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PFAS experts answer common questions about 'forever chemicals' and the risks to human health
PFAS, it seems, are everywhere.
From farmers in Queensland managing contaminated land, to residents north of Perth fighting for tainted pipework to be replaced, Australians are grappling with how to live with so-called "forever chemicals".
Last week, a New South Wales Health expert advisory panel delivered its report on the health impacts of PFAS, on the same day researchers confirmed 21 new PFAS chemicals had been detected in Sydney's tap water.
With a Senate inquiry into the extent, regulation and management of PFAS looming, some academics are encouraging a rethink on the essential use of these substances.
To better understand how "forever chemicals" work, what the risks are, and what's being done to address the problems, we sat down with three leading PFAS experts:
These researchers, who have a combined six decades of experience in the fields of environmental science, engineering and molecular toxicology, are urging caution around what they've called a growing problem.
Have you got a question about PFAS? Dr O'Carroll will join us live from 11am to answer the common questions about forever chemicals.
Per- and polyfluoroalkyl substances (PFAS) refers to a group of over 14,000 synthetic chemicals used in all sorts of industrial and domestic products since the 1950s.
They're often used in firefighting foams, pesticides, building materials and electronics, as well as household products such as stain-resistant upholstery, waterproof clothing, cleaning products, cosmetics, food packaging and non-stick cookware.
Dr O'Carrol explains that the chemical properties of PFAS make them very effective at repelling water, oil and dirt.
"It's a chemical that likes to be at interfaces … it doesn't let water through jackets, doesn't allow wine to stain our carpets," he says.
Dr Clarke adds "anything that is advertised as oil- or water-repellent is likely to have a PFAS in it".
"It has a carbon-fluorine bond, which is very strong, and it doesn't degrade easily in the environment … they get the term 'forever chemicals' because they don't really degrade," he says.
The durability of PFAS means they can persist in the environment — and in the bodies of humans and animals — for a long time, and this presents significant concerns.
According to the latest National Health Measures survey, most Australians have detectable levels of PFAS in our blood.
The most common types detected are perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS), found in more than 85 per cent of the population.
The Australian government's PFAS taskforce notes these chemicals aren't directly manufactured in Australia, but we do know they are found in products we use and traces have been found in the environment.
Dr DeWitt says most people are exposed to PFAS through ingestion — the water they drink or the food they eat.
Pioneering research by Dr O'Carroll, in collaboration with international scientists, tested 45,000 soil and groundwater samples from around the world, and found "a substantial fraction" had PFAS levels exceeding safe drinking water guidelines.
The highest PFAS levels tended to be around known exposure sites, including training areas where firefighting foam had been in high use, or around landfills.
Levels of PFAS have also been detected in water filtration plants in Sydney, in compost being sold to the public in Western Australia, and in the nesting soils of little penguins around Tasmania.
Last year, Australia updated its guidelines around safe drinking water to reduce the accepted levels of several PFAS chemicals.
Dr DeWitt says less is known about other routes of exposure, such as skin absorption or inhalation.
"But we know that when PFAS are [ingested in food or drink] the bulk of what you take into the body can get absorbed across your intestines and get into your blood," she says.
Dr DeWitt says once PFAS are distributed throughout the body, they can cross cell membranes and interact with proteins that affect various bodily functions.
"Some of these proteins can affect vitally important processes in our bodies, such as the production and action of hormones, the production of cholesterol. So they can interact with these physiological proteins in the body to produce toxicity," she says.
Researchers say one of the biggest concerns with PFAS is their persistence — that is, how long they hang around in our bodies.
"Many PFAS get excreted in the urine, so they travel from the blood to the kidneys, where they can get pushed out of the body whenever somebody urinates," Dr DeWitt says.
But this can take a long time.
For some PFAS, the half-life — that is, the time it takes for half of the amount ingested to be excreted — is a matter of hours or days, but for most, it's years.
"The problem is, even if you have low levels of exposure, you can still build up amounts in your body if what you rake in is greater than what you put out," Dr DeWitt says.
The science on PFAS and the potential impact on human health has been the subject of much public debate in the past few years.
Not all of these 14,000 chemicals have been closely studied. Most research has focused on the effects of well-known PFAS, often in populations who have been exposed to high doses.
From that research, PFAS exposure has been associated with increased levels of cholesterol and uric acid in the blood, reduced kidney function, altered immune function and levels of thyroid hormones, delayed menstruation, earlier menopause and lower birth weight.
The Australian Health Department's PFAS guidelines note these differences have generally been small and unlikely to cause significant negative health outcomes.
And less is known about the toxicity of these chemicals at low doses over time.
However, Dr DeWitt notes several large-scale epidemiological studies of people who have been highly exposed to PFAS have led to some concerning findings.
"Right now, PFOA has the strongest evidence of links to cancer, followed by PFOS. For the others, there haven't been enough studies to understand if they are linked to cancer," Dr DeWitt says.
"But we also have evidence from experimental studies with animals like mice and rats to support what we observe in exposed people, which gives biological plausibility or credibility to those findings in people."
The NSW Health advisory panel's report on PFAS, published last week, concluded that "health effects of PFAS appear to be small", and cautioned authorities to "avoid using currently available epidemiological studies to derive threshold levels due to the higher risk of bias".
Dr Clarke warns that while more research is needed, there are potential risks we should be mindful of.
"We know that there's a lot of harm from particular types of pollutants, so I'm talking about cancers, reproductive health problems, impaired immune systems, and neurological damage.
"We've seen a 50 per cent decline in male fertility over the last century, which many researchers believe is associated with exposure to chemicals."
In a group of more than 14,000 chemicals, not all PFAS are the same.
Researchers use several criteria to evaluate the harm of different PFAS chemicals, including how persistent they are in the environment, whether they accumulate in the bodies of humans or animals, and whether they produce toxicity.
The bulk of the research to this point has focused on the impact of what are known as longer-chain PFAS, including PFOA, PFOS and PFHxS.
The structure of these long-chain PFAS is understood to play a significant role in toxicity, and they are generally highly mobile in water, which means they can travel long distances in the environment.
Certain long-chain PFAS, such as those used in firefighting foams, have been phased out around the world and Australia introduced a ban on PFOA, PFHxS and PFOS in July.
But Dr DeWitt warns that PFAS with shorter carbon chains may still be harmful.
"A short-chain PFAS is as equally persistent in the environment as a longer-chain PFAS. So whether a PFAS has eight carbons or four carbons, it doesn't break down," she says.
"The difference is that the shorter-chain PFAS tend to get excreted more rapidly from the bodies of living organisms … that does mean that they have a lesser opportunity to interact with molecules in our bodies to produce toxicity, but they can still produce toxicity."
Dr Clarke says there's still a lot we don't know about newer PFAS, including their effects on our bodies or the environment.
"But we can reasonably predict that they will be persistent [in the environment] because of that perfluoro–carbon bond, which is very strong," he says.
"So [while] we don't have full scientific evidence to demonstrate that it causes an environmental harm, we can reasonably predict that it will, because it has similar properties to things that we've already banned or phased out."
Dr DeWitt wants the conversation to focus on what we really need PFAS for, and to consider limiting our use to chemicals that are "essential for the health, safety and functioning of society, and for which there are no alternatives".
"So, do you have to have a sofa in your house that has a stain-resistant coating? Is it really that difficult to remove stains with soap and water?" she says.
"Do you have to have PFAS in your dental floss so that it glides perfectly between your teeth?
"I think we need to think about the essentiality of chemicals before we put them in products."
The experts say, while products like non-stick cookware and cosmetics are not thought to be a major pathway for PFAS to get into the body, there are still choices you can make to reduce exposure.
"The teflon pan isn't really thought to be an exposure source to people … be mindful about how you use it, though. If you're burning it, and you see smoke coming off it, that's a sign that you shouldn't be using it at that temperature," Dr Clarke says.
As for cosmetics and personal care products, if you want to avoid PFAS, check ingredients lists for any chemical with "perfluoro" in the name.
