The Ministry for Primary Industries is reviewing the regulations governing the sale of raw milk.
The Village Milk company has suspended the operation of its Timaru franchise after people became sick with campylobacter through drinking the unpasteurised milk sold early in March. Public health officials say dozens of people could yet fall ill.
However, the company says inconsistent test results indicate the source of the campylobacter may not be in the milk at all but from another source outside the farmers' control.
The ministry is investigating and says in the meantime it's having a look at regulations surrounding raw milk sales.
It says al product leaving farms has to be safe and fit for purpose, and farmers need to maintain standards surrounding animal health and husbandry, farm dairy design, hygiene and food safety.
But it says those rules are not as robust as those governing food sold to the public elsewhere, so it is reviewing the regulations, as raw milk gains in popularity.
A ministry spokesperson, Gary Orr, says new research is being looked at, and the ministry plans to consult with the public on developing any new options should they be required.
Heat it first, advises doctor
There are seven confirmed cases of campylobacter but the South Canterbury Medical Officer of Health, Daniel Williams, says that's only the people who went to their GP and they're usually the tip of the iceberg in a situation like this, because raw milk is an effective conduit for bugs.
"We have in the past had outbreaks of other bacteria," Dr Williams says. " We've had cases of e.coli which were also linked to drinking raw milk. Raw milk can be contaminated with any of the bugs that live in the cow's gut."
Dr Williams says people should heat the milk to 70degC for a minute if they really want to drink it raw, as that will kill most of the bug.
"Essentially, it is a high-risk product and drinking it without treating it with heat is a dangerous thing to do."
No need to heat it, says company
Village Milk chief executive Mark Houston disagrees with heating the milk, saying it ruins the nutritional value, and insists that properly handled raw milk is a safe product.
"Generally milk comes out of the cow's udder with absolutely no bugs in it," he says. "It's absolutely pristine at that stage, and it's only contamination that happens after that that is a problem with health for people.
"We've been selling milk for nearly three years and we've sold 330,000 litres - no cases of illness whatsoever. In effect, we've probably had hundreds of cases of people's health improving."
In the meantime, Village Milk's raw milk operation remains closed.