"It blistered and burned her lips and the inside of her stomach. I knew the child. It took months and months treating her serious burns and having surgery."
Thorburn, now a drug and alcohol educator, says P-making chemicals are often stored in food and drink containers and around food - something brought home graphically in police photos supplied to the Herald on Sunday.
One shows an immaculate pantry, shelves stacked with supermarket-brand food, children's paracetamol, baby formula and a container of hypophosphorous acid, used to turn ephedrine to methamphetamine.
Other photos show drug gear stored in children's lunch boxes, fizzy drink bottles and in a suitcase under a 12-year-old's bed.
For lawyer Chloe Barker, who wrote her Masters of Science in Forensics thesis on the topic of children in P labs, the photos were shocking and heartbreaking.
"I didn't realise the extent to which those children were suffering," she said. The long-term physical damage from chemicals was not yet known, but the psychological damage was undeniable.
"We need to do something about it. The P lab for children poses so many different risks and unless you actually have legislation that addresses all of the direct and indirect harms that children are exposed to in the lab, then we're not really doing the children justice."
Police prosecute P users and makers for the drug-related activities, meaning a parent who is not involved in the drugs may not face any consequences for allowing their children to live in that environment.
Barker found evidence that many parents are aware, yet naive about the dangers. Some shut children in their rooms to protect them while they make P, not realising the children's bedrooms became contaminated anyway.
Hair swabs from many children (21 from 2008 and 2009) contained the methamphetamine levels of an adult; a 4-year-old could describe the methamphetamine "cooking" process and a 9-year-old acted as a methamphetamine drug runner.
Police try to avoid busts when children are home and ask CYF to be present. Any children found at a P lab are changed into protective suits then taken to a police station or CYF facility for a shower rather than being decontaminated with the high-powered showers used on adults. Police also swab areas and objects in the home where children can reach, and gather their clothing and toys for evidence of contamination.
But what happens to the children after that? Barker found examples of parents being released on bail, going home and cooking again - with their children in the house.
Social Development Minister Paula Bennett declined to comment this week but, in April, responding to questions from Labour's Jacinda Ardern, Bennett said the ministry did not collate data on the number of notifications received from police of children living in homes with P labs.
CYF general operations manager Kelly Anderson said the department was "actively working" on a joint protocol with police for children in such homes. They worked with police to assess children's safety and make care arrangement when necessary. If police found children in a P lab they could exercise emergency powers to place them in CYF care.
Anderson said: "Any decision to return a child home will be carefully considered and must be in their best interests."
Police national clandestine lab response team manager Detective Senior Sergeant John Brunton said the police methamphetamine control strategy had been in place since November 2009, but discussions with CYF were still ongoing.
Labour's Ardern said a CYF protocol was urgently needed: "Just because those children may not have been abused in the strictest sense of the word, they've certainly been exposed to an environment that's just not acceptable."
Thorburn, who is now married and has a 17-month-old daughter and another on the way, said addict parents lost sight of everything but the drug.
His partner during his $3,000-a-day drug-using days continued smoking P while pregnant and miscarried. She also made P while her 10-year-old so was in the house.
• For help kicking a habit, call the alcohol and drug helpline: 0800 787 797
• To report on a child at risk from exposure to methamphetamine phone police or crimestoppers: 0800 555 111
