New Zealand state homes are increasingly being treated after P use.

As many as 600 state homes will need P decontamination this year, amid claims retirees are now smoking the toxic drug.

The Housing New Zealand figures, released under the Official Information Act, show the number of state homes decontaminated for methamphetamine, also known as P, has skyrocketed in the past two years.

Two years ago 28 state homes had to be decontaminated but in the first quarter of this financial year alone 174 homes were decontaminated.

Supplied This Auckland house looks like any suburban home but Housing NZ had to spend $15,5000 on P remediation work that involved stripping wall linings.

During the past three financial years, 13 state homes had to be demolished P contamination.

Housing New Zealand chief executive Glen Sowry said he was "extremely concerned" about the growing problem. It was almost certain tenants were living in contaminated state homes.

"This is a significant and growing issue for all landlords. We are the biggest landlord in the country so we are certainly not immune to it."

Supplied This Housing NZ home, where children clearly lived, had to have $18,600 work done on it after it was contaminated by P.

However, the rise could be attributed to greater detection, through co-operation with police, rather than more drug abuse in state homes, he said.

If unsafe levels were found, tenants were moved out immediately.

Photos of contaminated houses provided by the agency show homes that need decontamination had their walls and floor lining stripped.

Supplied A paddling pool and a meth house.

At one home, children's toys were piled up and a paddling pool and ride-on toys were in the garden.

"It's not like you walk in and it's covered in paraphernalia or a mini Breaking Bad lab," Sowry said.

Each home needing decontamination cost between $8000 and $16,000, with the work costing the agency $2.3 million last year.

Detective Sergeant George Campbell, from the Wellington Police clandestine laboratory team, said while there were probably less labs now, those remaining were bigger, mobile and more organised.

"People are getting a bit more crafty, as opposed to what they were 10 years ago."

Police had busted some large labs, such as a lab in Whangarei in December believed to be capable of producing $3 million of P in a week.

"The demand for methamphetamine in New Zealand is still huge."

Drug Detection Agency chief executive Kirk Hardy said the percentage of positive tests for amphetamine-based drugs, including P, was on the rise.

"From people using it as teens to people using it in retirement age."

He knew of children as young as 10 who tested positive for P as a result of living in P homes.

Social Housing Minister Paula Bennett said every house that needed decontaminating was a place vulnerable people could have been using.

"We will not tolerate meth use in our social housing. We are not going to risk houses suspected of being drug dens today, becoming potentially toxic playgrounds for innocent children in the future."

Housing NZ was working with police to focus more on eliminating P use in homes "as opposed to previously only targeting home-based drug manufacturing in the homes", she said.

Detective Senior Sergeant John Brunton, from the clandestine laboratory response team, said when P was detected in homes it was hard to say if the contamination came from P use - which had less detrimental health effects - or labs.

"It's a nasty drug that ruins lives."

P CONTAMINATED HOMES UNHEALTHY

* P can cause neurological damage, irritation, and kidney failure, particularly among small children crawling in contaminated carpet.

* In addition, inhaling or ingesting chemicals used in the drug's production. can be dangerous. Concentrated corrosive acids could cause injuries while volatile hydrocarbons like benzene could cause cancer and kidney damage.

* Heavy metals sometimes used in production, like mercury and lead could also cause neurological or kidney damage, and birth defects, presenting a particular risk for pregnant women.

WHAT IS P?

* P, or pure methamphetamine, is a central nervous system stimulant made from pseudoephedrine.

* It stimulates the brain to release the "pleasure" chemical dopamine. A normal "high" without drugs releases 100 units and a cocaine buzz about 400 units. P releases about 1250.

* It creates euphoria or sense of invincibility that can last for up to 12 hours, but can cause paranoia, sleeplessness for days, agitation and hallucinations.