Blog Post by: Karun Tyagi

In recent years, sustainability and regulatory concerns have led to a shift from C8 to C6 chemistries in textile water-repellent finishes. These changes aim to reduce environmental impact and health risks, particularly those associated with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). However, one key question often arises: can PFOA and PFOS be found in textiles treated with C6 chemistries? Let’s explore this in detail.

Understanding C6 and C8 Chemistries

C8 Chemistry

• Structure: Contains eight carbon atoms in the fluorinated chain.
• Degradation Products: Degrades into long-chain perfluoroalkyl substances (PFAS), primarily PFOA and PFOS.
• Environmental Concerns: Highly persistent, bioaccumulative, and toxic.

Chemical Formula of PFOA: C8HF15O2

Chemical Formula of PFOS: C8HF17O3S

C6 Chemistry

• Structure: Composed of six carbon atoms in the fluorinated chain.
• Degradation Products: Breaks down into perfluorohexanoic acid (PFHxA) and other short-chain PFAS.
• Environmental Profile: Reduced persistence and toxicity compared to C8 compounds.

Chemical Formula of PFHxA: C6HF11O2

Pros and Cons of C8 and C6 Chemistries

C8 Chemistry

Pros:

Superior Performance:

• Offers excellent water, oil, and stain repellency.
• More effective at repelling a wide range of contaminants compared to C6.

Durability:

• Long-lasting performance across multiple washes and wear cycles.

Cons:

Environmental Impact:

• Degrades into PFOA and PFOS, which are highly persistent and bioaccumulative.
• Associated with severe environmental and health risks.

Regulatory Restrictions:

• Banned or severely restricted in many regions due to toxicity concerns.

EHS Concerns:

• Classified as toxic and potentially carcinogenic.

C6 Chemistry

Pros:

Reduced Environmental Impact:

• Degrades into shorter-chain PFAS (e.g., PFHxA), which are less toxic and persistent.

Regulatory Compliance:

• Meets global environmental and health safety standards, making it suitable for use in regulated markets.

Safety:

• Lower toxicity and bioaccumulation potential compared to C8 chemistries.

Cons:

Performance Limitations:

• Less effective at repelling oil and stains compared to C8.
• May require additional formulations to achieve comparable results.

Durability:

Slightly lower durability across multiple washes and extended use.

Can C6 Chemistries Produce PFOA or PFOS?

The simple answer is no. Here’s why:

1. Chemical Structure: C6-based products lack the eight-carbon chain structure necessary to produce PFOA or PFOS. The degradation of these products results in shorter-chain PFAS, such as PFHxA, rather than long-chain compounds.
2. Degradation Pathways: C6 compounds degrade via specific pathways that do not involve the formation of C8-related substances. For example, perfluorohexane sulfonic acid (PFHxS) or its precursors break down into PFHxA, which has a distinct chemical profile.
3. Regulatory and Analytical Data: Studies on C6-treated textiles show no direct formation of PFOA or PFOS. Regulatory bodies focus on monitoring short-chain degradation products (e.g., PFHxA) when assessing C6 finishes.

C8 Compounds –> PFOA, PFOS (Persistent, Long-Chain PFAS)

C6 Compounds –> PFHxA (Short-Chain PFAS, Less Persistent)

Why Might PFOA or PFOS Be Found in C6-Treated Products?

If PFOA or PFOS are detected in a product marketed as using C6 chemistry, the likely causes are:

1. Shared Manufacturing Equipment: In facilities where both C6 and C8 chemistries are handled, the same machinery may be used for production. Residual traces of C8 chemicals left in equipment, pipes, or containers can inadvertently mix with C6 formulations. Even small quantities of contamination can result in detectable levels of PFOA or PFOS in finished products.
2. Raw Material Impurities: Some raw materials sourced for C6 formulations may be contaminated with trace amounts of C8 compounds. This contamination could occur during raw material production, transportation, or storage.
3. Environmental Exposure: Storage or handling of C6-treated textiles in areas exposed to C8-treated products can lead to cross-contamination. For example, aerosols from C8 formulations used nearby could settle on C6-treated textiles.
4. Human Error: Mistakes during production, such as mislabeling of chemicals or accidental mixing of C8 with C6 formulations, can introduce contamination.

How to Ensure Compliance?

Manufacturers aiming to produce PFOA- and PFOS-free textiles using C6 chemistries can follow these steps:

1. Strict Supply Chain Control: Verify that all raw materials are free from C8 compounds and meet regulatory requirements.
2. Dedicated Equipment: Use separate equipment for C6 and C8 formulations or implement rigorous cleaning protocols.
3. Regular Testing: Conduct periodic tests for residual PFOA and PFOS in both raw materials and finished products to ensure compliance.

Conclusion

C6 chemistries were developed to provide effective water repellency with a significantly reduced environmental footprint compared to C8 chemistries. These formulations do not produce PFOA or PFOS under normal degradation processes. However, manufacturers must remain vigilant about cross-contamination and raw material integrity to ensure compliance with global regulatory standards.

By understanding the chemistry and following best practices, the textile industry can confidently embrace safer, environmentally friendlier solutions without compromising performance.

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