1080 poison tests continue

Police have visited 4140 businesses to give advice, including 1935 dairies, 606 pharmacies and 556 petrol stations. Photo / Nick Reed

Police scientists are still poring over samples to identify who was behind threats to contaminate infant formula with 1080 poison.

It is five months since Fonterra and Federated Farmers received the original blackmail documents, which contained samples of contaminated formula, and two months since the public was made aware of the threats.

Despite rigorous testing and public feedback, including hundreds of responses over potential leads, those responsible have not been caught.

Those making the threats set a March 31 deadline to end the use of 1080 as a pest control method.

That deadline passed 47 days ago, but police said that should not breed complacency.

"We urge the public to be vigilant and report anything suspicious, and we continue to appeal for anyone with information to contact police," deputy commissioner Mike Clement told the Herald on Sunday.

He said up to 35 staff were working on the case. So far, 154 calls have been made to the 0800 Operation Concord freephone number and more than 260 emails have been received.

Police have visited 4140 businesses to give advice, including 1935 dairies, 606 pharmacies and 556 petrol stations.

Fonterra's global ingredient managing director, Kelvin Wickham, said no orders had been cancelled or deferred.