Primary schoolteachers say they are increasingly being kicked, punched and stabbed by disturbed children suffering the effects of their families' drug use and poverty.
NZ Principals' Federation president Whetu Cormick said he was getting increasing reports of "severe behaviours" involving children who in some cases were disturbed from birth because their mothers used methamphetamine ('P') when they were pregnant.
"We are hearing from some colleagues that they have such children in their schools, and it is of concern," he said.
"It's not widespread. I haven't heard of this in the South Island, but it's in several parts of the North Island. Increasingly it's becoming an issue."
Cormick said he raised the issue in recent meetings with both Education Minister Hekia Parata and the Secretary of Education, Iona Holsted.
"I talked about colleagues being physically attacked, kicked in the private parts, punched, poked in the eye - actually stabbed in the eye with a pencil," he said.
The teacher who was stabbed in the eye "needed medical treatment" but did not lose sight.
He said children affected by parental meth use did not respond to teachers' usual strategies.
"There is no behaviour modification management you can put in place. Giving stickers or sweets won't work. There's nothing you can do," he said.
"I remember a good friend in Northland said to me there's nothing you can do but rub their backs. There is no way to console all those children other than to rub their backs."
He was speaking after Te Tai Tokerau Principals' Association president Pat Newman said meth use had been endemic in Northland for more than five years and primary schools were now seeing the inevitable outcome.
"P babies are now in primary schools," he said.
A world-leading researcher on the effects of prenatal methamphetamine use on children, Auckland University Associate Professor Trecia Wouldes, said a study she did with Northland midwives also pointed to endemic meth use in the region.
"I was asking them, when they booked their antenatal checks, whether they asked them [pregnant women] whether they were using drugs. She said, 'Absolutely, because everybody is,'" Wouldes said.
"Here in Auckland a lot of them said they didn't ask the questions. The Northland midwives were quite open about doing a check."
However her major study, which has followed 107 children whose mothers used meth in pregnancy since 2006, has found that brain damage caused by using meth during pregnancy may not be irreversible in the way it is with alcohol.
"I've had mums in our study who used meth in their pregnancy, and when they realised they were pregnant they quit and haven't gone back to it. The child is fine," she said.
"It takes more than being exposed prenatally to meth to make you violent. It takes not just exposure to the drug, it takes modelling domestic violence in the home because you have a father maybe who is violent, and maybe being exposed to a mother who is mentally unwell and still using drugs."
She said many of the mothers who used meth were also drinking alcohol "in large amounts", and 67 per cent of the mothers were also diagnosed with mental illnesses.
The combined effect of all these factors was to weaken the children's "executive function" - the ability to control their own behaviour.
"It means that you probably struggle to sit quietly and attend to something, and if you can't attend to something you can't learn," she said.
"Shifting from one task to another task is executive function as well. So if the teacher says, 'Okay, we've been reading, now we're going to do maths,' some kids don't want to shift, they want to carry on reading."
NZ Drug Foundation director Ross Bell said meth use was just part of a much bigger problem lying behind the increase in disturbed children.
"For us the problems are more around poverty, despair and isolation," he said.
"You have entrenched poverty, you have entrenched unemployment, and high levels of cannabis use and methamphetamine use. I think these are bigger social and economic factors that are driving the problems that Pat [Newman] is having to deal with."