Scientists discover process to destroy harmful ‘forever chemicals’

Scientists in the US have discovered a simple method for destroying harmful chemicals previously thought to be almost indestructible that pose a growing global pollution problem and health risk.

Synthetic compounds — technically called per- and polyfluoroalkyl substances or PFAS, but commonly known as “forever chemicals” — have been used for decades in industrial and consumer products, from waterproof fabrics and firefighting foams to non-stick cooking pans. They accumulate in the environment due to their chemical stability, potentially posing a threat to human and animal health.

Chemists from Northwestern University in Illinois and the University of California Los Angeles have developed an inexpensive, low-energy process that breaks down two of the most important classes of PFAS into harmless chemicals. The discovery was published in the journal Science on Thursday.

“PFAS have become a major societal problem,” said William Dichtel, project leader at Northwestern. “Just a tiny amount of PFAS causes negative health effects and it does not break down [in the environment]. We can’t just wait out this problem.”

Exposure to PFAS depresses the immune system, decreases infant and foetal growth and increases the risk of kidney cancer in adults, according to a report by the US National Academies of Sciences, Engineering and Medicine published last month. It also found evidence that suggested links with other cancers.

“We wanted to use chemistry to create a solution that the world can use,” said Dichtel. “It’s exciting because of how simple, yet unrecognised, our solution is.”

The process, which the scientists say marks a breakthrough, involves heating PFAS to about 100C with sodium hydroxide in dimethyl sulfoxide, a common solvent. This sets off a series of reactions that destroys the otherwise unbreakable chemical bonds between carbon and fluorine atoms that make PFAS so stable. The products are harmless, small organic molecules and fluoride ions.

A study published earlier this month by environmental scientists at Stockholm University and ETH Zurich found that rainfall samples from around the world exceeded the latest guidelines from the US Environmental Protection Agency for PFAS levels in drinking water.

Based on these guidelines, “rainwater everywhere would be judged unsafe to drink”, said Ian Cousins of Stockholm University. “Although in the industrial world we don’t often drink rainwater, many people around the world expect it to be safe to drink and it supplies many of our drinking water sources.”

Water companies can filter PFAS out of drinking water but the chemicals then need to be disposed of — and the only methods available today involve high temperatures or pressures. Incineration may release some PFAS into the air, said Dichtel, while burying them in landfills is “just guaranteeing that you will have a problem 30 years from now because it’s going to slowly leach out”.

The Northwestern-UCLA process will also need PFAS to be captured or concentrated from water and contaminated sites before they can be destroyed. The scientists behind the discovery said they are ready to work with the environmental remediation industry to apply the approach while they work to extend their strategy to other types of forever chemicals.