Perfluorohexane Sulfonic Acid (PFHxS)
Perfluorohexane sulfonic acid (PFHxS) is a 6-carbon sulfonated PFAS that emerged as a replacement for PFOS following its phase-out. Like PFOS, PFHxS is found extensively at military bases and airports where firefighting foam was used. Despite being shorter-chain, PFHxS has a surprisingly long biological half-life of approximately 8 years in humans–longer even than PFOA or PFOS. This persistence makes it particularly concerning from a public health standpoint. PFHxS is included in the 2024 EPA "hazard index" regulation alongside PFNA, HFPO-DA, and PFBS.
Where PFHxS comes from
Common uses
- Firefighting foam replacement
- Aqueous film-forming foam
- Carpet and fabric protection
- Industrial surfactants
Industries
- Firefighting
- Textiles
- Industrial chemicals
Health effects of PFHxS exposure
Short-term effects
- Thyroid disruption
Long-term effects
- Thyroid disease
- Neurodevelopmental effects
- Immune suppression
- Liver damage
- Reproductive harm
Most vulnerable populations
- Children (neurodevelopmental risk)
- People with thyroid disorders
- Military personnel
How to remove PFHxS from drinking water
- Reverse osmosis
- 90% removal
- Activated carbon
- 72% removal
- Ion exchange
- 92% removal
Is PFHxS in your water? – Enter your ZIP at KnowYourExposure to see your local EPA test results.