In August 2022, researchers from the United States Environmental Protection Agency (EPA), led by William Dichtel and Brittany Trang, submitted a report in the journal Science stating that they have found a breakthrough method to degrade the polluting compounds called per-and polyfluoroalkyl substances (PFASs). This finding would address widespread environmental contamination across the world.
What are PFASs?
According to the US Centre for Disease Control and Prevention (CDC), PFASs are man-made chemicals that are used to make non-stick cookware, water-repellent clothing, stain-resistant fabrics, cosmetics, firefighting foams, etc. First developed in the 1940s, PFASs are used to make many other products that resist grease, water, and oil. PFASs are called ‘forever chemicals’ as they do not naturally break down. These chemicals prevent corrosion, and make products waterproof and stain-resistant, due to which they are extensively used in paints, varnishes, sealants, etc.
Contamination by PFASs
Man-made processes that attempt to destroy PFASs/forever chemicals are expensive and energy intensive. Destroying them requires harsh treatments like incineration at extremely high temperatures or irradiating them with ultrasonic waves. They are virtually indestructible because of their carbon-fluorine bonds which are one of the strongest types of bonds in organic chemistry. PFASs have the ability to migrate into the soil, water, and air, during their production and use. As PFASs do not degrade, they steadily get accumulated and contaminate the environment. Stockholm University scientists, in their study, have found that rainwater everywhere on the planet is unsafe to drink because of PFAS contamination. They have been detected in the Arctic as well. Some of the PFASs could build up in people and animals if they are repeatedly exposed to the chemicals.
Human exposure to PFASs is widespread. People get exposed to these chemicals mainly from drinking contaminated water, eating food packaged in certain materials, or using products embedded with PFASs. There are a variety of health risks that are attributed to PFAS exposure in humans, including decreased fertility, developmental effects in children, interference with body hormones, increased cholesterol levels, and increased risk of some cancers. Recent research has also revealed that long-term low-level exposure to certain PFASs could make it difficult for humans to build antibodies even after being vaccinated against various diseases.
Despite reduced use of PFASs, about 97 per cent Americans are contaminated with these ‘forever chemicals’. In Lyon, France, mothers have been found potentially toxic with PFASs. This has made unborn children particularly vulnerable to infection as PFASs can also enter the placenta and reach the blood of the foetus.
Findings of the Study
The researchers from the Northwestern University of California at Los Angeles, and Tianjin University, China, have found a way to decompose PFASs using inexpensive reagents at a relatively low temperature. There are about 12,000 compounds that comprise the PFAS class. The recent findings are effective on one sub-class—the perfluorocarboxylic acids including compounds commonly found in the environment, such as perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA). These chemicals are highly toxic even at low levels, and have been used in products such as waxes and food packaging.
These findings to break down PFASs are preliminary, and the method cannot be applied on a commercial level. The researchers first placed a PFAS compound in a solvent called dimethyl sulfoxide (DMSO). It was then mixed with sodium hydroxide or lye (NaOH) in water. The researchers found that when this mixture was heated up to a boiling temperature, the PFA compound began to degrade. However, this method of break-down of PFASs only worked for certain PFASs.
The scientists are now looking at ways to scale up their technique to include different types, and also, large amounts of PFASs.
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