There's no evidence methamphetamine residue on household surfaces resulting from smoking impacts health, a new Government report has found.
That means Housing New Zealand may have pointlessly emptied several hundred state houses and wasted a good chunk of $100m on cleaning houses in which meth was smoked but not manufactured.
As a result of the report, 240 state homes with low levels of meth will be released within weeks for people to live in.
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The Drug Foundation's Ross Bell is calling meth testing the "biggest scam New Zealand has ever seen".
But while there's "no evidence" residue left by typical meth smoking can impact health, houses where meth manufacture has been taking place involve "additional risks". That's because additional contaminants may be present in a meth lab. The report found a former meth lab with low levels of methamphetamine is likely to have low levels of other substances.
Housing New Zealand (HNZ) will now use a new standard of 15 micrograms of meth detected per 100 square centimetres after cleaning, expecting to save $30m a year in remediation and testing. That's 10 times the current limit of 1.5 micrograms. It used to be 0.5 micrograms after cleaning.
Moral panic around meth has seen houses emptied, the report's author, the Prime Minister's Chief Science Advisor Sir Peter Gluckman, said.
The health risk of living in a house where meth has been smoked is so low, Sir Peter said, that he "can't see the point of testing, full stop".
He said he would be comfortable with a toddler crawling around licking surfaces where 100 micrograms were present.
Groups like the New Zealand Drug Foundation have long been warning meth tests are overzealous, and the previous guidelines were designed for houses with labs, not where meth has only been smoked.
The report found the level of meth found in New Zealand's properties that do test positive is low.
Of 1600 tests carried out, 1 percent had levels above 30 micrograms, which would indicate a meth lab.
"There has been some anxiety about meth contamination, and a testing and remediation industry has grown up around this," Mr Twyford said on Tuesday morning.
New Zealand's "biggest scam" - Ross Bell
Ross Bell from the New Zealand Drug Foundation says New Zealanders should be outraged.
"This has been the biggest scam New Zealand has ever seen," he told Newshub.
"In terms of the scale of costs, Government's social housing provider Housing New Zealand has spent $100 million on this, [and] the scale of the social harm on those families who have been evicted as a result of a cowboy industry."
Mr Bell said the previous Government had been warned meth contamination fears were overblown, but "chose to take no action."
That's refuted by National's social services spokesperson Paula Bennett, who told Newshub she and former Prime Minister Bill English were asking Housing NZ "a whole lot of questions" about the testing.
"To be honest, I fought back pretty hard and was at time told it was inappropriate to be trying to direct Housing NZ as a Crown Agency [that] as a consequence have to work independently," Ms Bennett told Newshub.
"I'm pleased with today's result. There's no way we wanted empty houses that didn't have to be empty."
Ms Bennett said at the time, Housing NZ were increasingly concerned about the dangers of meth and the agency decided to "put health and safety first and veer on the side of the conservative."
A test costs anywhere between $500 and $5000, and cleaning of a house that tests positive can cost anything between $2000 and $50,000.