Paint in buildings a huge reservoir of PFAS waiting to enter the environment

Painted surfaces in the built environment will likely pose a delayed environmental risk from harmful per- and polyfluoralkyl substances (PFAS) decades down the line, according to a new study. The researchers showed that painted surfaces act like a long-lived reservoir, gradually releasing PFAS into the environment across their lifetime, including use, renovation, demolition and disposal, highlighting a need to better understand this underrepresented and delayed source of PFAS emissions to help inform policy, risk assessments and mitigation strategies.

PFAS, also known as forever chemicals, are a class of highly-stable fluorinated compounds used for their water- and stain-resistant properties in industrial process and consumer products. But because they are so stable, they persist and bioaccumulate in the environment, with long-term exposure linked to serious health problems.

Previous research has tended to focus on the direct release of PFAS from products during manufacture and initial use. But this doesn’t account for emissions during their lifetime, such as from paint in the built environment, which covers huge surface areas and persists for decades.

Now, Daqian Jiang at the University of Alabama, US, and colleagues have created a model that has quantified PFAS retention and emissions associated with architectural paints in the US starting from 2000 with projections up to 2060. To make the model the team collated and integrated various data including PFAS measurements in indoor and outdoor paint products, building stock dynamics, paint consumption patterns, emission kinetics and transportation of waste to landfills.

‘Paint is used pervasively and is designed to last for many years. That combination of widespread use and long service life made architectural paint a potentially interesting product category for understanding PFAS movement through the built environment,’ Jiang says.

Results revealed that in 2020, around 565 tonnes of PFAS were stored in in-use paint in the US, constituting a PFAS reservoir that was 47 times total annual emissions of the compounds from paint in the country. By 2060, the model predicted that around 486 tonnes of these retained PFAS would accumulate in landfill sites, emitting 25 times more PFAS into the environment than in 2020, with hotspots driven by demolition activity and waste routing.

‘We expected that end-of-life accumulation would be important but what surprised us was the extent to which the end-of-life phase dominated the overall picture – it can become an issue years or even decades after the product is first applied,’ says Jiang.

‘One of the most striking findings is not simply that paints contain PFAS, but that the overwhelming majority of the PFAS mass is predicted to remain stored within the buildings for many decades,’ says Patrick Byrne who investigates PFAS in the environment at Liverpool John Moores University, UK. ‘So even if PFAS use in paints were reduced or phased out today, substantial future emissions could still occur from the large quantities already present in existing buildings.’

‘Once we understand when and where PFAS releases are most likely to occur, this type of analysis can help evaluate mitigation strategies – for example, changes in product formulation, building renovation practices, waste management or policy interventions,’ explains Jiang. What’s more, he says the approach could be applied to other consumer materials that likely present the same mechanism of PFAS accumulation via long-lived products followed by delayed release, including flooring, roofing, and insulation.

‘From a broader environmental perspective, the work reinforces the need for better identification of PFAS-containing materials before demolition so that their redistribution in the environment can be monitored and predicted to help reduce future environmental releases,’ adds Byrne.