Question 1

What is 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic Acid?

Accepted Answer

9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic Acid (9Cl-PF3ONS) 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 9Cl-PF3ONS in my drinking water?

Accepted Answer

EPA UCMR5 testing (2023-2025) monitors 9Cl-PF3ONS at 6,800+ US water systems. Enter your ZIP code at KnowYourExposure.com to see if 9Cl-PF3ONS has been detected in your specific utility.

Question 3

What is the EPA limit for 9Cl-PF3ONS?

Accepted Answer

Not all PFAS compounds have federal limits yet. The EPA's 2024 PFAS Rule set limits for 6 compounds including PFOA, PFOS, PFHxS, PFNA, and HFPO-DA. Others are still under review.

Question 4

What are the health effects of 9Cl-PF3ONS?

Accepted Answer

9Cl-PF3ONS exposure has been linked to: Unknown long-term effects; monitoring ongoing. Long-term exposure increases risks even at low doses.

Question 5

How do I remove 9Cl-PF3ONS from my water?

Accepted Answer

Certified reverse osmosis systems remove 90%+ of most PFAS including 9Cl-PF3ONS. Activated carbon and ion exchange filters also work. Boiling does NOT remove PFAS – it concentrates them.

Question 6

What is the CAS number for 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic Acid?

Accepted Answer

The CAS Registry Number for 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic Acid is 756426-58-1.

9Cl-PF3ONS: Health Effects, EPA Limits & Sources (2026)