Wednesday, 8 October 2008

Trouble with melamine and why trickery went unseen

SOURCE: The Dominion Post

What's this melamine, then? It's a white powder looking very much like flour or milk powder.

Where does it come from? Most melamine is a byproduct of the farm fertiliser urea. Fifty million tonnes a year of this chemical are made at gigantic industrial plants in 70 countries but mainly in China and India.

Industrialists can turn melamine into endless products such as concrete strengtheners, insecticides, printers' ink, fire retardants, detergents, glues, and a drug used for treating sleeping sickness. But a lot of it is turned into a very hard heat-resistant plastic that is used to make formica, counter tops, breadboards, garden ware, fabrics, wrapping plastics, tools, chairs, bins, dolls, picnic sets, chopsticks, and even Buzzy Bee cups and plates for kids. Melamine tableware once enjoyed a certain techno-panache and was quite expensive. These days you buy these lines at the $2 Shop.

Now we all know that unscrupulous Chinese milk suppliers have been adding melamine to watered-down milk on a colossal scale with catastrophic effects. Their trick went undetected for a long time because normal chemical checks on milk did not detect the adulteration.

To understand why, you must know that proteins, milk and meat pies contain large amounts of the element nitrogen. Technicians measure the amount of nitrogen in them as an indication of their protein content. Melamine also consists largely of nitrogen and, if sneaked into meat or milk, makes them appear to have more protein.

Alerted by the Chinese scandal, the New Zealand Food Safety Authority has rushed to test infant formula and other milk-derived products here. Using more sophisticated chromatographic analytical techniques, the authority has tested 72 samples of Heinz, Nestle, Holle, Babynat, Karicare, Wyeth's, Novalac and Probiotic baby milk formulas and found them all melamine-free. Other products tested include dietary supplements such as body- builders and geriatric formulas, sweets and components in animal foods. The authority has pulled Chinese White Rabbit Creamy Candies off store shelves because they contained too much melamine.

In recent weeks the authority has been exchanging information with similar agencies in the United States, Australia, Europe, Canada and elsewhere discussing how much melamine can be safely ingested. They have settled on 5 parts per million for food ingredients, 2.5 ppm for food in its final form and 1 part per million for infant foods. Any more melamine will trigger further investigation.

Among the many products sampled by the Food Safety Authority has been the pharmaceutical lactoferrin, which is made from milk. Minute amounts of melamine have been detected in the product but not enough to be a health hazard. Scientists at the authority are trying to work out how the lactoferrin was contaminated – possibly by leaching from plastic used in processing or packaging the product, or possibly from a farm pesticide residue.

So far, only trifling amounts of melamine, bordering on the limits of detection, have been detected in 116 samplings of New Zealand dairy products.

This is very reassuring, but a sharp eye must be kept on Asian imports.


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