For Prelims: Per- and Polyfluoroalkyl Substances (PFAs), Forever chemicals, Incineration, Supercritical Water Oxidation, Plasma Reactors

For mains: Environmental Pollutants' Effects on the Human Body; Economic Significance of Chemicals; and Process of Water Oxidation; Harmful Effects on Human Health

Why in the news?

According to a recent study published in Environment Science and Technology, "per- and polyfluoroalkyl substances" (PFAs), also known as "forever chemicals,"

It has a tendency to persist in the atmosphere, rainwater, and soil for extended periods of time, contaminating rainwater from many locations around the world.

What do we need to know about PFAs?

About

For a reason, PFAS, a class of manufactured chemicals that have been extensively used since the 1940s, is referred to as "forever chemicals." 

They cannot be consumed by bacteria, burned by fire, or diluted by water.  Additionally, if these dangerous substances are buried, they seep into the soil and persist for future generations.

PFAS contains a long tail of unyielding carbon-fluorine bonds. But at one end of the molecule, there is a charged group that often contains charged oxygen atoms.

  • The US Centers for Disease Control and Prevention (CDC) describes PFAs as synthetic chemicals used to create nonstick cookware, clothing that repels water and oil, fabrics that resist stains, cosmetics, firefighting gear, and numerous other products. During the course of their creation and use, PFAs can migrate to the soil, water, and air. The majority of PFAs do not degrade, so they linger in the environment for a long time.
  • If people and animals are exposed to these PFAs on a regular basis, they may develop an accumulation of the chemicals.
  • Reduced fertility is one of the health risks associated with PFA exposure that the United States Environmental Protection Agency (EPA) lists. 

Negative effects of PFAs

They cause a variety of health risks that are attributed to PFA exposure, including

  • Decline in fertility
  • Effects on a child's development
  • Interfere with bodily hormones, 
  • Higher levels of cholesterol
  • Elevated risk of certain cancers.
  • Additionally, recent studies have shown that long-term low-level exposure to some PFAs can interfere with the ability of people to produce antibodies in response to vaccination against a variety of diseases.

How can these chemicals be removed from rainwater?

  • While there is no known method that can extract and remove PFAs from the atmosphere itself, there are many effective, albeit expensive, methods to remove them from rainwater that has been collected through various rainwater harvesting methods.
  • One way to do this would be to use a filtration system with activated carbon. The activated carbon will need to be removed and replaced regularly. Also, the old contaminated material must be destroyed.
  • Filtration System:
    • In the rainwater harvesting system, the filtration system can be combined with activated carbon.
      • It will be necessary to regularly remove and replace the activated carbon. Additionally, the outdated, contaminated material needs to be destroyed.
  • Incineration:
    • The most common method of destroying PFAS is incineration, but most PFAS are remarkably resistant to being burned. That’s why they’re used in firefighting foam.
    • PFAS has multiple fluorine atoms attached to a carbon atom, and the bond between carbon and fluorine is one of the strongest.
    • Normally to burn something, you have to break the bond, but fluorine resists breaking off from carbon.
    • Most PFAS will break down completely at incineration temperatures of around 1,500 degrees Celsius (2,730 degrees Fahrenheit), but it’s energy intensive and suitable incinerators are scarce.
  • Supercritical Water Oxidation:
    • For the purpose of removing PFAS, scientists have created supercritical water oxidation.
      • High pressures and temperatures alter the nature of water, accelerating chemistry in a way that can degrade potentially dangerous substances.
  • Plasma Reactors:
    • In order to break down PFAS, scientists are using plasma reactors, which combine argon gas, electricity, and water.
  • Ten perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl ether carboxylic acids (PFECAs), including perfluorooctanoic acid (PFOA) and one of its common replacements, known as GenX — two of the most well-known PFAS compounds — are also the subject of additional experiments.