Healthcare (Commonwealth Union) – The Health hazards of Per- and polyfluorinated alkyl substances (PFAS) or forever chemicals have been widely documented across the globe. Their ability remains in the environment and stay in our bodies for long periods of time have been one of the most concerning. Last year 21 new PFAS were found in tap water in Sydney, Australia.
One of New Zealand’s treasured native plants, harakeke, is showing potential as a way to remove “forever chemicals” from drinking water.
PFAS have been linked to health issues such as cancer and reduced fertility, and traces of these chemicals have been detected in the blood of both humans and animals worldwide.
Laboratory tests conducted at Waipapa Taumata Rau, the University of Auckland, found that chemically treated harakeke performed better than several other water purification methods that were evaluated.
Dr Lokesh Padhye says the results indicate that this native plant could form the basis of a cost-effective solution for removing PFAS from drinking water.
He serves as an honorary academic in the Faculty of Engineering and Design and as Associate Director of Emerging Contaminants Research at the New York State Center for Clean Water Technology.
Padhye indicated that there is still further research required, but the sustainability and ready availability of the material make it especially encouraging.
The chemicals are referred to as “forever chemicals” because they do not easily break down in the environment.
Professor Melanie Kah of the School of the Environment indicated that removing forever chemicals would further highlight the extraordinary versatility of harakeke.
Before colonisation, Māori made extensive use of harakeke fibres to produce baskets, ropes, clothing, mats, bird snares, and fishing nets. The plant’s nectar served as a natural sweetener, dried flower stalks were fashioned into rafts, its sap was used medicinally, and juice from the roots acted as a disinfectant. (Despite its common name, the plant is actually a lily rather than a flax.)
In laboratory tests, chemically treated harakeke fibre successfully removed five types of PFAS from water, including three “short-chain” PFAS—considered the most difficult to eliminate—according to PhD researcher Shailja Data.
During the experiments, small containers were filled with contaminated water along with strands of processed harakeke that had been chemically modified to attract PFAS molecules.
After the containers were mechanically shaken for 24 hours, between 70% and 99% of the individual short-chain PFAS had been removed, outperforming the other materials evaluated in the study, Data reported.
“The strength of the plant’s fibres is a big plus – they don’t easily fall apart,” she explained.
The project emerged from earlier research by Professor David Barker from the School of Chemical Sciences.
In 2019, Māori parents at his children’s school raised concerns about plans to remove harakeke, arguing that the plant helped purify water in a nearby stream on the school grounds.
Curious about the claim, Barker began studying the plant as part of the government-funded Science for Technological Innovation programme led by the University of Canterbury. Laboratory experiments showed that chemically treated harakeke fibres could remove nitrate from water, although the research team later shifted their focus to other materials for that purpose.
The current PFAS study is a collaborative effort involving environmental, engineering, materials, and chemical scientists from the university, and now extends internationally following Padhye’s move to the New York State Center for Clean Water Technology at Stony Brook University.
Associate Professor Erin Leitao, a materials scientist in the School of Chemical Sciences and co-author of the study describing the experiments, is leading further work to identify alternatives to so-called “forever chemicals.”
“Dealing with forever chemicals is a daunting task, but it must be done,” she explained.
