Perfluorooctane Sulfonamide (PFOSA)

Perfluorooctane sulfonamide (PFOSA) is a precursor compound that degrades to PFOS in the environment. It was used in the production of Scotchgard and other PFAS-based products. PFOSA is listed as a PFOS precursor under Stockholm Convention restrictions. When released into the environment, PFOSA converts to PFOS over time, effectively contributing to PFOS contamination in water supplies. PFOSA itself has been found in human blood samples, particularly in workers who handled PFAS products. Its detection in drinking water often indicates the presence of more PFOS than direct testing would reveal.

Where PFOSA comes from

Common uses

  • Precursor to PFOS in manufacturing
  • Firefighting foam components
  • Carpet and textile treatments

Industries

  • Chemical manufacturing
  • Firefighting
  • Textiles

Health effects of PFOSA exposure

Short-term effects

  • Neurotoxicity at high doses
  • Liver effects

Long-term effects

  • Converts to PFOS–carries same long-term risks
  • Neurotoxicity
  • Liver damage
  • Immune suppression

Most vulnerable populations

  • Occupationally exposed workers
  • People near PFOS contamination sites

How to remove PFOSA from drinking water

Reverse osmosis
94% removal
Activated carbon
82% removal
Ion exchange
94% removal

See filters certified to remove PFOSA and other PFAS.

Is PFOSA in your water?Enter your ZIP at KnowYourExposure to see your local EPA test results.