results there were 997 detectable residues (down to 0.5% compared with 1.4% in the previous survey).

“Estimated dietary exposures to agricultural compound residues were well below ADI, with 66% having no detectable exposure and 90% being less than 0.1% of the ADI,” says Cherie. “Of the highest exposures, just 0.5% were between 5% and 20% of the ADI over any of the age-sex groups, including 6-12 month-old infants. Persistant organochlorine concentrations continue to fall and are, at most, 1% of the ADI and most of the time far lower than that.”

The news is generally all good for environmental contaminants, too. Intakes for most New Zealanders of arsenic, cadmium, lead and mercury are mostly well below Provisional Tolerable Weekly Intakes (PTWI).

The survey showed that New Zealanders enjoy among the lowest lead exposures in the world: exposure among 19-24-year-old males was just 3.8% of the PTWI, rising to just 12% for 6-12 month-old infants. Lead levels in the environment (and food) have dropped continuously since the removal of lead from petrol and paint.

Dietary exposure to arsenic was less than 4% of the PTWI and mercury exposure – dominated by fish and related products – was below 26%. Cadmium exposures are estimated at 37% of the PWTIs for children in the 5 to 6 and 1 to 3-year-old age groups, and lower still for the other groups, though this can be influenced by the number of oysters consumed. “Those who eat very large numbers of oysters are exposed to higher cadmium levels but even so, the potential risk to health remains low,” says Cherie.

Low dietary exposures to several nutrients are a problem for some groups. “New Zealand soils are low in iodine, and this, along with reduced use of iodised salt and salt in general, mean that iodine intake varies from 57% of the RDI for males over 25 to just 40% for females over 25,” says Cherie.

Iron intakes are generally low for children across all groups up to the age of six, and women over 25 are consuming just over half (51%) of the RDI.

Meanwhile, mean daily sodium intakes are significantly above the acceptable intake for all age-sex groups. They exceed the upper intake limits for males and females over 25, 19-24 year-old males and for 11-14-year-old boys and girls by up to 125% for the average consumer. This is more than double the Upper Intake Limit (UIL), making sodium consumption among these groups higher than that of the UK, France and the USA. “The good news is that, in some of the age-sex groups with high intakes, the trend over the past three TDSs has shown a slow decline,” says Cherie.

Interim results from each of the four quarters of the TDS survey were released as tests were completed, allowing NZFSA to respond immediately to any concerns. Two most notable were lead levels in baby custard – later traced to a chance contamination of bulk maize (the product was recalled) and extremely high levels of iodine found in a soy milk, which was subsequently reformulated to correct the problem.

“These incidences confirm that New Zealand’s food safety systems work well and can respond rapidly and appropriately when necessary,” says Cherie.

Now that NZFSA has completed publication of the results, work will begin on drawing up policy to deal with the most important issues. Work is already well underway on the low levels of iodine, with a review by Food Standards Australia New Zealand (FSANZ) on the fortification of the food supply in New Zealand and Australia.

Further information on the Total Diet Survey, including the final report as well as reports from each of the four quarters is available at: www.nzfsa.govt.nz/science/research-projects/total-diet-survey/index.htm.

Ends

For further comment contact Cherie Flynn, NZFSA Senior Policy Analyst, 04 463 2572.

For more information contact Gary Bowering, Manager (Communications), 04 463 2532 or

027443 2550.

More information on agricultural compounds in food is available from:

http://www.nzfsa.govt.nz/consumers/chemicals-nutrients-additives-and-toxins/agricultural-compound-in-food/index.htm.