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Forever Chemicals: Contaminating Rainwater


A recent study published in Environment Science and Technology has found that rainwater from many places across the globe is contaminated with “per- and polyfluoroalkyl substances,” (PFAs), which are called “forever chemicals” because of their tendency to stick around in the atmosphere, rainwater and soil for long periods of time.


GS Paper 3: Conservation, environmental pollution and degradation, environmental impact assessment

Mains Question

Investigate the causes of high levels of pollution in Indian rivers. What can be done to keep our rivers from deteriorating and dying slowly? Discuss. (250 words)

What are PFAs?

  • According to the US Centre for Disease Control and Prevention (CDC), PFAs are man-made chemicals used to make nonstick cookware, water-repellent clothing, stain-resistant fabrics, cosmetics, firefighting forms and many other products that resist grease, water and oil.
  • PFAs can migrate to the soil, water and air during their production and use. Since most PFAs do not break down, they remain in the environment for long periods of time.
  • Some of these PFAs can build up in people and animals if they are repeatedly exposed to the chemicals.

What harm do PFAs cause?

  • The United States Environmental Protection Agency (EPA) lists a variety of health risks that are attributed to PFA exposure, 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 PFAs can make it difficult for humans to build antibodies after being vaccinated against various diseases.

Do we need to be worried about PFAs in the rainwater in India?

While the recently published research article did not include studies of samples collected in India, the nature of PFAs and the wide geographical breadth of samples and the nature of PFAs means that the results can be extrapolated to India, according to lead author Ian Cousins, who spoke to over an email interaction regarding the same.

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.
  • The researchers first placed a PFA compound in a solvent called DMSO (dimethyl sulfoxide). They then mixed it with sodium hydroxide (lye) in water.
  • They found that when this mixture was heated up to boiling temperature, the PFA compound began to degrade.
  • However, this method doesn’t work for all PFAs and only works for certain PFA subsets

November 2023