Harmful ‘forever chemical’ increasing in groundwater people rely on for drinking, study warns

Groundwater samples from over 100 wells across Denmark show trifluoroacetate levels have been rising steadily since the 1960s

File. Concerns about health impact of PFAS have been growing in recent years (PA Wire)

A new study has found rising levels of a less-monitored “forever chemical” in groundwater sources, sparking concerns about increasing contamination of drinking water and its public health effects.

Researchers in Denmark found that levels of trifluoroacetate, or TFA, have been rising in groundwater across the country in recent decades, exceeding the amount permissible under European regulations.

Forever chemicals, officially called perfluoroalkyl and polyfluoroalkyl substances or PFAS, are linked to several negative effects on human health but are found everywhere from pesticides and firefighting foams to everyday use products like non-stick cookware and stain-resistant fabrics.

They are called forever chemicals because they fail to break down fully in the environment.

Researchers took groundwater samples from over 100 wells across Denmark and found that the concentration of TFAs has been rising steadily since the 1960s.

TFA forms when fluorinated gases, such as those used in refrigeration, and certain fluorinated pesticides break down in the environment. As these chemicals degrade, they can be carried into groundwater through rainwater and soil.

In recent years, studies from across the world have reported sharp rises in TFA in water sources.

“There are many reports of PFAS contamination of groundwater worldwide, particularly from the historic use of firefighting foams and other industrial activities,” said Stuart Khan, professor and head of school, civil engineering, at the University of Sydney, who wasn’t involved with the research. “These chemicals often infiltrate the soil and contaminate groundwater.”

“It’s not surprising to find TFA given its sources, including as a breakdown product of fluorinated gases used in refrigeration, air conditioning, and electronic manufacturing.”

The new study found that groundwater samples taken from various periods show a noticeable increase in trifluoroacetate levels over time. For instance, groundwater from before 1960 had almost no detectable trifluoroacetate while samples from the 2000s to the 2020s showed an average concentration of 0.6ppb, or parts per billion.

This level exceeds the European Environment Agency’s limit for total PFAS in drinking water, which is set at 0.5 ppb.

“ I think this is the first study to show such a trend in groundwater for any PFAS compound,” Christian Albers, one of the authors of the research, told The Independent.

He explained that while TFA is less harmful than some other PFAS, its higher levels found in the water and the possibility of unknown future health risks could be worrying.

Britain’s Health and Safety Executive has identified TFA as “a substance of concern, since there are indications that it might cause developmental toxicity”.

“We are still learning about the toxic impacts of many types of PFAS, including TFA. Some studies suggest that high levels of exposure to TFA may be harmful to fertility and foetal development, but there remains significant uncertainty,” Dr Khan said.

“The level of risk will be proportional to the level and duration of exposure, with cities that have high levels of industrial activity and poor environmental regulations being most at risk.”

The rise in TFA levels could be due to several factors, including changes in how it settles from the air, absorption by plants, and the use of local pesticides, researchers said.

In Denmark, pesticides that can break down into TFA have been used in agriculture since the late 1960s, the study noted. This historical use of pesticides could have contributed to the rising levels of the chemical in groundwater.

"Some particularly high trifluoroacetate concentrations in groundwater less than 10 years old suggest that recent local sources, such as new pesticide applications, could be becoming more important,” Dr Albers said.

A study published earlier this year showed PFAS are found in surface and groundwater around the world at levels much higher than many international regulators allow.

Despite the availability of water purification methods, PFAS remain challenging to remove.

Conventional water treatment methods are not effective at eliminating them but advanced technologies like reverse osmosis and ion-exchange processes can help remove PFAS.

But these methods are expensive and not always feasible on a wide scale.