University of California, Riverside researchers have identified the chemical reactions that occur when ultraviolet light destroys PFAS, or "forever chemicals," in water, potentially paving the way for more effective treatment technologies that could reduce contamination in food and drinking water. The study, published in Nature Water, reveals how UV light combined with sulfite can break apart the extremely stable carbon-fluorine bonds that make PFAS so difficult to eliminate from the environment.

What Are PFAS and Why Should You Care?

Per- and polyfluoroalkyl substances, commonly called PFAS, are a large family of synthetic chemicals that have been used since the 1940s in countless industrial and consumer products. You've likely encountered them in nonstick cookware, food packaging, water-resistant textiles, and firefighting foams. The problem is that these chemicals don't break down naturally, earning them the nickname "forever chemicals" because they persist indefinitely in the environment and in your body.

Once PFAS enter the environment, they accumulate in surface water, groundwater, soil, and air, eventually contaminating crops, livestock, and drinking water supplies. This means exposure to PFAS is nearly unavoidable for most people. Research has linked exposure to certain PFAS with higher cholesterol levels, increased cancer risk, developmental complications in children, liver damage, and weakened immune system function.

How Does UV Light Destroy These Stubborn Chemicals?

The UCR research team identified a complex sequence of chemical reactions that allows UV light to dismantle PFAS molecules. When UV light and sulfite work together, they generate highly reactive electrons that attack PFAS molecules and initiate the breakdown of their carbon-fluorine bonds. As these bonds break, fluorine atoms are stripped from the molecules and released into the water as fluoride ions. Hydroxyl radicals and hydroxide ions also participate in the process, breaking carbon-carbon bonds and fragmenting the remaining molecular chains.

The resulting shorter-chain compounds undergo further defluorination, progressively dismantling the PFAS molecules and releasing additional fluoride. This step-by-step breakdown is crucial because it means the chemicals can be more completely destroyed rather than simply converted into other harmful compounds.

"Knowing this degradation mechanism gives us a better understanding of how to optimize the conditions for PFAS destruction and achieve deeper degradation and gives us a much better roadmap for improving the technology," said Jinyong Liu, Associate Professor of Chemical and Environmental Engineering at UCR and the study's corresponding author.

Jinyong Liu, Associate Professor of Chemical and Environmental Engineering at University of California, Riverside

How Could This Research Improve Food Safety?

The implications of this research extend far beyond laboratory settings. Understanding exactly how PFAS molecules break down under UV treatment allows scientists and engineers to optimize water treatment systems, potentially removing more PFAS from drinking water supplies and reducing contamination in food production. The findings could help determine which treatment technologies, combinations of technologies, and operating conditions achieve the most complete PFAS destruction.

Additionally, the research corrected degradation mechanisms reported in earlier scientific literature that had been based largely on assumptions rather than experimental evidence. This correction is important because it ensures that future treatment systems are designed based on accurate chemistry rather than incomplete understanding.

Steps to Reduce Your PFAS Exposure

• Cookware Choices: Replace nonstick cookware with stainless steel, cast iron, or ceramic alternatives that don't contain PFAS-based coatings, which can leach into food during cooking.
• Food Packaging: Avoid storing fatty foods in paper or cardboard packaging treated with water-resistant coatings, as PFAS migrate more readily into fatty substances; use glass or stainless steel containers instead.
• Water Filtration: Consider using a water filter certified to remove PFAS, particularly if you live near industrial areas, airports, or military bases where PFAS contamination is more common.
• Limit Processed Foods: Reduce consumption of highly processed foods that may come in PFAS-treated packaging, focusing instead on whole foods stored in minimal packaging.

What's Next for PFAS Treatment Technology?

The UCR findings open another important avenue for progress: designing better fluorinated compounds from the start. By understanding the degradation mechanisms, researchers can provide guidance to the fluorocarbon industry on how to create compounds that break down more easily after use, preventing PFAS accumulation in the environment in the first place.

This proactive approach represents a shift from simply cleaning up PFAS contamination to preventing it at the source. As regulatory agencies and manufacturers grapple with PFAS contamination in food and water supplies, this research provides a scientific foundation for developing more effective treatment technologies and designing safer alternatives to these persistent chemicals.