Well-off Kiwis living in cities are more likely to binge on cocaine and ecstasy at the weekends than people living in poor and rural areas, a new study has found.
In contrast, small-town drug users prefer using methamphetamine, indulging every day.
Researchers from the University of Auckland, Massey University and the University of Queensland tested wastewater at various spots in Auckland, the Bay of Plenty and Canterbury over a week in 2018, timed to coincide with that year's census.
"This provided a way to quantify drug use and sociodemographics and assess the accuracy of drug survey techniques," their study, published in the New Zealand Medical Journal on Friday, said.
They found methamphetamine present in every sample they took, averaging out to one dose a day for every 44 people (22.9 doses a day per 1000 people). Usage was highest in towns and rural areas, and mostly consistent throughout the week.
Ecstasy (MDMA) was significantly less common - about one in 588 people using it each day - and cocaine even rarer, just one in 2000.
"Methamphetamine consumption (and to a lesser extent MDMA) was high compared to that reported for Western nations, while cocaine consumption was extremely low," the study said.
"Cocaine and MDMA consumption were higher in cities compared to towns."
They also spiked in popularity at weekends - about between 71 and 247 percent - backing up a 2017 study based on data collected in 2014, which had a similar conclusion. Meth use was consistent in most places, likely because of how addictive it is - though there was a spike at weekends near the Port of Tauranga, like an "entry point for internationally supplied methamphetamine and/or pseudoephedrine".
By matching the samples with census data, the new research found ecstasy and cocaine were "were correlated with socioeconomic advantage, whereas methamphetamine was correlated with disadvantage".
The biggest concentration of cocaine in the samples was found in Auckland City, where incomes are highest among the surveyed areas. Use of cocaine and MDMA across the three sites was highest near ports, while meth is generally available in rural/poor parts of New Zealand because - as any Breaking Bad fan would know - that's where the labs are.
"Methamphetamine laboratories are often located in more isolated areas to avoid detection," the study noted.
"Unlike methamphetamine (which is both imported and domestically manufactured in New Zealand), MDMA and cocaine are almost entirely imported. They have low availability and low observed use, especially cocaine, likely due to New Zealand's geographic isolation, tight border controls and relatively small market."
That also pushes the price up. A gram of cocaine in New Zealand costs about $374, compared to $95 in the US and even less in some European countries.
Despite Kiwis' fondness of meth, usage here appears to be lower than in the US, Canada and Australia. Our use of cocaine was also low by international standards, but we appear to love ecstasy.
"Mean MDMA consumption was relatively high in New Zealand compared to many parts of Europe and North America. Given the paucity of cocaine, it is likely that MDMA is the substitute New Zealand party drug."
The researchers say the findings could "help guide harm reduction policy for the wellbeing of New Zealand".
"The data confirm the pervasiveness of methamphetamine in New Zealand and supports its ongoing prioritisation in public health and enforcement policy."
