Context
- A recent study published in the Proceedings of the National Academy of Sciences (PNAS) found that exposure to PFOS, a widespread “forever chemical”, can weaken the body’s natural defence against viral infections.
- Researchers found that PFOS interferes with IRF3, a key immune protein, reducing the production of antiviral type-I interferons and weakening the body’s early response to viruses.
About PFOS
- Perfluorooctane sulfonic acid (PFOS) and its salts are highly fluorinated synthetic chemicals belonging to the broader family of per- and polyfluoroalkyl substances (PFAS).
- PFOS contains an eight-carbon fluorinated chain associated with a sulfonic acid/sulfonate group.
- Its exceptionally strong carbon-fluorine bonds make it highly resistant to heat, chemical reactions and environmental degradation.
- This extreme persistence is why PFOS and many other PFAS are commonly called “forever chemicals.”
What Did the Recent Study Find?
- Immune interference: PFOS can interact with Interferon Regulatory Factor 3 (IRF3), an important protein involved in the body’s innate antiviral response.
- Reduced antiviral defense: Interference with IRF3 reduces production of type-I interferons, signaling proteins that help cells restrict viral replication.
- Experimental evidence: Laboratory and animal experiments showed that PFOS exposure could weaken antiviral defence and facilitate viral replication.
- Human evidence: Higher PFOS levels were associated with higher viral loads among patients with influenza, respiratory syncytial virus (RSV) and hepatitis B. This association does not by itself establish causation.
Thus, the study provides a possible biological mechanism linking environmental PFOS exposure with impaired antiviral immunity.
Why is PFOS an Environmental and Health Concern?
- Persistence: PFOS breaks down extremely slowly, allowing contamination to remain for long periods.
- Mobility: It can move through soil and groundwater, spreading beyond its original source.
- Bioaccumulation: PFOS can accumulate in living organisms and become concentrated through aquatic food chains, including in fish consumed by humans.
- Health effects: Scientific evidence indicates that sufficient PFOS exposure can adversely affect the immune system, liver, cardiovascular system and development.
Major Uses and Sources
- PFOS has historically been used for its water-, oil-, grease- and stain-resistant properties in textiles, carpets, leather products, surface treatments and industrial applications.
- It has also been used in certain firefighting foams, particularly at airports, military facilities and fire-training sites.
- Because of its persistence, legacy contamination may remain even after particular uses have been restricted or discontinued.
Global Regulation
- PFOS, its salts and perfluorooctane sulfonyl fluoride (PFOSF) were listed under the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2009.
- They are listed under Annex B (Restriction), which restricts their production and use while allowing specified acceptable purposes or exemptions.
PFOS vs PFAS
- PFAS is the broader family of highly fluorinated chemicals, while PFOS is one member of this family.
- Other important PFAS include PFOA (Perfluorooctanoic Acid) and PFHxS (Perfluorohexane Sulfonic Acid).
FAQs
Q1. What is PFOS?
PFOS is a highly persistent synthetic PFAS chemical associated with several historical industrial and consumer uses.
Q2. Why is PFOS called a “forever chemical”?
Its strong carbon-fluorine bonds make it extremely resistant to environmental degradation.
Q3. How can PFOS weaken antiviral immunity?
It can interfere with IRF3, reducing the type-I interferon response needed to restrict viral replication.
Q4. Is PFOS the same as PFAS?
No. PFAS is the broader chemical family, while PFOS is one member of that family.
Q5. Under which Stockholm Convention Annex is PFOS listed?
PFOS, its salts and PFOSF are listed under Annex B (Restriction).
