The Prime Minister has labelled the man who threatened to taint infant formula with 1080 pesticide "despicable", saying his imprisonment will come as a relief to families.
Businessman Jeremy Kerr was sentenced to eight years and six months in prison this morning.
His threat caused an estimated $37 million in costs, the High Court in Auckland heard.
Kerr was arrested last year after writing two letters threatening to poison infant formula with 1080 unless New Zealand stopped using the pesticide.
Fonterra was the first of 14 organisations to provide a victim impact statement to the court this morning.
Spokeswoman Maury Leyland said the direct threat to the company, farmers and the New Zealand economy was a huge concern.
"It's hard to imagine a worse threat, especially to children and their families."
The court heard Fonterra's response cost more than $20 million, and 9500 hours were spent trying to resolve the issue.
Ms Leyland told the court a number of employees came into contact with the 1080 sent in the letters, which was distressing for both them and their families.
Federated Farmers chief executive Graham Smith told the court the threat was a direct attack on the very fabric of society.
"It had the potential to devastate New Zealand's ability to operate in international markets," he said.
MPI head Scott Gallacher called the sentence a "true deterrent to anyone for anyone ever thinking about contaminating and purposefully seeking to injure and hurt people in our society".
"We had a credible threat that threatened our most vulnerable in society. From our perspective, we were not going to sit to one side and allow that threat not to be responded to."
Outside the High Court, Detective Superintendent Andy Lovelock said he was impressed with the work of police.
"Today's been a culmination of 14 months of hard police work to get to this point. It's been a very challenging investigation," he said.
"It was like looking for a needle in a haystack to start with, and the real question was whether we were in the right haystack.
"In court we identified 2600 people we believed were potentially of interest, and we managed to whittle it down to one."
Speaking to media this morning, John Key took a rare step of commenting on a court case saying he believed all New Zealanders would be relieved Kerr was behind bars.
"Most New Zealanders, in fact, I think all New Zealanders will be appalled by this gentleman's behaviour. To go out there for commercial and profiteering gain and put out the sort of scaremongering campaign and at least argue they're going to carry out the threats that could kill babies is just despicable behaviour.
He hoped it would be a "strong deterrent" for others considering doing the same thing.
The threats unfairly put "enormous stress" on families who were just trying to raise their children, he said.
Kerr previously pleaded guilty to two charges of blackmail.
It was revealed Kerr was behind a rival pesticide called Feratox, and sought to gain financially if 1080 was banned.
At a disputed facts hearing, Kerr said he wasn't anti-1080 but argued his motivation was to stop the "irresponsible distribution" of the poison.
But the court ruled money was what drove him to make the threats.
"It brings a close to a blackmail threat which put a lot of people under stress, and a lot of concern for mums and dads," says Mr Gallacher. "For us, this is a clear line in the sand that everyone can have confidence and assurance in terms of the integrity of our food safety system."