A second milk company has found traces of an agricultural chemical in some of its milk and milk powder.
Products containing dicyandiamide (DCD) have been used by some dairy farmers to help prevent nitrogen leaching into waterways and reduce nitrous oxide gas emissions.
Last week two fertiliser companies withdrew their nitrification inhibiting products from the market, after Fonterra said it had discovered low-level residues in some of its milk and milk powder during testing in September last year.
Westland Milk Products says it started its own testing through an independent laboratory following the Fonterra announcement.
The tests revealed minute traces of DCD in samples produced prior to 1 November last year, but not in more recent samples.
Westland Milk chief executive Rod Quin said some customers in Asia have already requested tests for the chemical, and the company will do further testing and report the results as soon as possible.
The compamy says only a small number of its farmers have used DCD as a nitrification inhibitor on pasture, mostly outside peak production periods, and the small residues found are not a health risk.