So-called permanent chemicals in everyday items like nonstick frying pans have long been linked to serious health problems, and now scientists say they have figured out how to combat them.
Chemists from the United States and China announced Thursday that they had discovered an innovative method to degrade these contaminating compounds, known as PFAS, using relatively low temperatures and common reagents.
The results of their research were published in the journal Science and may represent a solution to a permanent source of damage to the environment, livestock and humans.
“That’s really why I do science, to have a positive impact on the world,” lead author William Dichtel of Northwestern University told reporters at a press conference.
PFAS, or perfluoroalkyl and polyfluoroalkyl substances, were first developed in the 1940s and are now present in a variety of products including nonstick skillets, waterproof textiles and fire extinguishing foams.
Over time, contaminants have spread and accumulated in the environment, penetrating the air, soil, groundwater, lakes and rivers as a result of industrial processes and degradation in landfills.
A study published last week by scientists at Stockholm University demonstrated that rainwater across the planet is unsafe to drink due to PFAS contamination.
Chronic exposure—even at low levels—has been linked to liver damage, high cholesterol, poor immune response, low birth weight and various types of cancer.
While PFAS chemicals can be filtered out of the water, there are few solutions to dispose of them once they are out.
Ten minus, thousands to go
Current methods to destroy PFAS require intensive treatments, such as incineration at extremely high temperatures or irradiation with ultrasonic waves. The indestructibility of PFAS is due to their carbon fluoride bonds, one of the strongest in organic chemistry.
Fluorine is the most electronegative element and accumulates electrons, while carbon seeks to share them. PFAS molecules contain long chains of these bonds, but the scientists found a weak spot.
At one end of the molecule are oxygen atoms that can be attacked with a solvent and a common reagent at temperatures of 80 to 120 degrees Celsius, thus decapitating the head of the molecular group and leaving a reactive tail.
A second part of the study focused on using powerful computational methods to map the quantum mechanics behind the chemical reactions the team performed to destroy the molecules.
“When this occurs, you access previously unrecognized pathways, which cause the entire molecule to disintegrate in a series of complex reactions,” said Dichtel, which ultimately render the end products benign. The new procedure could eventually lead to improvements in the method of destruction.
The current study focused on ten PFAS chemicals, including a contaminant called GenX, which contaminated the Cape Fear River in North Carolina.
But that’s just the tip of the iceberg, as the US Environmental Protection Agency has identified more than 12,000 PFAS chemicals. “There are other classes that don’t have the same Achilles heel, but each one will have its own fragility. If we can identify it, then we will know how to activate it to destroy it”, said Dichtel.
