Scientists say PFAS chemicals could be responsible for drop in Phillip Island seal numbers
Researchers say elevated levels of firefighting chemicals in seals off Victoria’s Phillip Island could be playing a role in declining numbers.
A research project between the University of Sydney, the National Measurement Institute and Phillip Island Nature Parks, has studied the colony at Seal Rocks since 2006.
The research team was initially focusing on other chemicals but realised PFAS — harmful chemicals traditionally found in firefighting foam — were more important.
There are about 20,000 seals that call the island of Seal Rocks off Phillip Island home, making it the largest colony in Australia.
But that number is dropping.
“It’s quite a large drop in number of pups that we’re estimating out there: 25 per cent. That’s a quarter of the amount of pups we’d estimated prior to 2007,” Phillip Island Nature Parks research scientist Rebecca McIntosh said.
Dr Rachael Gray from the Sydney School of Veterinary Science said PFAS chemicals were particularly bad for seal pups.
She said high concentrations of the chemicals had passed through to seal pups in gestation or in their mothers’ milk.
“We mainly focused on assessing pup values, that we actually have these chemicals present that can actually affect development, stunt growth, reduce survival and impair the immune response,” Dr Gray said.
“We tested some adult animals as well and we found they have high concentrations in the tissues that we sampled.
“Basically, they don’t seem to break down at all once they’re in the environment.”
PFAS banned abroad
PFAS — or per- and polyfluoroalkyl substances — is the broad name for 4,700 chemicals that do not break down and instead accumulate in soil, water and human bodies.
The chemicals were used in firefighting foams at Australian defence bases until the early 2000s.
“They’ve been banned in New Zealand, they have been banned to some extent in the USA, South Australia has banned their use, and New South Wales has partially banned the use of those firefighting foams just recently in March.”
But they have not been banned in Victoria.
Chemicals linked to health problems
At a national level, the Australian Health Department says exposure to PFAS can be linked with mildly elevated levels of cholesterol, effects on kidney function, and the levels of some hormones.
“However, these effects are small and generally within ranges seen in the general population, a department spokesman said, adding that “PFAS has not been shown to cause disease in humans”.
That view differs from other international health agencies, such as the European Environment Agency, which has “high certainty” of other links to liver damage, kidney and testicular cancer.
Seals not the only animals affected
Dr Gray says research from North America shows sea otters with PFAS in their blood are more likely to get infectious diseases and Australian fur seals are closely related to sea otters and bears.
But more work needs to be done to see if there’s been a reduction in breeding females, or a reduction in how many pups they’re having.
“We’re in the process of working that out by using drone images,” Rebecca McIntosh said.
The images are posted to the SealSpotter website where citizen scientists can help to count seals.