Report on health effects of methamphetamine residue in residential properties

The Prime Minister’s Chief Science Advisor Professor Sir Peter Gluckman has released a report on the health effects of methamphetamine residue in residential properties - Methamphetamine contamination in residential properties: Exposures, risk levels, and interpretation of standards (the CSA report).

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Report on methamphetamine contamination - questions and answers

Why was the report commissioned from the Prime Minister’s Chief Science Adviser?

The Government asked Professor Sir Peter Gluckman – the Prime Minister’s Chief Science Advisor - to assess all the available scientific evidence and medical literature about the risks of exposure to methamphetamine residue in houses. The assessment examined the likelihood of health risks from methamphetamine residue caused by smoking compared with that caused by manufacture.

 The CSA report was commissioned in the context of the Residential Tenancies Amendment Bill (No 2), currently before Parliament, which includes provisions to address contamination in rental properties, including contamination from methamphetamine.

What is the purpose of the CSA report?

The purpose of the CSA report is to provide a comprehensive, up-to-date and plain English understanding about the risks of methamphetamine exposure for people living in houses where methamphetamine was manufactured, and for those where it was smoked.

Along with New Zealand Standard (NZS) 8510, Testing and decontamination of methamphetamine-contaminated properties (NZS 8510:2017), the CSA report will be a matter to be considered when developing regulations under the Residential Tenancies Act, as amended by the Residential Tenancies Amendment Bill (No. 2). The Bill is shortly to have its Second Reading in Parliament.

What did the CSA report cover?

The report looked at the science related to methamphetamine as a contaminant, including the rationale for remediation and the history of guidance in New Zealand and elsewhere for methamphetamine clean-up levels, the evidence of health risks from living in a house where methamphetamine was previously smoked and those from living in a house where it was manufactured, toxicity assessments, and how risk-based guidance on remediating methamphetamine residue in houses should be established.

The report considered relevant peer-reviewed scientific literature from New Zealand and internationally, as well as reports published by respected scientific bodies, such as national academies and Crown Research Institutes and was accompanied by multiple interviews with experts and stakeholders both in New Zealand, Australia and the USA. It was peer reviewed by New Zealand and international experts.

What are the findings and recommendations?

  • Dwellings can become contaminated with methamphetamine residues if the drug is manufactured or smoked within it. Manufacture of methamphetamine in general results in greater methamphetamine residue levels than levels caused by smoking alone.
  • There is currently no evidence that levels typically resulting from third-hand exposure to methamphetamine smoking residues on household surfaces can elicit an adverse health effect.
  • Methamphetamine levels that exceed the NZS 8510: 2017 clean-up standard of 1.5 µg/100 cm2 (micrograms per one hundred centimetres squared) should not be regarded as signalling a health risk.
  • Exposure to methamphetamine levels below 15 µg/100 cm2 would be unlikely to give rise to any adverse effects. This level still incorporates a 30-fold safety buffer on a conservative estimate of risk.
  • It is important that guidance for mitigation measures are proportionate to the risk posed, and that remediation strategies should be informed by a risk-based approach.
  • Because the risk of methamphetamine residue at levels that might cause harm is extremely low, testing is not warranted in most cases. Testing is only recommended where meth lab activity is suspected or where very heavy use is suspected.
  • Combining multiple samples taken throughout a dwelling into a single composite sample, as permitted in NZS 8510: 2017, has limited value and cannot accurately reflect levels of risk, and in fact can lead to false impressions of high exposure.
  • Remediation according to the NZS 8510: 2017 standard is appropriate only for identified former meth labs and properties where excessive methamphetamine use has been determined. This would only be as a precautionary measure to remove other toxicants that may be present but not measured.

What actions should landlords and tenants take now where methamphetamine is discovered in a rental property?

Tenants and landlords must continue to meet their obligations under the RTA. Using, possessing and manufacturing methamphetamine are offences under the Misuse of Drugs Act 1975. Tenants who are found to have smoked or manufactured meth in a rental property are in breach of the RTA for using the rental premises for an unlawful purpose. Tenants who cause methamphetamine contamination of rental properties are in breach of their obligation not to intentionally or carelessly damage the rental premises.

Landlords who provide premises which are methamphetamine-contaminated are in breach of their obligation to provide habitable premises which are in a reasonable state of cleanliness.

Where there is a dispute about contamination, landlords and tenants can apply to the Tenancy Tribunal to adjudicate on the matter. The Tribunal will take into account all evidence put before it and make a binding decision.