Perfluorooctane Sulfonic Acid (PFOS)
Perfluorooctane sulfonic acid (PFOS) is the most widely detected PFAS in human blood samples globally. Produced primarily by 3M under the brand name Scotchgard, PFOS was used extensively in firefighting foam (AFFF), carpet protectors, and industrial processes. Its 8-carbon chain makes it particularly persistent and bioaccumulative. The US phased out PFOS production in 2002, but military bases, airports, and industrial sites where AFFF was used remain significant contamination sources. PFOS is listed under the Stockholm Convention as a persistent organic pollutant. The 2024 EPA maximum contaminant level of 4 ppt applies to both PFOA and PFOS individually.
Where PFOS comes from
Common uses
- Aqueous film-forming foam (AFFF)
- Carpet and upholstery protectants (Scotchgard)
- Paper food packaging
- Metal plating
- Semiconductor etching
Industries
- Firefighting
- Military
- Textiles
- Electronics
- Manufacturing
Health effects of PFOS exposure
Short-term effects
- Liver toxicity at high doses
- Hormonal disruption
Long-term effects
- Bladder cancer
- Kidney cancer
- Non-Hodgkin lymphoma
- Thyroid disorders
- Reproductive harm
- Developmental delays in children
- Elevated cholesterol
- Immune suppression
Most vulnerable populations
- Military veterans (base contamination)
- Children and adolescents
- Pregnant and breastfeeding women
- People near airports and fire training facilities
How to remove PFOS from drinking water
- Reverse osmosis
- 96% removal
- Activated carbon
- 85% removal
- Ion exchange
- 96% removal
Stricter state limits
- New Jersey
- 13 ppt
- Massachusetts
- 20 ppt
- Michigan
- 8 ppt
- New York
- 10 ppt
Is PFOS in your water? – Enter your ZIP at KnowYourExposure to see your local EPA test results.