Raw milk now has to carry labels warning buyers of the risks.

"I wouldn't drink raw milk and I wouldn't give it to my family," says a leading food safety scientist.



Massey University Professor Nigel French said it was "almost impossible" to produce raw milk that was free of bacteria from cow faeces.



"Although tests are being done and many times they pass the test, that doesn't guarantee the milk is free from harmful bacteria," said French. "The tests aren't highly sensitive. It's still possible you would have bacteria in the milk."



This week Manawatu raw milk supplier Arran Farm recalled batches of raw milk and closed for a week over fears its milk contained campylobacter, a key food poisoning bacteria.



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In January, Southland raw milk suppliers Go Farming Limited recalled batches of its Go 2 Raw Milk brand because of campylobacter fears and the same company had a recall in September last year over fears of listeria contamination.

Also in September last year, Wanaka Milk Company recalled batches of its Udderly Fresh Raw Milk over campylobacter fears.

TOM LEE/STUFF The milking shed is not a sterile place.

French, who is director of the New Zealand Food Safety Science and Research Centre, said unless cows were invented that didn't produce faeces, milk would continue to be contaminated.

"The milking shed is not a sterile place. Even with the best udder preparation and best practices, you still can't guarantee that milk will be free from bacteria from the faeces of the cows producing it."

Raw milk is milk that hasn't been heat treated (pasteurised). In New Zealand, that means heating the milk to around 74 degrees Celsius for about 15 seconds. This kills harmful bacteria such as campylobacter, listeria, and toxin-producing strains of e.coli.

NZFSSRC Professor Nigel French says it's easy to make raw milk safe with a little heat.

Raw milk advocates claim that raw milk is healthier than pasteurised milk in a variety of ways.

But a 2015 Review of the Health Benefits of Raw Milk Consumption by the Prime Minister's Chief Science Advisor Dr Peter Gluckman concluded: "The claimed health benefits of raw milk compared with pasteurised milk are for the most part not backed by scientific evidence, making the risk-benefit ratio very high for this food product, particularly among the vulnerable groups."

High risk groups are pregnant women, children and babies, elderly and people with weak immune systems.

WARWICK SMITH/STUFF Arran Farm at Feilding is the latest raw milker seller to recall batches because of a contamination scare.

In November 2016, selling raw milk came under new, tighter regulations.

They included that raw milk could only be bought from farmers registered by the Ministry for Primary Industries. Raw milk sellers had to be verified, test the milk for pathogens, keep sales records and have labelling that included use-by dates, storage advice and warnings about the risks of raw milk for high-risk groups.

Farmers could only sell raw milk directly from the farm gate or by delivering to a home. So no collection points, such as at the nearby health shop.

Also buyers needed to supply contact details so they could be reached if a batch of milk failed bacteria testing.

French said the bacteria he particularly feared was the shiga-toxin producing e.coli.

"There have been some really terrible cases of children dying and getting permanent kidney damage as a result of drinking raw milk that contains some of those pathogens."

He said that New Zealand had one of the highest incidences in the world of that particular disease.

"We know it's very strongly associated with people living in rural areas where there are a lot of cattle. We have a pretty good idea that it came into New Zealand around about 1970-1990. The first human case was in New Zealand in 1993, and since then the incidences have increased steadily year on year.

"That's the one that really concerns me. If raw milk with that in it was given to a child, the consequences could be really, really serious."

French said pasteurisation was introduced in the first place to protect the public against these kind of bacteria.

Selling raw milk is banned in Australia.