Food safety officials are scrambling to determine the extent to which New Zealand-made foods have been contaminated with the toxic chemical melamine which has poisoned thousands of Chinese babies.
At least one New Zealand manufacturer has admitted producing food products contaminated with melamine.
"A New Zealand company undertaking precautionary testing has. . . found a minute amount of melamine in one of its highly processed products," the New Zealand Food Safety Authority (NZFSA) said last night.
The authority is also pulling Chinese White Rabbit Creamy Candies off New Zealand shelves as they contain unacceptably high levels of melamine.
The lollies are apparently made with Chinese milk and tests have shown they contain 180 parts per million of melamine.
"This product contains sufficiently high levels of melamine which may, in some individuals, cause health problems such as kidney stones," the authority said.
"The levels we have found in these products are unacceptable."
People worried they may have eaten the sweets should seek medical advice, it added.
"This is a serious concern," NZFSA deputy chief executive Sandra Daly said in a "privileged statement" which protects the organisation from lawsuits.
"We cannot discount the likelihood of health risks resulting from the consumption of these sweets"
The sweets appeared to come from a number of manufacturers through a range of importers.
The tainted milk scandal in China came to light after milk powder sold by various companies including New Zealand dairy giant Fonterra's Chinese partner San Lu was found to be contaminated with melamine.
In New Zealand-made foods one potential contamination pathway the authority is expected to check is whether the melamine is a residue from pesticide sprays.
Chan King-ming, an associate professor of biochemistry at a Chinese university, told the New Scientist magazine yesterday that cyromazine, a derivative of melamine, has been widely used in China as a pesticide.
In New Zealand, cyromazine has been used in a pesticide called Veterzine, and in June, the NZFSA published a list of contaminant levels it will allow in animal products, and specified a maximum permissible level of cyromazine and melamine in 0.3mg/kg in sheepmeats, and 0.15mg/kg in poultry and eggs.
According to Prof Chan, cyromazine is absorbed into plants as melamine and has spread through the food chain in animal feeds.
"It is not just in milk products, but also in farm products and animal feed, fish diet," he said.
Associate professor in applied biology and chemical technology at Hong Kong Polytechnic University Peter Yu said that though it was known melamine caused kidney stones and problems in the kidney, there could also be other ill effects in the longterm.
"These are ingredients that shouldn't be in food," he said.
NZFSA said the un-named manufacturer who found melamine in the NZ-made product claimed that similar levels are being found in the same product produced in other countries. NZFSA did not specify the food, but downplayed the significance of the find for perceptions of NZ food safety.
It suggested that the low levels of melamine reported could be a "coincidental consequence" of the manufacturing process.
NZFSA has said its officials are waiting on a European Food Safety Authority (EFSA) scientific opinion on risks to human health associated with melamine in products that may have a low level of contamination.
There is a generally accepted "tolerable daily intake" of melamine in food in the EU (0.5mg for each kg of body weight daily) and in the US (0.63mg/kg of body weight/day).
But the NZFSA's principal adviser on toxicology, John Reeve, said that while the agency is aware of tolerable daily intake levels set by the EFSA and the US Food and Drug Agency (FDA) it had not acceptable daily intake for New Zealand.