Question 1

What is Hexafluoropropylene Oxide Dimer Acid (GenX)?

Accepted Answer

Hexafluoropropylene Oxide Dimer Acid (GenX) (HFPO-DA) is a per- and polyfluoroalkyl substance (PFAS) – a synthetic chemical used in manufacturing, firefighting foam, and consumer products. It persists indefinitely in water and the human body.

Question 2

Is HFPO-DA in my drinking water?

Accepted Answer

EPA UCMR5 testing (2023-2025) monitors HFPO-DA at 6,800+ US water systems. Enter your ZIP code at KnowYourExposure.com to see if HFPO-DA has been detected in your specific utility.

Question 3

What is the EPA limit for HFPO-DA?

Accepted Answer

The EPA drinking water limit for HFPO-DA is 10 parts per trillion (ppt). Utilities have until 2029 to reduce levels below this threshold under the 2024 PFAS Rule.

Question 4

What are the health effects of HFPO-DA?

Accepted Answer

HFPO-DA exposure has been linked to: Liver cancer (in animal studies), Kidney tumors (in animal studies), Immune suppression. Long-term exposure increases risks even at low doses.

Question 5

How do I remove HFPO-DA from my water?

Accepted Answer

Certified reverse osmosis systems remove 90%+ of most PFAS including HFPO-DA. Activated carbon and ion exchange filters also work. Boiling does NOT remove PFAS – it concentrates them.

Question 6

What is the CAS number for Hexafluoropropylene Oxide Dimer Acid (GenX)?

Accepted Answer

The CAS Registry Number for Hexafluoropropylene Oxide Dimer Acid (GenX) is 13252-13-6.

HFPO-DA: Health Effects, EPA Limits & Sources (2026)