Question 1

What is 4:2 Fluorotelomer Sulfonate?

Accepted Answer

4:2 Fluorotelomer Sulfonate (4:2 FTS) 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 4:2 FTS in my drinking water?

Accepted Answer

EPA UCMR5 testing (2023-2025) monitors 4:2 FTS at 6,800+ US water systems. Enter your ZIP code at KnowYourExposure.com to see if 4:2 FTS has been detected in your specific utility.

Question 3

What is the EPA limit for 4:2 FTS?

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 4:2 FTS?

Accepted Answer

4:2 FTS exposure has been linked to: Degrades to PFBA and other PFAS; indirect exposure risk, Environmental persistence. Long-term exposure increases risks even at low doses.

Question 5

How do I remove 4:2 FTS from my water?

Accepted Answer

Certified reverse osmosis systems remove 90%+ of most PFAS including 4:2 FTS. Activated carbon and ion exchange filters also work. Boiling does NOT remove PFAS – it concentrates them.

Question 6

What is the CAS number for 4:2 Fluorotelomer Sulfonate?

Accepted Answer

The CAS Registry Number for 4:2 Fluorotelomer Sulfonate is 757124-72-4.

4:2 FTS: Health Effects, EPA Limits & Sources (2026)