Authorities went public with the discovery yesterday even though the residues of the nitrification inhibiting product dicyandiamide or DCD was first detected by Fonterra in September.
There are no known health safety risks associated with DCD but the Primary Industries Ministry said the detection of low levels might present a trade issue.
Fertiliser companies Ravensdown and Ballance AgriNutrients voluntarily withdrew their products from sale yesterday.
Ballance said it had not sold its DCD-based product Dcn since last July and not promoted its use on pastures since late 2010.
The ministry says DCD is a non-toxic water soluble compound that degrades to form carbon dioxide, ammonia and water, and internationally is also used in electronics, pharmaceuticals and food packaging.
It was released in 2004 after Landcare Research had trialled it.
Ministry deputy director general standards Carol Barnao said consumers had high expectations of New Zealand food and regulations to ensure its quality and safety.
“The crux of this is that there is no internationally set standard for DCD residues in food. This is because DCD has not been considered to have any impact on food safety,” she said.
“Because no standard exists, the detectable presence of DCD residues in milk could be unacceptable to consumers and our international markets, even in the small amounts found in recent testing.
“Food regulators around the world are reflecting market demands with increasingly rigorous testing and in some countries there is a zero tolerance to detected residues outside agreed standards.
“New Zealand’s reputation is based on the high quality of food we produce, so MPI is working across the board with primary producers to manage potential concerns for our markets and consumers.”
She said the ministry had set up a working group with the industry in last month to assess the use of DCD after the ministry was advised in November of the occasional presence of low levels of DCD in dairy products.
The detection coincided with the times of the year that DCD was applied: in autumn, winter and spring.
The ministry undertook testing of 48 random raw milk supplies in 2010 but no residues were detected then.
Further testing last September by Fonterra confirmed DCD residues were present in some milk powder, skim milk powder and buttermilk powder but they did not show up when tested again in November.
DCD had not shown up in butter, cheese or milk fat.
The ministry said testing indicated that if DCD use was suspended before the next application was due, no more milk products would contain DCD residues.
The Fonterra Shareholders Council urged regional councils to re-examine nitrate level targets given the decision to suspend DCD.
Council Chairman Ian Brown said farmers and councils had been working hard to develop plans for reducing nitrate levels and on farm greenhouse gas emissions, and DCD was identified as an efficient way of achieving these.
“The outcome is disappointing for all stakeholders and will affect the ability of around 400 farmers to meet the nitrate level targets which were set based on the ongoing use of DCD – targets they have been working hard to meet,” he said.
Frequently asked questions – voluntary suspension of DCD
Related story: DCD suspended over trade issues
