Understanding methamphetamine contamination

What contamination is

Methamphetamine, often called meth or ice, is a synthetic stimulant. When it is smoked or manufactured indoors, chemical residue settles on surfaces throughout the building. That residue can remain on walls, ceilings, carpets and fittings for months or years after the people responsible have left.

Contamination is measured as the mass of methamphetamine found on a defined area of surface. Australian reports use micrograms per 100 square centimetres (µg/100 cm²). One microgram is one millionth of a gram, so the amounts are tiny, but people living in a property are in contact with those surfaces every day.

Smoking versus manufacture

There are two very different ways a property becomes contaminated, and they carry different levels of risk.

Contamination from smoking

This is by far the most common source in Australia. Each time meth is smoked, vapour drifts through the room and condenses on cooler surfaces. Repeated use over months builds up a layer of residue. Results can range from just above the guideline to many times higher in rooms used heavily.

Contamination from manufacture

Clandestine drug laboratories, often called clan labs, use solvents, acids, corrosives and precursor chemicals as well as producing the drug itself. Former lab sites can have very high meth levels plus other hazardous chemicals in walls, plumbing, soil and septic systems. Rental properties are the most common locations, but commercial and industrial sites, remote rural properties, hotels and motels are also used. Former labs need a more detailed assessment under the national clandestine laboratory guidelines.

Where residue collects

Residue moves with air and hands, so it tends to concentrate in predictable places. Testers use this knowledge to decide where to sample.

• Ceilings and upper walls, where warm vapour rises and settles.
• Light switches, power points and door handles, which are touched often and rarely cleaned. NAMC is currently researching whether switches and power points hold higher levels than nearby walls.
• Air conditioning ducts, exhaust fans and range hoods, which draw contaminated air through the building.
• Carpets, curtains and soft furnishings, which absorb residue and are often too contaminated to clean.
• Porous materials such as unsealed timber, plasterboard and grout, where residue can soak in below the surface.

Health effects

Exposure to residue left in a home is sometimes called third hand exposure. Until recently there was very little data on what it does to people. A study led by Dr Jackie Wright collected information from 63 people across 25 case studies who had unknowingly lived in contaminated properties. Their health was assessed alongside environmental testing results and hair analysis that confirmed exposure.

The study identified a consistent range of effects reported by residents:

Symptoms are not unique to meth exposure and can have many causes. If anyone in your household is unwell, see your GP and tell them about your concern so they can consider it. Many people report that symptoms ease after they leave the property or after it is remediated.

Who is most at risk

Exposure happens mainly through skin contact with surfaces and then hand to mouth contact, with some exposure through breathing in dust. That means the people who spend the most time close to surfaces are the most exposed.

• Babies and toddlers crawl on floors, touch everything and put their hands and toys in their mouths. They also weigh less, so the same amount of residue is a bigger dose.
• Pregnant people should avoid unnecessary exposure.
• People with existing respiratory or skin conditions may notice symptoms sooner.
• Workers such as cleaners, tradespeople and property inspectors who enter contaminated properties regularly without protection.

Guideline levels explained

A guideline level is the amount of residue below which a property is considered suitable to live in. Australian guidelines apply 0.5 µg/100 cm² for residential properties. The level is deliberately conservative, designed to protect a young child living full time in the home.

Different documents and states have published different values over time, and some apply other levels for commercial settings or for surfaces that people rarely touch. Your tester should state clearly in the report which level they applied and the guideline it comes from. You can read the source documents in our guidelines library.

Warning signs worth taking seriously

None of these prove contamination, but each is a reason to test before moving in or reletting.

• A history of police activity, raids or arrests at the address.
• Unexplained yellow or brown staining on walls, ceilings or around exhaust fans.
• Smoke detectors removed, disabled or covered.
• Windows blacked out or covered, and unusual ventilation or extra locks.
• Chemical odours, stained sinks or burn marks, which may point to manufacture.
• Household members developing symptoms soon after moving in.

Myths and facts