By the time Westland Milk was told, Fonterra had already put extra tests in place and the Ministry for Primary Industries (MPI) had developed a test to identify the poison in milk products.
MPI did not directly answer a question on why Westland Milk was not told sooner, but said: "In recent weeks we informed manufacturers, global infant formula companies, grocery distribution companies and retailers [including supermarkets] of the threat. Westland Milk was advised at the same time as these manufacturers. We have advised all of them so they could put in place additional measures, including extra security."
Westland Milk is based in Hokitika on the West Coast, which has been a hotbed of anti-1080 protests over the years, including a 2007 incident in which letters containing 1080 poison were posted to the Westport Department of Conservation office and the West Coast Regional Council offices in Greymouth.
Rod Quin, chief executive of Westland Milk Products, said the company "already had robust security measures in place" before the 1080 threat was made. It had "to do little to further boost those, other than to advise shareholders and staff to be even more vigilant".
In a statement Synlait said it was "confident our food safety systems and security standards protect the integrity of our products" but had added extra measures.
Security at Synlait plants already included fully fenced sites with electronic gates, comprehensive CCTV coverage and swipe-card access to key areas, the company said.
A Fonterra spokesman said it would not disclose details of its security measures, and directed all such questions to MPI. In a statement, MPI said the manufacturing and distribution chain for infant and other formula "is extremely secure".
Information hotlines
If you have any questions about what to feed your baby, call Plunketline 0800 933 922 or Healthline 0800 611 116
For more information go to foodprotection.govt.nz