31 May 2018
Note: more recent information is available in Sir Peter Gluckman’s publication Methamphetamine contamination in residential properties: Exposures, risk levels, and interpretation of standards (PDF, 532 KB).
A Ministry of Health funded report provides key recommendations for the country's first national standard for methamphetamine contamination.
The report, prepared by ESR, recommends that a different level be used to guide clean up where meth has been used, compared to the level for houses where the drug has been manufactured.
The report recommends that the current contamination level that prompts a clean-up stays the same for houses where the drug has been manufactured but is four times higher for houses where the drug has only been used and where there isn’t any carpet. The level is three times higher for houses where only drug use is found, but where there is still carpet in the house.
The report notes that drug residue on carpets is more likely to result in chronic exposure to contamination for babies or toddlers who spend more time in contact with the floor.
The different levels reflect the level of health risk from living in a house where someone smoked methamphetamine, and living in a house used to manufacture the drug.
Living in a methamphetamine laboratory environment means potential exposure to chemicals at sufficient level to be linked to adverse cardiovascular, respiratory and dermal effects from exposure to methamphetamine, organic solvents, acids, alkalis and other chemicals.
But people living in a house where previous occupants had only smoked methamphetamine means potential exposure to low concentrations of the drug on surfaces with a much reduced risk of toxicity.
The recommendations for houses with carpets in which there has only been drug use follow those used in California, and which are increasingly being adopted by other US states.
Based on the recommendations now provided, the Ministry of Health believes houses which don't trigger the clean-up levels for methamphetamine are as safe to occupy as any other similar house.
The Ministry of Health believes the new recommendations will help guide clean-up efforts based on an appropriate assessment of risk. The recommendations will now be considered by the committee appointed by Standards NZ to develop the new standard.
In the absence of a guideline for remediating property contaminated by methamphetamine use but not manufacture, these recommendations can be used in the interim. But the recommendations will not preempt the standard which is currently being developed.
While the Ministry's recommendations are being considered by the Standards Committee, its recommendations are available on the Ministry of Health website.
The new NZ Standard, once developed, will supersede the Ministry's existing Guidelines.
The Ministry of Health, which is also on the NZ Standards Committee considering the issue, will be working with agencies involved to look at how promote information about the new standard when its developed.
The recommended levels identified in the report are:
- 0.5 µg/100cm2 for houses where the drug has been manufactured (unchanged)
- 1.5 µg/100cm2 for houses where the drug has only been used – carpeted
- 2.0 µg/100cm2 for houses where the drug has only been used - uncarpeted
Several agencies have roles related to the remediation of methamphetamine contaminated buildings. The lead agency (regulator) for dealing with methamphetamine contaminated buildings is the local council. Councils can take action using their powers under the Building Act 2004 or the Health Act 1956. These actions may include:
- recording the contamination on the property’s Project Information Memorandum (PIM) or Land Information Memorandum (LIM)
- requiring the building owner to clean and/or close the building
- requiring the building owner to re-test the building
- requiring the building owner to demolish the building.
While not the regulator, the Ministry of Health developed guidelines for the remediation of clandestine methamphetamine labs. These guidelines are now over six years old.
In 2015 Standards NZ (MBIE) began work to develop a new standard for dealing with methamphetamine contaminated buildings.
In 2016, the Ministry of Health contracted ESR to undertake an independent review of the current guidelines to provide updated advice on the values for remediating methamphetamine contaminated buildings. The scope included seeking advice on both remediation of properties used as clandestine labs and solely for recreational use.
The ESR report has now been received by the Ministry and the recommendations form the advice the Ministry is presenting to Standards NZ Committee which is working on the development of the new meth standards.
The analysis includes a review of evidence and comparison of the risk assessment approaches used in New Zealand, Australia, Colorado and particularly California (which is based on a comprehensive review of the toxicological literature, using human data, and noted as the preferred comparison value for a safe daily exposure).
The ESR report also recommends an extra test for the presence of lead and mercury as part of the clean-up of clandestine labs.