For months I have been looking at the construction of our new garage. The breeze block walls have been built, sofas are in place under the eaves, the concrete floor has been cast and slate tiles are fixed to the roof. Soon it’s time to finish the outside with sand and cement, seal and waterproof the walls, varnish the new fence and finish it all with a shiny paint.
That means another trip DIY store, where the shelves are full of marketing appeals. Glossy varnishes promise to color wood for five years. Fence treatments are UV-resistant and rainproof within half an hour and protect against rot. Masonry paint is no longer just about the paint: do I need pure luminous or ultra-soft, anti-mold or weather-resistant?
Many of these objects rely for their seemingly magical properties on PFAS (per- and polyfluoroalkyl substances), known as “forever chemicals”. This group of synthetic chemicals is used to prevent corrosion, reduce friction and make products waterproof and stain resistant. Used in everything from cosmetics to Food packaging, PFAS also appears in paint (as a binder and to give a smooth finish), wood varnish (for oil and water repellency and stain resistance) and sealant. They are used in the top layer of solar panels, artificial grass and fire extinguishing foam.
PFAS ‘incredibly strong carbon-flour bonds mean that these chemicals are not biodegradable. Renovations will not last forever but PFAS remains and accumulates in soil, water, air, wildlife and our bodies. PFAS has been found in human breast milk and blood from 97% of Americans. Exposure to certain PFASs has been linked to fertility problems, metabolic changes and an increased risk of obesity and cancer — but so much is still unknown about their long-term consequences.
Eroded by the elements or dumped into drains, PFAS ends up in the water system. Once there, it is impossible to fix – remove the contaminants. Water treatment plants can use activated carbon to filter out some, but not all, PFAS and other pollutants, but it is expensive and requires high temperature combustion. Most chemicals from the silky smooth, painted wall or the stainless steel railing end up in the sea.
Globally PFAS has been extensively documented in rivers, lakes, wetlands and every sea; they are on Mount Everest and in Arctic sea ice. But they are most common where there are many people – in the river basins of European cities, for example.
“Everywhere there is society, there is the use of PFAS,” says Prof Ian Cousins, an environmental chemist at Stockholm University, who has studied this huge, diverse group of chemicals for 20 years. “PFAS rains everywhere – you can find them in rainwater wherever you live in higher concentrations than the environmental standards of rivers.”
Cousins think this is a bigger problem than we have acknowledged. “We should not release these artificial substances into the environment because they cycle around in water systems. Some turn into more harmful PFASs before returning to the air from the oceans and then raining down to land. The upstream solution is not to use these persistent chemicals in the first place. ”
However, the market for PFAS-only building materials is worth $ 26 billion (£ 19 billion), according to American Chemistry Council (compared to $ 753 billion for the semiconductor industry). Two of the most widespread and dangerous – PFOA (perfluorooctanoic acid), which is used to make Teflon and PFOS (perfluorooctane sulfonic acid) – have been phased out in most of the world but remain in the oceans. PFOA and PFOS were most harmful at the manufacturing stage, where factory workers were exposed.
But not all PFASs are toxic to humans: chemistry is much more nuanced. “Mapping the PFAS universe and trying to understand which ones are bad and which ones are not an important activity, but it will take decades [to calculate] and then it may be too late to do anything about it, says Cousins.
Some PFASs used in building materials include large molecules, such as fluoropolymers, which are used as coatings on roofs, which are not released when it rains. But they leak into the ground when a building is overturned and goes to landfill. Substances that add water repellent or are used to make paints, inks, paints and varnishes are more immediate for the environment, as they have less residual PFAS molecules that are easier to wash.
Many short-chain PFASs dissolve in water. In the sea, most remain close to the surface, in a layer between 50 and 200 meters deep. Gradually mix this layer with deeper water. Some chemicals sink, end up in sediments or in the marine food chain; others remain in the water column. Some, like PFOA, act as detergents, repelling water and rising back to the surface to be released back into the atmosphere; Cousins and his team found that some PFASs are released as marine aerosols or drops in sea spray when wave motions create air bubbles.
In fact, sea spray aerosols from the sea are the largest source of atmospheric PFAS. There, they can “affect climate and cloud generation and all sorts of things,” Cousins says. In the Great Lakes region of North America, PFAS levels in precipitation exceed it for other old pollutants, e.g. mercury and pesticides.
Cousins recommends that manufacturers take precautionary measures by designing biodegradable alternatives. Some PFAS-free alternatives are available. Roofing materials can be made with silicone or acrylic coatings. Acrylic can be used to make paints durable and glossy. Silicone or paraffin wax can cause wood varnish to repel water; silicones and epoxy resins can seal porous building materials.
But since ingredients are not always listed on the jar, it is difficult for shoppers to make informed decisions. A simple guide is to avoid anything labeled as perfluoro, polyfluoro or fluoro, which indicates that they contain PFAS.
And it’s not just amateurs who make their home who can vote with their wallets. Owners of large buildings, such as hospitals, universities and commercial real estate developers, also have very focused purchasing power, according to Hannah Ray, of the Green Science Policy Institute. She wants PFAS chemicals to be limited to essential use only, where no viable alternative is available. Some progress has been made, she says: “Germany, the Netherlands, Denmark, Norway and Sweden have submitted their intends to limit PFAS as a class and the US state Maine will ban most things use of PFAS from 2030. “
The Green Science Policy Institute warns of “regrettable substitution” – replacing a dangerous PFAS with a slightly different PFAS that has not yet been shown to be toxic.
In the meantime, I am looking for safer PFAS-free alternatives for my garage, such as linseed oil to cover the wooden fence and water-based “eco” paints, even though these also contain small amounts of PFAS as a binder. Cradle 2 Cradle-certified construction products the list is a good place to start, and if there is a choice between gluing something or mechanically fixing it together with screws, I will choose the latter, because otherwise it is difficult to know what the long-term effects of my choices will be.
“Some PFASs can have catastrophic effects, but it’s hard to predict,” says Cousins. “We were able to discover that we have all used a chemical that will make us sick but that is very difficult to remove from the environment.”