Members may have heard or viewed various reports in the media in recent weeks about the issue of residual methamphetamine in rental accommodation. This communication is intended as a summary of some key points that have emerged from the ongoing debate about the subject:
The often quoted maximum acceptable level of surface contamination of 0.5 micrograms of methamphetamine per 100 cm2 of surface area (e.g. wall surface) is based on the ‘Guidelines for the Remediation of Clandestine Methamphetamine Laboratory Sites’ published by the NZ Ministry of Health in 2010.
The guidelines have been developed using a pragmatic approach to the safe remediation of non-workplace sites that have been used in the illicit manufacture of methamphetamine.
The clandestine (illegal) manufacture of methamphetamine involves ‘cooking’ a range of toxic chemicals to produce the illicit drug.
Most of the chemicals used to manufacture methamphetamine are toxic in their own right. The illicit manufacturing process may also cause surface contamination of floors, walls, ceilings, and furnishings etc. These other residual chemicals may include iodine, lead and mercury. Other toxic chemicals used or emitted in the manufacturing process may include benzene, hydrogen chloride, phosphine, toluene and xylene’s. These latter chemicals are described as volatiles (i.e. they change from liquids to gases at room temperature) and would not be present as surface residues (or dust) for a sufficient period after manufacture to be of concern.1
The ‘0.5’ maximum acceptable level of methamphetamine is intended to be used as an indicator only. That is to say, if a property that has been used for ‘clan lab’ purposes has been remediated and cleaned, the ‘0.5’ methamphetamine level is considered to be an indicative ‘safe’ residual level for not only the methamphetamine produced but also for the chemicals that may have been used in the ‘clan lab’ activity.
It is important to note is that the guidelines are intended to be applied only to those circumstances where the clandestine (illegal) manufacture of methamphetamine has occurred.
It is becoming clear the Ministry of Health guidelines, and the ubiquitous ‘0.5’ level are not intended to be applied to circumstances where ‘meth’ may have been ‘smoked’ that is, consumed for personal use.
It has been reported in the media that residual methamphetamine is common in our environment at low levels, that is at around the ‘0.5’. An example cited on TVNZ's Fair Go programme recently was the presence of residual ‘meth’ on bank notes in general circulation.
It has also been reported in the media that two cases taken by Housing New Zealand (HNZ) to the Tenancy Tribunal seeking to claim the costs of remediation from residual meth contamination against the tenants have failed.
In one case, a level of meth, just above the guideline, was detected on an extractor fan in a house. Housing New Zealand evicted the tenant and claimed expenses of $10,000 from the tenants for the clean-up in which doors were removed as well as an oven, extractor fan, and light fittings. In July this year the tribunal ruled the decontamination work bore no resemblance to the contamination. "This quote and outline of work has obviously been accepted at face value by HNZ without further enquiry or analysis," the tribunal ruled.
In another case, ruled on in May, Housing New Zealand tried to evict a tenant for meth contamination, again after low levels of meth were detected. In this case the tenant disputed the allegation and accused Housing New Zealand of breaching health and safety legislation by renting them an uninhabitable house. Housing New Zealand had to refund several months’ rent to the man it had accused. The Tenancy Tribunal decision found there was no way of determining when the contamination occurred.
Senior HNZ officers and the Minister responsible for Housing New Zealand, Bill English, are on record as saying the Corporation is operating to a Ministry of Health guideline which is regarded “as not quite appropriate for dealing with use of P in houses.” 
Minister Bill English has also been quoted in the media as saying that Ministry of Health will begin consulting on new guidelines in October.2
Massey University environmental chemistry lecturer Dr Nick Kim, and one of the contributors to the development of the 2010 MOH guideline, has said that removing tenants and decontaminating a house was overkill in cases where the drug had been used, rather than manufactured. In a recent scientific paper Drake estimated the lowest level of surface contamination from methamphetamine at which adverse health effects could begin to become remotely plausible was, in his opinion, about 12 micrograms per 100cm2. This is about 24 times higher than the remediation guideline of 0.5.
So what does all this mean for residential rental property owners? My take on these matters goes like this:
This communication has been prepared for members’ information and does not necessarily represent the views or policy of the New Zealand Property Investors’ Federation by Colin Comber, Secretary of the NZPIF.
 Ministry of Health. 2010. Guidelines for the Remediation of Clandestine Methamphetamine Laboratory Sites. Wellington: Ministry of Health.
 Radio New Zealand - National
 Methamphetamine residues on surfaces – potential for (real) health effects. Dr N Kim, College of Health, Massey University, Wellington - June 2016.
 Residential Tenancies Act 2010 s51 (1) (c)