As animals living side-by-side with humans, researchers at the University of Melbourne decided that the city\u2019s possums could be a good test of urban pollution, and made a study of the presence of PFAS in their livers.\u00a0<\/p>\n
\u201cPFAS have been studied widely in aquatic animals, but we know very little about the health impacts of PFAS in terrestrial wildlife, and this is the first study to investigate PFAS levels in Australian marsupials,\u201d said first author and PhD student Ellis Mackay in a statement<\/a>.<\/p>\n The results are alarming, particularly when it comes to brushtails. The authors found liver concentrations of 16-266 nanograms per gram (parts per billion by weight), with a median of 74 ng\/g. This, they note, \u201cis comparable to levels reported in rodents sampled both 3 kilometers (1.9 miles) and 101-200 meters (330-660 feet) away from a chemical-waste site used to neutralize, stockpile, and dispose of hazardous and non-hazardous waste (including persistent organic pollutants) in Nevada.\u201d More and more evidence as to the health effects of PFAS is coming out, some of which the companies that make them knew about for years, but hid<\/a>.\u00a0<\/p>\n Ringtails are considerably healthier on this score, with a median of 16 ng\/g. The mix of chemicals is also different, with ringtails apparently having mostly ingested PFAS precursor molecules, while the brushtails encounter PFAS directly. Study author Dr Jasmin Hufschmid<\/a> told IFLScience, \u201cThere might be differences in metabolism,\u201d but the team think the stark contrast probably primarily reflects different diets. Ringtails feed almost entirely on fruit and leaves.<\/p>\n This illustration depicts potential PFAS exposure routes for common brushtail and ringtail possums in an urban ecosystem in Melbourne, Australia.<\/p>\n Image credit: Mackay et al., Science of The Total Environment 2025 (CC BY 4.0<\/a>)<\/p>\n Brushtails are more opportunistic, supplementing those foods with birds\u2019 eggs, soil invertebrates, and the contents of humans\u2019 rubbish bins. \u201cBirds eggs are known to accumulate PFAS, particularly PFOS, Hufschmid told IFLScience, adding, \u201cBrushtails also spend more time on the ground,\u201d while ringtails have little direct soil exposure.<\/p>\n Mackay<\/a> told IFLScience there have been no equivalent studies published on animals with similar urban lifestyles elsewhere, of which she said raccoons are probably brushtails\u2019 closest international counterparts. \u201cThere is one study on red foxes in Oslo, whose PFAS levels were 10 ng per gram,\u201d Mackay said. As primarily carnivores, foxes would be expected to bioaccumulate<\/a> toxins more than more herbivorous possums.<\/p>\n Mackay told IFLScience: \u201cMarsupials might be really bad at processing these chemicals, or perhaps Melbourne is just much more polluted than Oslo, or maybe the foxes don\u2019t come as far in.\u201d To test that, Mackay intends to study Melbourne\u2019s own foxes, which have become an invasive species.<\/p>\n The team didn\u2019t find any pattern based on the age or sex of the possums in the study, but there are many other questions they can\u2019t answer. The possums were provided by veterinary clinics that had needed to euthanize those brought in for ill health or injury. Consequently, the authors acknowledge, they may not be representative of the population overall. However, if high levels of PFAS exposure mean possums are more likely to become so sick they have to be put down, that\u2019s even more reason to worry about our own exposure<\/a>.\u00a0<\/p>\n No data is available on why the possums died, or their geographic locations within the city. Hufschmid explained, \u201cVeterinary clinics often see wildlife for free, particularly when for euthanasia, so they\u2019re overstretched and not keeping detailed records. We just get a bag of possums to study.\u201d Even when the possum\u2019s body might tell the researchers what happened, such as after a car accident, the team didn\u2019t keep records.<\/p>\n The lack of geographic data means the team can\u2019t pin the PFAS on a specific source. Although more than 7 million PFAS chemicals have been produced, Hufschmid told IFLScience that the mix of specific chemicals also doesn\u2019t reveal much about where they are coming from. \u201cA lot have varied applications. PFOS is one of the most common ones, which has many uses,\u201d Hufschmid said. Although there are some large-scale sources, such as firefighting chemicals used at specific locations, PFAS is also used to make furniture and clothes water-resistant.<\/p>\n![\"Graphical](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/11\/1-s2.0-S0048969725023678-ga1_lrg.jpg\" "\\"Graphical")
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