What are PFAS ‘forever chemicals’?
You may not realise it but you have an intimate relationship with PFAS. The human-made chemicals are in your blood, your clothes, your cosmetics. They have been detected in air, water, soils, sediments, and in rain at levels that would be considered unsafe in drinking water in some countries.
PFAS stands for per- and polyfluoroalkyl substances, it’s an umbrella term for a family of thousands of chemicals – about 12,000 at the last count – that are prized for their indestructible and non-stick properties.
They are used in a huge range of consumer products, including waterproof clothing, furniture, cookware, electronics, food packaging and firefighting foams and are employed in a wide array of industrial processes.
Most PFAS are so well designed and robust that they won’t break down in the environment for tens of thousands of years, earning them the moniker “forever chemicals”. This persistence means the PFAS burden is ever growing, so much so that a group of scientists have concluded that the global spread of just four PFAS in the atmosphere has led to the “planetary boundary for chemical pollution being exceeded, raising risks to the stability of the Earth system”.
The substances’ grease and water repellent properties enable them to be very mobile, which means that once the chemicals have departed their original products they can slide their way out of old landfills for example, and migrate into the environment.
That’s bad news because many PFAS also tend to bioaccumulate, which means they are absorbed by organisms faster than they can be excreted and will build up over time. PFAS biomagnify up food chains too, supplying apex predators such as orcas with hefty doses at mealtimes.
What about PFOS and PFOA?
Little is known about most PFAS because, as The Environment Agency’s former chief scientist put it, “few PFAS have been subject to extensive testing so information about their hazardous properties is … sparse”.
However, two widely used problematic substances – perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) – have been scrutinised following a number of major pollution incidents in the US, Australia and Europe, linked to chemicals manufacturing plants and contamination from PFAS-laden firefighting foams.
Both were eventually banned or had their uses restricted under various European and international laws, but being forever chemicals, they have not gone away.
In the UK today, of the thousands of PFAS in use, only PFOS and PFOA are subject to regulation.
Are they toxic to health?
There’s a hint in the shorthand for the properties of some PFAS, which is PBT: persistent, bioaccumulative and toxic.
So far toxicity can only be applied to PFOS and PFOA, but PFOS has also earned itself an additional letter: uPBT, with the u standing for ubiquitous – a clue as to how widespread the contamination has become.
It was DuPont that introduced PFAS to the world in the 1940s as Teflon and it was DuPont that revealed how harmful they could be. It emitted PFOA from its US plant in south-west Parkersburg into the air and Ohio River from the 1950s until the early 2000s, and it eventually reached drinking water supplies. The ensuing lawsuit, which led to DuPont settling 3,500 personal injury cases for $670.1m (£555m), was made famous by the Mark Ruffalo film Dark Waters.
A US study that ran between 2005 and 2013, involving the collection of blood samples from about 69,000 people living near the DuPont plant, concluded that there was a “probable link” between exposure to PFOA and six diseases: high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer and pregnancy-induced hypertension.
Other studies have reported that PFOS and PFOA can affect the immune system and that by depressing immune response, they can make vaccines less effective. They have also been linked to low birthweight, birth defects, delayed development and newborn deaths in laboratory animals.
Ian Ross, PFAS practice lead at engineering company CDM Smith, said: “It was known that PFAS are extremely persistent in the environment since at least 1950 but they have been widely used in highly dispersive applications such as in firefighting foams since 1962.”
Public interest science has only just begun to wrap its head around PFOS and PFOA, decades after they were first produced, and so there is little chance it will ever catch up with manufacturers, who can tweak an existing molecule, rename it, and have it on the market in a fraction of the time it takes to establish a body of evidence to demonstrate whether or not it needs regulating.
It’s a high stakes, slow motion game of whack-a-mole.
How do you become exposed?
It’s estimated that, given the widespread use of PFAS and the ubiquitous presence of some of them in the environment, almost everyone on the planet has PFAS in their blood at some level.
For the general public, the main sources of PFAS exposure are from drinking water and food, such as eating fish, eggs, or milk, or livestock that has fed on contaminated land. Direct exposure can also come via cosmetics, sprays or dust from consumer products, but little is known of the impacts through these pathways.
But to fall foul of the worst effects of PFOS or PFOA, you would need to be exposed for a sustained period of time to pretty high concentrations of the substances. That’s why most PFAS health scandals in the US and Europe have been related to contaminated drinking water supplies.
There are lots of potential sources of PFAS pollution. Aside from chemicals manufacturing plants, any site that has regularly used PFOS-laden aqueous film-forming firefighting foams, such as airfields, military bases and firefighting training grounds, could in theory contaminate soils, air and water in the vicinity.
Other sources include landfills, paper mills, wastewater treatment works, land spread with sewage sludge, runoff from urban areas, industries that involve textile waterproofing, metal finishing and plating, carpet and furniture production, paint, refrigerators and cleaning products.
PFAS “behave like surfactants, like soaps”, says Prof Crispin Halsall, an environmental chemist at Lancaster University. “They sit at the interfaces between water and particles, water and biota, they can transfer to the atmosphere and they’re so abundant they cycle around the wider environment, and that’s the problem we’ve got.”
Add to this the minefield of consumer products laden with PFAS, the existing load in the environment, while at the same time more PFAS are being manufactured and created, and it is hard to imagine how at least low-level exposure could be avoided.
What do PFAS do to the wildlife and the environment?
PFAS have been detected in even the remotest parts of the globe, from the Arctic to Antarctica.
In England many rivers fail to meet standards for chemical health due to the presence of PFAS, and this widespread pollution could be affecting the wildlife that live in them. Cardiff University analysed the livers of otters across England and Wales and found PFAS in all 50 otters sampled, with 12 different types of PFAS found in 80% of the animals. At sea, PFAS have been found in killer whales near Norway and in bottlenose dolphins stranded along the northern Adriatic coast.
In Flanders, the government has advised people living in the neighbourhood of a 3M PFAS factory to stop eating eggs and vegetables from their hens and gardens, and a study by the Technical University of Denmark National Food Institute and the Danish Veterinary and Food Administration found that organic eggs in Denmark are contaminated with high levels of PFAS.
Linda Birnbaum, toxicologist and former director of the US National Institute for Environmental Health Sciences, said: “There’s an increasing amount of data showing PFAS are associated with a wide variety of health effects, not only in people but in animals.
“I like to remind us all that we are a kind of animal … there are now hundreds of epidemiology studies showing associations with a wide variety of effects, including cancer, liver effects, kidney effects, effects on development and reproduction, growing evidence for effects on neurodevelopment, growing evidence for effects on type 2 diabetes … It’s kind of like the more you look, the more you begin to find associations with this very broad class of chemicals.”
