Q. Why is this in News?
A. According to a recent study, scientists have found that rainwater from many places across the globe is contaminated with Per- and Polyfluoroalkyl Substances (PFAs).
- Further, they are called Forever chemicals because of their tendency to stick around in the atmosphere, rainwater, and soil for long periods of time.
- PFAs are also listed in the Stockholm Convention.
Q. What is Stockholm Convention?
- It is a global treaty to protect human health and the environment from persistent organic pollutants (POPs). POPs are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of living organisms and are toxic to humans and wildlife.
- Support the transition to safer alternatives.
- Target additional POPs for action.
- Clean up old stockpiles and equipment containing POPs.
- Work together for a POPs-free future.
- India ratified the Stockholm Convention in 2006 as per Article 25(4), which enabled it to keep itself in a default "opt-out" position such that amendments in various Annexes of the convention cannot be enforced on it unless an instrument of ratification/ acceptance/ approval or accession is explicitly deposited with UN depositary.
Q. What are Per- and Polyfluoroalkyl Substances (PFAs)?
- They 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.
- They can migrate to the soil, water, and air during their production and use.
- Most PFAs do not break down, they remain in the environment for long periods of time.
- Further, some of these PFAs can build up in people and animals if they are repeatedly exposed to the chemicals.
- Harmful Effects:
- They cause 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.
Q. What can be done to Remove these Chemicals?
- 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 foams.
- 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 around 1,500 degrees Celsius (2,730 degrees Fahrenheit), but it’s energy intensive and suitable incinerators are scarce.
- Supercritical Water Oxidation:
- Scientists have developed supercritical water oxidation to destroy PFAS.
- High temperatures and pressures change the state of water, accelerating chemistry in a way that can destroy hazardous substances.
- Plasma Reactors:
- Researchers are working with plasma reactors, which use water, electricity, and argon gas to break down PFAS.
- Filtration System:
- Filtration system can be used with activated carbon in the rain water harvesting system.
- The activated carbon will need to be removed and replaced regularly. Also, the old contaminated material must be destroyed.
- There are several other experimental techniques that are promising but haven’t been scaled up to treat large amounts of the chemicals.