Sickly, skinny tiger snakes living in Perth's urban wetlands have high levels of so-called forever chemicals used in firefighting foam and household goods including cookware and textiles.
Researchers have studied the livers of snakes to better understand the impacts of PFAS - the shorthand name for a large family of chemicals valued for their heat, water and stain-repelling properties.
But the chemicals - some of which are now banned - are an emerging global problem because they don't easily break down but readily move through the environment in water and in the air, building up in plants, animals and humans.
Environmental and human health effects are still poorly understood but a new study has shed light on what's happening to wild tiger snakes living in Herdsman Lake, near Perth's CBD, and Lake Joondalup, on the city's urban edge.
"Tiger snakes in Perth's urban wetlands are ingesting these harmful chemicals and are noticeably skinnier and appear sickly compared to healthy tiger snakes," says lead researcher Damian Lettoof, from Curtin University and the CSIRO.
"They are also experiencing poor muscle and body tone, as well as decreased energy levels."
Dr Lettoof says tiger snakes are a top predator and get most of their pollution exposure from the creatures they eat.
"That means that frogs, birds and lizards in these wetlands may also be accumulating PFAS and need to be tested."
He says the next step will be to examine PFAS levels in frogs.
The snake study found PFAS concentrations in Herdsman Lake were high, relative to other sites.
Researchers weren't surprised, given the wetland is in an older part of the city that gets stormwater from surrounding industrial and residential land, and seepage from landfill.
Stormwater runoff was also likely a factor in PFAS concentrations in Lake Joondalup, with the wetland featuring stormwater drains from surrounding residential land, and two fire stations in its catchment.
Dr Lettoof says more research is needed to work out if PFAS exposure could affect the survival of the snakes, but the study provides an important baseline on how the chemicals could be hurting them.
The most common PFAS chemical found in the snakes was PFOS, or perfluorooctanesulfonic acid.
It was used in firefighting foam until it was banned in the early 2000s but legacy issues remain, including serious contamination problems on and near Australian defence force bases where the foam was used.
Thousands of landholders affected by the contamination reached a $132 million settlement with the Commonwealth earlier this year.
PFAS experts have told AAP there are very few measures to prevent the importation of PFAS chemical residues in imported goods manufactured overseas, including by some of Australia's closest trade partners.
That means Australia still has many active sources of introduction to the local environment, they say.
Previous studies on animals and humans have shown adverse effects of chronic PFAS exposure on the liver, immune function and thyroid hormones.
The tiger snakes study involved Curtin University, the CSIRO, and Western Australia's Department of Water and Environmental Regulation, and Vietnam's Nguyen Tat Thanh University.
It has been published in the journal Science of the Total Environment.
