Facing the future by cleaning up the past

Associate Professor Denis O'CarrollAssociate Professor Denis O’Carroll explains the problem of emerging contaminants in our water, food and bloodstreams, and his mission to develop sustainable remediation technologies to clean up contaminated sites.

Just how big a problem we face in Australia regarding the proliferation of per- and poly-fluoroalkyl substances (PFAS) and perfluorooctanoic acid (PFOA) in our water supplies remains to be seen. But with contaminated sites being increasingly identified across our nation, and across the globe, the race is on among researchers to figure out how to break down and neutralise these incredibly resistant and potentially harmful compounds.

“PFAS and PFOA are very stable chemical compounds which have been used in the manufacture of a wide range of commercial and industrial applications since the 1950s,” says Associate Professor Denis O’Carroll, Director of UNSW’s Water Research Centre, and an expert in engineered nanoparticles in the environment, particularly in groundwater systems. “They are effective for stain, oil and water-resistant consumer products but also appear in cleaning products, paints and firefighting foams.”

The big problem is that the stability of these compounds makes them incredibly persistent in the environment. They are being found in many natural sources of water and in fish, animals and humans too.


O’Carroll explains that PFOS and PFOA in firefighting foams are a particular problem because they have been used extensively across the world for nearly 50 years. They work by spreading foam on the fire (which smothers the oxygen and puts out the fire) and in some repeatedly used fire training areas they appear in scarily concentrated levels. “There is a pressing need to develop clean up technologies because currently there is no way to remediate sites like this,” he says.

In one well-publicised Australian incident in 2016, toxic chemicals used in firefighting foam leaked from the Williamtown RAAF Base in NSW and were subsequently found in the local water and food supplies. The Department of Defence continues to investigate other sites for contamination, and chemicals have already been detected in other areas of Queensland and Victoria.

“The big problem is that the stability of these chemical compounds makes them incredibly persistent in the environment. They are being found in many natural sources of water and in fish, animals and humans too. In the US, for example, 97% of the population has measurable quantities of these manmade compounds in their blood,” he continues.

In addition to not degrading in the environment they have been found to easily move from soil to groundwater and can also travel long distances. Some studies suggest that almost every person on Earth has these compounds in their blood which gives some indication of the scale of the problem.

O’Carroll says that although alarm bells have been ringing since the 1990s only recently has there been a monumental shift in our thinking about the health impacts and risks. There is still a lot of uncertainty and much debate around the health implications, but they have been linked to cancer and immune suppression in infants.

Currently O’Carroll has teamed up with UNSW colleagues Professors Mike Manefield, Stuart Khan and Dr Matthew Lee on an ARC research project which will specifically address the PFAS problem.  “Although currently, we have way more questions than we do answers,” O’Carroll says, “my hope is that our work will go some way to help accelerate the eventual solutions.”

Originally published on www.engineering.unsw.edu.au

For further information contact:

Denis O'Carroll | Associate Professor | d.ocarroll@wrl.unsw.edu.au


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