GenX (HFPO-DA)

GenX (also known as HFPO-DA) is a PFAS chemical developed by Chemours (a DuPont spinoff) as a replacement for PFOA in the manufacture of fluoropolymers. It was marketed as a safer alternative, but research shows it is also persistent in the environment and potentially toxic.

The EPA set a Maximum Contaminant Level of 10 parts per trillion (ppt) for GenX in 2024, recognizing that this replacement chemical poses its own health risks.

Why Is GenX a Concern?

While GenX has a shorter half-life in the body than PFOA (days vs. years), animal studies conducted by the EPA and independent researchers have raised significant concerns:

• Liver toxicity, including liver tumors in chronic animal studies
• Kidney effects and potential kidney cancer
• Immune system suppression
• Developmental effects in offspring, including reduced bone growth
• Pancreatic and testicular effects

GenX is also highly mobile in water — it passes through conventional water treatment processes more easily than longer-chain PFAS like PFOA and PFOS, making it particularly challenging for water utilities.

How Does GenX Enter Drinking Water?

GenX contamination is primarily linked to chemical manufacturing facilities that produce fluoropolymers. The most notable contamination occurred near the Chemours Fayetteville Works plant in North Carolina, which discharged GenX into the Cape Fear River for years before it was detected in 2017. The contamination affected drinking water for over 300,000 people in the Wilmington, NC area.

GenX can also form as a byproduct of water treatment processes that break down other PFAS, and it has been detected in rainwater globally.

GenX vs. Other PFAS

GenX was specifically designed as a "safer" replacement for PFOA, but it represents a common pattern where replacement chemicals turn out to have their own risks — sometimes called "regrettable substitution." GenX is regulated under the EPA's Hazard Index alongside PFHxS, PFNA, and PFBS.

How to Remove GenX From Your Water

• Reverse Osmosis: The most effective home treatment, removing 90%+ of GenX. Under-sink systems typically cost $150-$500.
• Granular Activated Carbon: Less effective for GenX than for PFOA/PFOS due to GenX's shorter chain length. Requires more frequent filter changes.
• Ion Exchange: Can be effective in specialized configurations, but not all ion exchange systems target GenX.

For GenX specifically, reverse osmosis is the recommended approach. Standard activated carbon may not provide adequate removal.