Filtering the wastewater samples at the ESR lab. Photo: Ellen Rykers / RNZ
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Wednesday mornings are sample arrival time at the ESR lab in Ōtautahi Christchurch.
Chilly bins filled with brown glass one-litre bottles arrive from councils around the country. Their contents – a brown, foul-smelling liquid, unpleasant to inhale, but containing a wealth of information – are our wastewater.
The 2020 throwback
Remember when the 1pm daily update was one of the most watched shows? This is when ‘wastewater-based epidemiology’ really shot to fame.
ESR, a crown research institute, continues to use wastewater testing to identify different communities where the virus that causes Covid-19 is circulating.
But the pandemic was not ESR’s first foray into wastewater testing. In fact, since a pilot in 2016, and expansion of testing nationwide in 2018, a team in Christchurch has been continuously testing wastewater from around the country for the presence of illicit drugs.
The ESR wastewater analysis team. Photo: Ellen Rykers / RNZ
The National Drugs in Wastewater Testing Programme is a collaboration between the National Drugs Intelligence Bureau of the New Zealand Police and ESR. Each week wastewater arrives to the ESR lab in Christchurch, to be processed under the watchful eye of senior scientist Andrew Chappell.
Here the samples are filtered and concentrated, and then analysed for specific illicit drugs and their metabolites – what the body produces when someone consumes these drugs. The results of the presence and quantity of each drug then gets passed on to the New Zealand Police, who publish the results quarterly, and use them to make decisions.
And the success of the programme inspired others.
From drugs to alcohol
From investigating alcohol consumption and looking for health biomarkers, to answering questions about cigarette smoking versus vaping and learning about our exposure to environmental contaminants, Dr Lisa Pilkington of the University of Auckland thinks there’s a lot of untapped potential in our wastewater.
“You can get such a wealth of information… at a population scale, about what’s happening in the community. And then you can do that in a very quick and efficient, near real-time way.”
The ‘first cab off the rank’ was investigating alcohol consumption. Master’s student Miriama Wilson (Ngāti Kahungunu ki Wairoa, Ngāti Tūwharetoa, Ngāti Raukawa) got stuck into this, working closely with Andrew in the Christchurch lab to process the wastewater samples.
Miriama Wilson and Dr Lisa Pilkington at the University of Auckland. Photo: Claire Concannon / RNZ
She wasn’t looking for alcohol itself, however. Instead, she was looking for ethyl sulphate – the metabolite that our bodies produce when we drink alcohol.
From identifying the tiny amounts of these metabolites, she then back-calculated to work out how much alcohol was consumed in the community. From there, population statistics allowed her to work out a ‘per capita’ amount of alcohol consumed for comparison between locations.
For this pilot, Miriama investigated ten sites across six months – four in Auckland, and the others scattered around the North and South Islands: Palmerston North, Wairoa, Dunedin, Queenstown, Westport and Christchurch.
The interesting peaks and patterns
The research took place in 2021 and covered a period of time when Auckland went into lockdown. Miriama could see drinking habits changed as the communities moved from Level 1 to Level 2 restrictions – not an increase, but rather a shift in the pattern of when people were drinking. In a normal week people tended to drink more on the weekends, but at Level 2 the drinking spread out across the week.
Comparison of locations revealed that in general those living rurally, in smaller population centres, tended to drink more than those in urban areas. Westport had the highest consumption, with Queenstown next, and West and South Auckland at the lower end. The overall average result was 12.2mL/person/day, which works out to be around one standard drink.
What was especially interesting were the peaks that Miriama saw in different locations on different days. When she found a peak in her analyses she would look back to see what was happening at that time – an All Blacks game on this day, a Super Rugby match in the local stadium on that weekend, and for one massive Dunedin peak – Friday night of O Week (University of Otago’s Orientation week for new students).
Andrew Chappell with the mass spectrometer for identifying drugs in wastewater samples. Photo: Ellen Rykers / RNZ
Alcohol is New Zealand’s most harmful drug, with a recent report estimating the total societal cost of alcohol harms in 2023 as approximately $9.1 billion. Te Whatu Ora has shown interest in Miriama’s research, and she’s hoping that they might take the step to continue monitoring long-term, which would enable assessing the impact of any interventions.
But both Lisa and Miriama are already looking to the next projects.
Miriama plans to pursue a PhD to look at a prostate-specific antigen in wastewater – a biomarker related to prostate health and cancer. It’s a piece of research that feels distinctly personal to her – her grandfather passed away from prostate cancer and Māori men are about two times more likely to die from prostate cancer than non-Māori men.
Lisa and Andrew are currently helping another master’s student, Hea Jong Kim, to write up her research using wastewater to investigate nicotine consumption, and the relative contributions of cigarette smoking and vaping.
For Lisa, the benefits of wastewater epidemiology are in its anonymity and its efficiency.
“It’s just really digging down into community habits - in a non-targeted way, in a broad way, but something that just gives you a lot of information that you can [use] to potentially have such great positive impacts for the community.”
Listen to the episode to learn more about Miriama’s research and plans, and to visit the ESR lab in Christchurch to follow the steps in sample processing.
Learn more:
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The Detail also did an episode on this topic in 2022, delightfully called ‘Spying on our sewage’.
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Our Changing World also covered New Zealand’s world leading approach to Covid-19 sequencing during the pandemic.
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Dig into the data yourself. Miriama’s research has been published online and the New Zealand police publish their data quarterly.
