Police say people should continue to be vigilant when buying infant formula by checking all products for tampering.
They have confirmed formula from all tins thought to have been tampered with has tested negative for the pesticide 1080.
The tests were conducted because of reports from the public about damaged tins, in the wake of an anonymous threat to spike infant formula with 1080.
Assistant Police Commissioner Malcolm Burgess said the results showed any damage came from normal manufacturing or handling issues.
He said the infant formula in the tins that were tested was safe for infants to consume.
The Ministry for Primary Industries said information on how to check for tampering is available on its website and in supermarkets.
Spokesperson for the Ministry for Primary Industries Scott Gallacher said Ministry officials were working with manufacturers to ensure tight scrutiny of the entire supply chain for infant formula.