getwater.tech getwater .tech
Open app
← Back to Contaminants
Placeholder hero image (16:9)

PFPeS

Perfluoropentane sulfonic acid

1,1,2,2,3,3,4,4,5,5,5-undecafluoropentane-1-sulfonic acid

Also known as PFPeS
perfluoropentanesulfonic acid1-Pentanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,5-undecafluoro-1,1,2,2,3,3,4,4,5,5,5-undecafluoropentane-1-sulfonic acidPerfluoropentane-1-sulfonic acidYWK28LB8TL1,1,2,2,3,3,4,4,5,5,5-Undecafluoro-1-pentanesulfonic acidundecafluoro-1-pentanesulfonic AcidPFPeS perfluoropentanesulfonic acid

A 5-carbon short-chain perfluoroalkyl sulfonic acid, between PFBS (4C) and PFHxS (6C). No PFPeS-specific EPA RfD; risk class-extrapolated from PFAS. Detected at 299 utilities serving 9.4M people across 28 states.

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

Primary concern: Class-extrapolated PFAS effects (no PFPeS-specific RfD)

Affected organ systems

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

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

Vulnerable populations

Pregnant Infants Children

Overview

Perfluoropentanesulfonic acid (PFPeS) is a 5-carbon perfluoroalkyl sulfonic acid (C5HF11O3S, MW 350) — between PFBS (4 carbons) and PFHxS (6 carbons) on the PFSA chain-length spectrum. OECD classifies PFSAs with fewer than 6 carbons as short-chain, placing PFPeS alongside PFBS rather than with the NPDWR-regulated long-chain PFSAs (PFHxS, PFHpS, PFOS). PFPeS has been detected at 299 U.S. public water systems serving roughly 9.4 million people across 28 states. There is no PFPeS-specific EPA IRIS Reference Dose and no individual federal MCL; PFPeS is also not included in the 2024 NPDWR Hazard Index mixture (which covers PFHxS, PFNA, HFPO-DA, and PFBS).

Pollution sources

Industry 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. Manufacturing Consumer products

Sources

PFPeS contamination carries a strong AFFF firefighting-foam fingerprint, consistent with other long- and medium-chain PFSAs: Camp Pendleton (North), CA at 6.45 ppt over 36 tests is a direct on-base detection; Ladd Center, RI (22.8 ppt) and Exeter Job Corps Center, RI (21.9 ppt over 15 tests) trace to the former Navy Construction Battalion Center Davisville footprint; Fort Riley, KS (4.30 ppt) is another on-base detection. Industrial and 3M-era sources also appear: the Ann Arbor, MI city system (7.37 ppt, serving 118,017 people) sits within the regional fluorochemical-industry corridor, and Cottage Grove, MN (5.45 ppt over 31 tests) and Oakdale, MN (3.01 ppt) reflect the 3M Cottage Grove groundwater plume. PFPeS arises both as a primary industrial / AFFF release and as a biotransformation product of longer perfluorooctanesulfonyl-precursor chemistries (Scotchgard-era surfactants).

Health risks

There is no PFPeS-specific Reference Dose, Health Reference Level, or carcinogen classification from EPA, IARC, or NTP. Risk assessment is class-extrapolated from the better-studied perfluoroalkyl sulfonic acids: PFOS, PFHxS, and PFBS share the dose-defining endpoints reported in EPA's 2024 NPDWR and 2023 IRIS reviews — hepatotoxicity, immune suppression (reduced antibody response to childhood vaccines), thyroid hormone disruption, and developmental effects. PFPeS has not been formally classified as a carcinogen by IARC or NTP. Human pharmacokinetic data for PFPeS is sparse; expected behavior interpolates between PFBS (median serum half-life ~26 days) and PFHxS (~8.5 years), with PFPeS likely sitting closer to PFHxS than to PFBS on a chain-length basis, but no defensible single half-life value is published.

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.

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

PFPeS responds to the standard long-chain PFAS treatment train more effectively than the short-chain PFCAs: the sulfonate head group provides electrostatic affinity for anion exchange resin, and the 5-carbon perfluorinated tail provides adequate hydrophobic adsorption onto granular activated carbon (GAC). GAC breakthrough on PFPeS occurs later than on PFBS (4C) but earlier than on PFHxS (6C) or PFOS (8C). High-pressure membranes (reverse osmosis, nanofiltration) are also highly effective. Conventional treatment processes — coagulation, sand filtration, disinfection, UV, and ozonation — do not remove PFPeS. 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. Utilities meeting the federal PFOS / PFHxS NPDWR MCLs with GAC, AIX, or RO will incidentally control PFPeS at the same time.

Gallery

Placeholder gallery 1 (1:1)Placeholder gallery 2 (1:1)

Related contaminants

Perfluorobutane sulfonate (PFBS) A short-chain perfluoroalkyl sulfonic acid (PFSA) — among the most-detected PFAS in U.S. drinking water (4,285 utilities, 99M served). 3M's chosen PFOS-replacement chemistry post-2002; regulated as part of the NPDWR Hazard Index mixture. Perfluorohexane sulfonate (PFHXS) A 6-carbon long-chain PFSA with 2024 NPDWR individual MCL of 10 ppt. EPA's 2023 IRIS RfD targets developmental immune effects; detected at 3,144 utilities serving 71M people across 46 states. Perfluoroheptane sulfonic acid (PFHpS) A 7-carbon long-chain perfluoroalkyl sulfonic acid, one shorter than PFOS. Risk-assessed by surrogate to EPA's 2024 PFHxS IRIS toxicity value; detected at 70 utilities serving 1.3M people.

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