The presence of perfluoroalkyl and polyfluoroalkyl chemicals (commonly known as PFAS) in surface and groundwater has spread to much of the planet and, in many more cases than previously believed, their concentration is higher than that considered normal. harmless, according to an international study led by experts from the University of New South Wales in Sydney (Australia) published (April 8) in the journal Nature Geoscience. The authors have evaluated the levels of contamination by these compounds also known as 'forever chemicals' (they remain unchanged for many years) in surface and groundwater around the world, highlighting that these resources are used for human supply.
PFAS are a group of more than 14,000 man-made chemicals that have been popular since the 1950s for their various abilities to resist heat, water, grease, and stains.
They are commonly found in household products such as non-stick pans, clothing, cosmetics, insecticides and food packaging, as well as in specialized industrial products such as firefighting foam.
But despite their broad skill set, chemicals have a dark side: They are known as "forever chemicals," since once they are in the environment (or in our bodies) they do not break down further.
PFAS have been linked to environmental and health problems, including some cancers, but much is still unknown about the true scale and potential impacts of the problem, including how much is in our water supply.
A new international study led by UNSW, published today in Nature Geoscience, assessed PFAS contamination levels in surface and groundwater around the world.
It found that much of our global water supply exceeds safe consumption limits for PFAS.
"Many of our water sources are above regulatory limits for PFAS," says the study's lead author, UNSW engineering professor Denis O'Carroll.
"We already knew that PFAS are ubiquitous in the environment, but I was surprised to discover the large fraction of water sources that are above recommended recommendations for drinking water," he says. "We are talking about more than 5 percent, and in some cases it exceeds 50 percent."
The research team gathered PFAS measurements from sources around the world, including government reports, databases, and peer-reviewed literature. In total, they collected more than 45,000 data points, spanning approximately 20 years.
The study also found high concentrations of PFAS in Australia, and in many places drinking water levels were above recommended levels. This typically occurred in areas where firefighting foams had been used in the past, such as military institutions and fire training facilities.
Professor O'Carroll emphasizes that these traces of PFAS are found in water sources, such as dams, and not in the drinking water itself: drinking water passes through treatment plants, some of which are designed to reduce the amount of chemicals like PFAS in our water. before it comes out of the tap.
But some water suppliers (for example, Sydney Water) do not routinely measure the wide range of PFAS that can be found in our drinking water, Professor O'Carroll says.
"The drinking water is largely safe and I don't hesitate to drink it," he says. “I'm also not suggesting that bottled water is better, because that doesn't mean they've done anything different than what comes out of the tap.
"But I certainly think it's worth monitoring PFAS levels and making the data readily available."
The health risks caused by PFAS are not well understood, and there is no scientific agreement on levels that can be considered safe.
According to an Australian government panel of health experts, there is little or no evidence that PFAS pose clinically significant harm to human health, although further afield, body spikes in the US and Europe suggest PFAS are related to adverse health outcomes, such as lower birth rate, infant weight, higher cholesterol levels, reduced kidney function, thyroid disease, altered levels of sex hormones, reduced response to vaccines, and liver cancers, kidney and testicles.
In 2023, the World Health Organization (WHO) declared PFOA, a type of PFAS, a category one human carcinogen.
While PFAS have been linked to many of these health outcomes, they have not necessarily been shown to cause them, but given the potential risks and "forever" nature of these chemicals, many regulatory bodies have strengthened the use of PFAS and introduced safe drinking water limits. as a precaution.
"About 20 years ago, two forms of PFAS initially raised concerns: PFOS and PFOA," says Professor O'Carroll. “These chemicals are regulated to varying degrees around the world. In the United States, the proposed drinking water limits for PFOS and PFOA are four nanograms per liter.”
The study in Australia found that 69% of global groundwater samples with no known source of contamination exceeded Health Canada's safe drinking water criteria, while 32% of the same samples exceeded the hazard index for drinking water. proposed by the United States.
The new study concludes that, overall, "there is a really unknown amount of PFAS that we are not measuring in the environment," says Professor O'Carroll. “Commercial products such as clothing and food packaging contain many more PFAS than we realize.
"This means we are probably underestimating the environmental burden PFAS represent."
Prof. O'Carroll and his team are now attempting to develop their research by quantifying these levels of PFAS from commercial products in the environment.
They are also working to develop technologies that can degrade PFAS in drinking water systems and looking to develop predictive models that determine where PFAS will go in the environment.
