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PFUnA

Perfluoroundecanoic acid

2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-henicosafluoroundecanoic acid

Also known as PFUnAPFUnDA
Perfluoroundecanoic acidHenicosafluoroundecanoic acid2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-henicosafluoroundecanoic acidPerfluoro-n-undecanoic acidPFUnDAJPZ6FNL628C11-PFAPFUA compound

An 11-carbon long-chain PFCA between PFDA (10C) and PFDoA (12C). No PFUnA-specific RfD; 0.006 ppt benchmark from EPA's 2024 IRIS PFDA value. Detected at 172 utilities serving 4.3M people across 17 states; NJ-dominated occurrence.

Group
PFAS
Regulatory status
UCMR
Unregulated Contaminant Monitoring Rule
Top removal tech
Activated carbon

Primary concern: Immune and developmental effects (PFDA-surrogate)

Affected organ systems

Liver Immune Developmental Endocrine Affecting the body's hormone system — thyroid, adrenal, reproductive, or metabolic hormones.

Health effects

Carcinogen A substance known or reasonably suspected to cause cancer based on human or animal studies. Immunotoxin Suppresses or alters the immune system. Can increase risk of infection or reduce vaccine effectiveness. Endocrine disruptor Mimics or blocks the body's hormones (estrogen, thyroid, testosterone). Can affect development, reproduction, and metabolism at very low doses. Developmental toxin Causes harm during development before birth or in early childhood — birth defects, low birth weight, delayed growth, or learning problems later in life. Hepatotoxin Damages the liver. Effects range from elevated liver enzymes on a blood test to fatty liver disease and, with prolonged exposure, liver cancer.

Exposure routes

Drinking water Dietary Occupational In utero Breast milk

Vulnerable populations

Pregnant Infants Children

Overview

Perfluoroundecanoic acid (PFUnA, also abbreviated PFUnDA) is an 11-carbon perfluoroalkyl carboxylic acid (C11HF21O2, MW 564) — between PFDA (10C) and PFDoA (12C) on the long-chain PFCA spectrum. The long perfluorinated chain gives PFUnA low water solubility, strong serum-protein binding, and a multi-year human serum elimination half-life on par with PFDA (~3-5 years). PFUnA has been detected at 172 U.S. public water systems serving roughly 4.3 million people across 17 states; New Jersey dominates the occurrence list (45 utilities, 2.5M served), followed by North Carolina (32 utilities) and New York (35 utilities).

Pollution sources

Industry Manufacturing Military AFFF Aqueous Film-Forming Foam — firefighting foam used at military bases and airports for fuel fires. The leading source of PFAS contamination in groundwater near former training sites. Consumer products

Sources

PFUnA sources span the same pathways as other long-chain PFCAs: (1) industrial discharge from fluoropolymer manufacturing — the New Jersey dominance traces to the same Solvay Specialty Polymers West Deptford / Paulsboro plume that drives PFNA, and the North Carolina cluster (Holly Springs, Harnett County, Lillington systems, Linden, Coats, Angier, Pittsboro, Chapel Ridge S/d all at 2.10 ppt) reflects the Chemours Fayetteville Works fingerprint on the Cape Fear basin; (2) AFFF firefighting-foam release at military installations — Bragg Communities/NTA at Fort Liberty, NC (formerly Fort Bragg, 2.10 ppt) is a direct on-base detection; (3) localized industrial point sources — Lincoln, AL (13.3 ppt), the St. Clair County, AL cluster (Odenville, Pell City, Springville at 7.58 ppt) and the Lehigh Valley Emmaus, PA system (21.1 ppt over 23 tests, highest measured U.S. average) reflect regional industrial impact; (4) the Lowcountry South Carolina Moncks Corner / Summerville cluster (Summerville at 7.10 ppt serving 81,750 people, plus four co-located BCWSA systems) reflects shared source-water blend in the regional Cooper River basin.

Health risks

There is no PFUnA-specific EPA Reference Dose or IRIS toxicological review. The 0.006 ppt drinking-water benchmark is derived by applying EPA's 2024 IRIS PFDA toxicity value as a surrogate, on the basis of structural similarity (PFUnA is one -CF2- longer than PFDA) and shared toxicological endpoints across long-chain PFCAs: hepatotoxicity, immune suppression, thyroid disruption, and developmental effects. PFUnA has not been classified as a carcinogen by IARC or NTP. Human pharmacokinetic data is limited; serum half-life is expected to be multi-year, on par with PFDA. PFUnA is not included in the 2024 NPDWR Hazard Index mixture and has no individual federal MCL.

Effective treatments

Activated carbon Granular or block carbon that traps organic contaminants as water flows through. The most common point-of-use filter media — handles chlorine taste, VOCs, pesticides, and many PFAS. Reverse osmosis A semipermeable membrane that pushes water through under pressure, leaving most dissolved contaminants behind. Removes a very broad range — PFAS, lead, arsenic, nitrate, salts — at the cost of slower flow and some wastewater. Ion exchange Resin beads that swap unwanted ions (lead, calcium, certain PFAS, perchlorate) for harmless ones like sodium. Common in water softeners and PFAS treatment columns.

Does not remove

UV Ultraviolet light that disrupts the DNA of bacteria, viruses, and protozoa as water flows past the lamp. Disinfects but doesn't remove chemicals or particles. Chlorination Adds chlorine or hypochlorite to kill bacteria and viruses. The most common disinfection method in US water systems; leaves a residual that keeps water protected through the distribution pipes. Boil Kills bacteria, viruses, and protozoa after a one-minute rolling boil. Does NOT remove chemicals like lead, nitrate, or PFAS — boiling actually concentrates them as water evaporates.

NSF certifications

NSF/ANSI 53 Health-related contaminants NSF/ANSI 58 Reverse osmosis systems

Water treatment

PFUnA is one of the easier UCMR 5 PFAS to remove with granular activated carbon: long-chain PFCAs adsorb strongly onto GAC and break through later than short-chain PFCAs at comparable loading rates. Anion exchange resin and high-pressure membranes (reverse osmosis, nanofiltration) are also highly effective. Conventional treatment processes — coagulation, sand filtration, disinfection, UV, and ozonation — do not remove PFUnA. Boiling concentrates rather than removes it. NSF/ANSI 53 and NSF P473 certify point-of-use filters for general PFAS reduction; NSF/ANSI 58 covers RO systems. As with PFDA, PFDoA, PFTrDA, and PFTA, the 0.006 ppt PFDA-surrogate guideline sits below analytical reporting limits and is not operationally verifiable — utilities meeting the long-chain PFAS NPDWR MCLs (PFOA, PFOS, PFNA, PFHxS, HFPO-DA) with GAC, AIX, or RO will incidentally control PFUnA at the same time.

Gallery

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Related contaminants

Perfluorodecanoic acid (PFDA) A 10-carbon long-chain perfluorocarboxylic acid (PFCA) with high environmental persistence and human bioaccumulation. 2024 EPA IRIS RfD for immune/developmental effects yields the strictest UCMR 5 health benchmark. Perfluorododecanoic acid (PFDoA) A 12-carbon long-chain perfluorocarboxylic acid, more bioaccumulative than PFDA. Risk-assessed by surrogate to PFDA's 2024 IRIS RfD; detected in 93 U.S. public water systems serving 2.1M people under UCMR 5. Perfluorotridecanoic acid (PFTrDA) A 13-carbon long-chain PFCA between PFDoA (12C) and PFTA (14C). No PFTrDA-specific RfD; 0.006 ppt benchmark derived from EPA's 2024 IRIS PFDA value. Detected at 41 utilities serving 371K people across 8 states.

Chemistry + classification data sourced from public databases (PubChem, EPA CompTox, IARC monographs); 3D molecular models from 3d.nih.gov where available.