P use is affecting children in every classroom in Northland: Principal

P use is likely harming children in every classroom in Northland, a leading principal says.

Te Tai Tokerau Principals Association president Pat Newman says rampant use of methamphetamine in the north was affecting so many families it had become a major concern at schools.

"I would doubt there is a class in Northland that doesn't have a child that is somehow affected through P," he told Newstalk ZB's Early Edition today.

"That could be, at the very worst, living in a house where it is manufactured and breathing in the fumes, through to parents using the money for [drugs] that should be on food, to seeing violence that goes with P."

"The authorities will tell you it is probably easier to get your hands on P than it is on marijuana in the north."

The prevalence of P has also been highlighted in a report published this week in the Royal Society of New Zealand's social sciences journal.

It looked at 578 children affected by their parents' drug use and found substance abuse was the number one cause for some children living with their grandparents.

Such children only had "often sporadic and unsatisfactory" with their parents, many of whom had died, gone to prison or moved away.

And 14 per cent of grandparents said one or more of the children in their care had assaulted them physically.

"In most cases, the child appeared to lose control of their responses," the report said.

Newman said that as more children came to school affected by P, teachers were finding students exhibiting "all sorts of behaviours".

"Usually it is delayed developmental, so your 5-year-old is not ready to go into a classroom," he said.

He said Northland schools and agencies were used to "getting very little help" to combat drug use and ultimately the community needed to take responsibility for the issue, including by reporting P use so agencies could tackle the problem.

"We've had children removed from homes because of the P use in the home and I think it's the community that needs to say, 'look, we own this problem'," Newman said.

"It is too big for schools to do it on their own, it's too big for agencies to do it on their own, it has to be the community that turns around and says enough is enough."