5:3 fluorotelomer carboxylic acid (5:3 FTCA)

At a glance

Regulatory & certification status

Where 5:3 FTCA stands across the major regulatory systems and the certifications a bedroom product might carry. Because this compound is not individually classified anywhere, most rows state plainly that no specific measure exists rather than implying one does.

What it is

5:3 FTCA is a polyfluorinated carboxylic acid — a molecule with a fluorinated block and a small hydrogenated tail. The name encodes the structure: five fully fluorinated carbons (a C₅F₁₁– perfluoropentyl group) joined to three hydrogenated carbons that finish in a carboxylic acid group (–CH₂CH₂COOH). Because it still holds carbon–hydrogen bonds, it is not a fully perfluorinated PFAA like PFOA; it is a fluorotelomer degradation product that sits partway between the parent finish and the terminal perfluorinated acids.

It does not start out as 5:3 FTCA. It is what remains after 6:2 fluorotelomer alcohol (6:2 FTOH) — the reactive building block of many stain- and grease-resistant finishes — is metabolized by microbes and organisms. Most of that biotransformation stalls at 5:3 FTCA: the molecule is partly processed, but the perfluorinated backbone is not defluorinated, so it persists. That combination of a specific parent chemistry and a stubborn, non-fluoride-releasing end state is what makes 5:3 FTCA useful as a source marker.

Where you encounter it

Not the bedroom air — the product lifecycle

The honest starting point: there is no evidence that 5:3 FTCA off-gasses from a mattress or furnishing into bedroom air. It is neither volatile nor an inhalation hazard in the sleeping space. The link to your bedroom runs through the lifecycle of treated goods. The 6:2 fluorotelomer finishes that make carpets, upholstery textiles, and some historical covers stain- and water-resistant are the exact parent chemistry that degrades to 5:3 FTCA — but that degradation happens after disposal, not while the product sits in your home.

Landfill leachate — where it dominates

When treated textiles, carpets, and grease-proof packaging reach the end of their life, they go to landfill. Inside the landfill, the fluorotelomer finishes biodegrade, and 5:3 FTCA accumulates as the persistent intermediate. In leachate surveys it is repeatedly the single most abundant PFAS present. That leachate then migrates — collected leachate is commonly sent to wastewater treatment plants, and uncontrolled leachate can reach groundwater. This is why 5:3 FTCA is best understood as the "water-side receipt" for the treated-textile economy: the exposure pathway for the compound itself is drinking water, downgradient of waste.

The diagnostic value

The dominance of 5:3 FTCA is source-specific. It is characteristic of the consumer-waste stream, and it is not a signature of the other big PFAS sources: aqueous film-forming firefighting foam leaves behind PFHxS, PFOS, and 6:2 FTS; fluoropolymer manufacturing leaves PFOA and GenX. When 5:3 FTCA tops a water sample, that pattern points to landfill and consumer-goods origin. Choosing untreated, uncoated bedding and furnishings reduces the upstream feedstock that eventually degrades to it — but the exposure route for the molecule itself remains water, not the bedside.

What the research says

Dominant in US landfill leachate — Lang 2017

Lang, Allred, Field, Levis and Barlaz (2017) in Environmental Science & Technology ran a national survey of US municipal landfill leachate — 95 samples analyzed for 70 PFAS — and found 5:3 FTCA dominant across most of them. Peer-reviewed The study estimated a national mass release of measured PFAS from US landfill leachate to wastewater treatment plants on the order of 563–638 kg for 2013, with higher releases from younger waste. It established 5:3 FTCA as the defining PFAS of the municipal-waste stream at national scale.

Dominance plus source attribution — Capozzi 2023

Capozzi and colleagues (2023) in Chemosphere sampled 17 Washington State landfills for 32 PFAS plus a total-oxidizable-precursor (TOP) assay and again found 5:3 FTCA the dominant PFAS. Peer-reviewed Total PFAS ranged from 61 to 172,976 ng/L before oxidation. Their positive-matrix-factorization source apportionment resolved a dominant factor driven by 5:3 FTCA and identified carpets, textiles, and food packaging as the main sources — the compound-specific link from consumer goods to the water-side marker.

Why it resists breakdown — Wu 2024

Wu, Goodrow, Chen and Li (2024) in Water Research studied activated sludge from four New York-metro wastewater treatment plants. Peer-reviewed The 6:2 FTCA sibling released substantial fluoride (0.56–1.83 fluoride ions per molecule), but 5:3 FTCA released almost none (0.01–0.09) even though 25–68% of it was biologically removed. The mechanism is the key finding: 5:3 FTCA transforms through non-fluoride-releasing pathways (such as CoA adducts and conjugates), so the fluorinated backbone survives biological treatment and the molecule accumulates as a terminal marker rather than being destroyed.

Biopersistence — Kabadi 2020

Kabadi and colleagues (2020) in Toxicology and Applied Pharmacology used pharmacokinetic modeling of a 90-day 6:2 FTOH rat study and found that among the metabolites, 5:3 FTCA had the highest internal exposure and the slowest clearance. Peer-reviewed The estimated elimination half-lives were on the order of one year in plasma, liver, and fat — a biopersistence profile that helps explain why 5:3 FTCA is the metabolite that accumulates.

What helps reduce exposure

Reduce the upstream feedstock. Choosing textiles, carpets, bedding, and food packaging without fluorinated stain- and grease-resistant finishes shrinks the pool of 6:2 telomer chemistry that eventually degrades to 5:3 FTCA. Inferred from the source attribution in Lang 2017 and Capozzi 2023; a lifecycle rather than a personal-exposure intervention

Treat the water, not the air. Because the exposure route is drinking water, the relevant interventions are water-side: granular activated carbon, ion exchange, and reverse osmosis are the technologies used for PFAS broadly. Inferred from general PFAS water-treatment performance; no 5:3-FTCA-specific removal-efficacy study was identified, so treat efficacy figures as general PFAS estimates, not compound-specific

What does NOT help

• Standard biological wastewater treatment. Activated sludge removes some 5:3 FTCA but liberates negligible fluoride — the fluorinated backbone survives (Wu 2024). Conventional treatment relocates and transforms the molecule; it does not destroy it. Peer-reviewed
• Reading a TOP assay or a targeted PFAS panel as the whole picture. Chain-shortening and net mass loss during oxidation can make a landfill look like it is "improving" on a targeted sum even when the true organofluorine burden is unchanged. Targeted panels that omit 5:3 FTCA understate it. Inferred from the oxidation and mass-balance findings in Capozzi 2023 and Wu 2024
• Air purifiers and bedroom source-control. There is no inhalation pathway for 5:3 FTCA, so HEPA and carbon air cleaning do nothing for it. This is a water contaminant, and bedroom air interventions are aimed at the wrong medium. Inferred — no volatilization pathway is documented for this compound

Open research questions

• The toxicology is sparse. There is no IARC or EPA individual hazard classification, few mammalian endpoints for the acid itself, and most human-relevant inference comes from the 6:2 FTOH parent plus the roughly one-year biopersistence estimate. Speculation on human health effects; the compound-specific dataset is thin
• The fate of the non-fluoride-releasing transformation products (CoA adducts and conjugates) is unresolved — whether they are benign or a hidden organofluorine reservoir. Speculation
• How much 5:3 FTCA ultimately converts to short-chain terminal PFCAs versus persists indefinitely is not well quantified. Speculation
• Human body-burden data are limited, and drinking-water treatment efficacy for 5:3 FTCA specifically has not been characterized — removal figures are extrapolated from general PFAS performance. Inferred from the absence of compound-specific treatment studies

Citations

1. Lang JR, Allred BM, Field JA, Levis JW, Barlaz MA (2017). National estimate of per- and polyfluoroalkyl substance (PFAS) release to US municipal landfill leachate. Environmental Science & Technology, 51(4):2197-2205. DOI 10.1021/acs.est.6b05005 Peer-reviewed — national landfill-leachate survey; 5:3 FTCA dominant
2. Capozzi SL, Leang AL, Rodenburg LA, Chandramouli B, Delistraty DA, Carter CH (2023). PFAS in municipal landfill leachate: occurrence, transformation, and source apportionment. Chemosphere, 334:138924. DOI 10.1016/j.chemosphere.2023.138924 Peer-reviewed — 5:3 FTCA dominant; carpets, textiles, packaging as sources
3. Wu C, Goodrow S, Chen H, Li M (2024). Defluorination and biotransformation of fluorotelomer carboxylic acids by activated sludge. Water Research, 254:121431. DOI 10.1016/j.watres.2024.121431 Peer-reviewed — 5:3 FTCA resists defluorination
4. Kabadi SV, Fisher JW, Doerge DR, Mehta D, Aungst J, Rice P (2020). Characterizing biopersistence potential of the metabolite 5:3 fluorotelomer carboxylic acid after repeated oral exposure to the 6:2 fluorotelomer alcohol. Toxicology and Applied Pharmacology, 388:114878. DOI 10.1016/j.taap.2020.114878 Peer-reviewed — approximately one-year elimination half-life
5. Biomonitoring California (California Department of Public Health / OEHHA). 5:3 fluorotelomer carboxylic acid — Designated and Priority Chemical for biomonitoring (an exposure-monitoring designation, not a hazard classification). biomonitoring.ca.gov Regulatory
6. US National Library of Medicine, PubChem. 5:3 Fluorotelomer carboxylic acid, CID 14632790; CAS 914637-49-3; formula C₈H₅F₁₁O₂; MW 342.11. pubchem.ncbi.nlm.nih.gov Spec — identity and physical constants

Frequently asked questions

• Is 5:3 FTCA in my mattress or bedroom air?

  There is no evidence that 5:3 FTCA is a bedroom off-gas. It is not volatile and does not evaporate from a mattress into the air you breathe. It forms later in the product lifecycle: when the 6:2 fluorotelomer stain- and water-resistant finishes on textiles, carpets, and grease-proof packaging break down after those goods are thrown away, 5:3 FTCA is the persistent intermediate that results. It then shows up in landfill leachate and in water — not in bedroom air. The connection to your bedroom is the product lifecycle of treated goods, not inhalation.

• Why is 5:3 FTCA called a marker or fingerprint chemical?

  Its dominance points to a single source. 5:3 FTCA is the stable end-point of 6:2 fluorotelomer chemistry — the finishes used on carpets, textiles, and food packaging. When it is the most abundant PFAS in a water sample, that pattern signals a consumer-waste and landfill origin, as opposed to firefighting foam (which leaves PFHxS, PFOS, and 6:2 FTS) or fluoropolymer manufacturing (which leaves PFOA and GenX). Lang and colleagues (2017) and Capozzi and colleagues (2023) both found 5:3 FTCA dominant in landfill leachate, and Capozzi's source-apportionment modeling tied it specifically to carpets, textiles, and packaging.

• Is 5:3 FTCA regulated or classified as harmful?

  No individual compound-specific hazard classification exists. It has not been evaluated by IARC, it is not on the California Proposition 65 list, and it is not one of the six PFAS given an individual drinking-water limit in the US EPA's 2024 rule (which covers PFOA, PFOS, PFHxS, PFNA, GenX/HFPO-DA, and PFBS). Its regulatory relevance is twofold: it is captured under class-wide PFAS frameworks, and it is a Designated and Priority Chemical for Biomonitoring California — which is a monitoring designation, not a hazard label. The underlying toxicology is sparse.

• Does 5:3 FTCA break down in the environment?

  Poorly. In activated sludge, Wu and colleagues (2024) found that 25–68% of 5:3 FTCA was biologically removed, yet it released almost no fluoride (roughly 0.01–0.09 fluoride ions per molecule) — meaning the fluorinated backbone survives and the molecule transforms through non-fluoride-releasing pathways rather than being destroyed. In a rat model, Kabadi and colleagues (2020) estimated elimination half-lives of around one year. It behaves as a persistent dead-end product: partly processed, but not broken down.

Related compounds

• PFOA — the C8 perfluoroalkyl carboxylate that is the fingerprint of fluoropolymer manufacturing, not the consumer-waste stream where 5:3 FTCA dominates
• PFOS — C8 perfluoroalkyl sulfonate; a firefighting-foam and legacy marker, contrasting with 5:3 FTCA's landfill signature
• 6:2 FTS — 6:2 fluorotelomer sulfonate; a sibling fluorotelomer degradation product from the same 6:2 telomer chemistry, more associated with firefighting foam
• PFHxS — C6 perfluoroalkyl sulfonate; another firefighting-foam marker that contrasts with the consumer-goods origin of 5:3 FTCA

Embr is a sleep environment company researching the chemistry of the bedroom. See the methodology page for how this Atlas tags claims by evidence strength. For broader context on PFAS exposure pathways, see non-toxic bedroom and PFAS in 2026.

Last reviewed 2026-07-14. If you find a factual error, contact us.