Dr Leo Schep

Housing New Zealand is spending millions of dollars cleaning up traces of methamphetamine that a poisons expert says pose ‘‘minimal risks of toxicity'' unless the house was used to manufacture the drug.

The corporation has spent $5.8 million cleaning up methamphetamine contamination in the past six months, a spokesman confirmed yesterday.

None of the eight state houses in Otago-Southland that tested positive for methamphetamine contamination in the past 18 months was used to make the drug.

The spokesman was unable to say how many of the 508 houses identified nationally as needing decontamination had been used for manufacturing, but a ‘‘very significant majority'' involved consumption only.

National Poisons Centre toxicologist Dr Leo Schep, of Dunedin, said dealing with a house where someone had smoked methamphetamine was quite different from dealing with a former laboratory.

‘‘People living in a laboratory environment risk suffering adverse cardiovascular, respiratory and dermal effects following the exposure to organic solvents, acids, alkalis and other chemicals.

‘‘However, people dwelling in a house where previous tenants had smoked methamphetamine, and there is some evidence of low concentrations on surfaces, have minimal risks of toxicity.‘‘

The risks would be similar for people who live in a house that had previous dwellers who smoked cigarettes or marijuana.

‘‘They will have exposure to these drugs but the concentrations will not be sufficiently high enough to cause either psychoactive or toxic effects to people who may have had inadvertent, and brief, dermal contact with these surfaces,'' Dr Schep said.

Dr Schep made his comments in a Science Media Centre media briefing, and declined to elaborate when contacted.

In a statement, HNZ chief operating officer Paul Commons said the corporation's policy was to not knowingly permit tenants to live in a property that registered readings above Ministry of Health contamination guidelines.

‘‘This supports our commitment to providing a healthy environment for our tenants.‘‘

Over the last few years, Housing New Zealand has placed greater focus on identifying homes where [methamphetamine] may be used, or may have been used in the past, rather than manufactured.

‘‘Where we suspect one of our properties may be contaminated with methamphetamine, the property will always be tested and remediated as necessary,'' Mr Commons said.

eileen.goodwin@odt.co.nz