Scientists Find 'Forever Chemicals' Have a Hidden Weakness: Hydrogen Radicals and UV Light

Scientists have identified an unexpected weak point in some of the most stubborn pollutants on Earth. A new study finds that hydrogen radicals, generated by intense ultraviolet light, can break down PFAS "forever chemicals" without the need for added reagents — pointing toward a cleaner way to destroy the compounds rather than merely trapping them.

PFAS, short for per- and polyfluoroalkyl substances, are a family of thousands of synthetic chemicals used since the mid-20th century in nonstick cookware, water-repellent fabrics, firefighting foams and food packaging. Their durability comes from carbon-fluorine bonds, among the strongest in chemistry, which is exactly why they resist breaking down in the environment and accumulate in soil, water and human blood, where they have been linked to a range of health concerns.

The researchers found that hydrogen radicals — extremely reactive fragments produced when high-energy UV light strikes water — attack PFAS molecules directly, gradually stripping away fluorine atoms and cleaving the molecules into smaller, less persistent compounds. The process proved most effective under high-energy UV light at wavelengths below 300 nanometers. By pinpointing hydrogen radicals as the key actor, the team gained a much clearer picture of the chemical reactions driving the breakdown.

The finding challenges earlier assumptions about how PFAS degrade. Previous studies had suggested that other reactive species were chiefly responsible for tearing the molecules apart. By showing that hydrogen radicals play the dominant role, the new work offers a sharper blueprint for engineers designing treatment systems that actually destroy the chemicals instead of filtering and concentrating them for disposal.

The study, titled "Mechanistic Insights into Per- and Polyfluoroalkyl Substance (PFAS) Photolysis under Intensified Simulated Solar Light," was published in the journal Environmental Science & Technology. With regulators around the world tightening limits on PFAS in drinking water, a method that breaks the toughest carbon-fluorine bonds using little more than light and water could prove a valuable tool — though scaling the approach from the laboratory to municipal treatment plants remains a significant challenge.