Giving consumers peace of mind

Dicyandiamide (DCD) is an active ingredient sprayed on farm pastures to slow or inhibit nitrate production and hence increase pasture growth. Ammonium salts form from cows’ urine and normally produce nitrate through bacterial action in the soil. The DCD chemical, a nitrile, was developed 30 years ago and is used in electronics, pharmaceuticals, food packaging and epoxy adhesives. It has been researched thoroughly and to date has posed no food safety concerns. However, after the publication of a Wall Street Journal article last week which questioned the safety of this country’s milk, world newspaper headlines such as these in the Chinese press: ‘‘NZ milk is poisonous’’ and ‘‘Chinese-made milk free from DCD’’ followed.

Here we saw the effect of politics and science. The news alarmed some consumers, who were still concerned after the melamine scandal, to such an extent that many requested their money back from previous milk product purchases. Several retailers hiked their prices for French, Dutch and Australianmade infant formula because of demand increase from buyers wary of New Zealand products.

This reaction was short lived after a Fonterra executive and New Zealand’s ambassador to China held a press conference in China last week. They explained the situation more clearly regarding the ‘‘less than a hundredth’’ of the recommended daily acceptable levels uncovered in newly instituted routine tests, under European food safety limits.

It is a fact that today analytical instrumentation and methods allow scientists to detect, identify and measure much lower concentrations of ingredients in a wider range of substances than ever before. This means that we will continue to make more discoveries about lowlevel constituents found in most food products. One only has to examine the very large numbers of very low-level constituents (more than a hundred) found to make up a ‘‘natural’’ product such as wine, to appreciate that even a simple fermentation reaction on grapes can produce a very complex mixture, not just alcohol and sugar.

Cows ingest pasture and more than 60 per cent of the nitrogen is returned to the pasture through concentrated urine patches. Much of this nitrogen is leached back into the environment. Application of DCD to a pasture in the rainy season has been found to inhibit nitrification, the process where ammonium salts produced from mineralisation of animal urine (in a few days) are converted to environmentally damaging or problematic nitrate ions.

DCD inhibits nitrification by blocking the enzyme that causes oxidation of ammonium to nitrate in soil, thereby slowing down the release of nitrate to water bodies, and the production of nitrous oxide via the process of denitrification.

Nitrous oxide is a potent greenhouse gas. By retaining the ammonium form of nitrogen for a longer period in the pasture, farmers gain the benefit of better pasture growth and productivity, and lower emissions of greenhouse gases as well as reduced water and environmental pollution.

This improves farming methods to produce milk more efficiently for the benefit of society. However, its presence in milk products for babies has alarmed consumers who understandably do not want residues in the food they feed their children.

The withdrawal of the use of DCD in fertiliser will have an effect on the environmental cleanup.

It may create a more satisfied market, even though the science suggests there is little to be concerned about health-wise. From a greenhouse gas viewpoint, we have a long and difficult way ahead to be able to sustainably feed and raise the wealth of more than 7 billion people.