The Prime Minister and the ministers with agriculture and food safety responsibilities thought long and hard before opting to stay quiet. It was a calculated risk.

It gave the police the time they asked for to hunt (unsuccessfully) for the perpetrators without alerting them to the investigation.

It enabled the Ministry for Primary Industries and the dairy industry to develop a testing system that has analysed about 40,000 raw milk and product samples without finding any 1080.

It enabled the industry to check the infant formula supply chain from farm gate to supermarket shelf to see whether any stages were vulnerable to contamination.

Taking those steps enabled Key and his ministers to say with a high degree of confidence that all infant formula lines were safe when the media finally got a tip and started asking questions.

The Government would not have been in that position had the public quickly become aware of the anonymous letters sent to Fonterra and Federated Farmers which contained small packages of infant formula laced with concentrated 1080.

Had that happened, there would have been absolute panic and the Government would have been desperately trying not look like a headless chook.

As it is, Key took a huge punt on whoever is responsible for the threat sticking to their timetable of possibly contaminating infant and other formula if 1080 pest control operations were not halted by the end of this month.

The risk that contamination might have been attempted earlier, resulting in the death of a child, would have left Key high and dry and in resignation territory once it became known that he had been aware of the threat.

Such a scenario would have made arguments over Key's promise to resign if the Government Communications Security Bureau was found to be conducting mass surveillance of New Zealanders look like chicken feed.

Key and company are not out of the woods yet. Sales of infant formula to about 75 countries are worth about $440 million annually.

Trade diplomats have alerted authorities in New Zealand's major export markets about the contamination threat. Fingers are crossed in the Beehive that infant formula will not be banned from markets such as China.

Even so, some products are expected to take a short-term hit, before recovering.

Coming after Fonterra's botulism scare two years ago and fluctuating international prices, this brush with "eco-terrorism" is one more thing the dairy industry doesn't need.